fix coding style

For indexed PNGs, we only need to allocate a palette large enough to accommodate the number of indexed colours in the image. For images that don't use all 256 colours, this slightly reduces the memory usage for these images.

.github/ISSUE_TEMPLATE/config.yml

@@ -10,5 +10,5 @@ contact_links:
     url: https://discord.openra.net/
     about: Join the community Discord server for community discussion and support.
   - name: OpenRA IRC Channel
-    url: https://webchat.freenode.net/#openra
-    about: Join our development IRC channel on freenode for discussion of development topics.
+    url: https://web.libera.chat/#openra
+    about: Join our development IRC channel on Libera for discussion of development topics.

.github/PULL_REQUEST_TEMPLATE.md

@@ -13,4 +13,4 @@ You can help speed up the review process by following a few steps:
 * Respond to review comments as soon as you reasonably can.  Reviewers will usually prioritize Pull Requests that are still fresh in their minds.  Make sure to leave a comment when you push new changes, otherwise GitHub does not automatically notify reviewers!
 * Leave a polite comment asking for reviews if a week or more has passed without feedback.
 
-If you need any help you can ask in the #openra IRC channel on freenode (most active during European evenings).
+If you need any help you can ask on Discord (https://discord.openra.net) or in the #openra IRC channel on Libera (not as active as Discord).

.github/workflows/ci.yaml

@@ -1,48 +0,0 @@
-name: Continuous Integration
-
-on:
-  push:
-  pull_request:
-    branches: [ bleed ]
-
-jobs:
-  linux-mono:
-    name: Linux (mono)
-    runs-on: ubuntu-20.04
-
-    steps:
-      - name: Clone Repository
-        uses: actions/checkout@v2
-
-      - name: Check Code
-        run: |
-          mono --version
-          make check
-          mono ~/.nuget/packages/nunit.consolerunner/3.11.1/tools/nunit3-console.exe --noresult bin/OpenRA.Test.dll
-
-      - name: Check Mods
-        run: |
-          sudo apt-get install lua5.1
-          make check-scripts
-          make test
-
-  windows:
-    name: Windows (Framework 4.7)
-    runs-on: windows-2019
-
-    steps:
-      - name: Clone Repository
-        uses: actions/checkout@v2
-
-      - name: Check Code
-        shell: powershell
-        run: |
-          .\make.ps1 check
-          Invoke-Expression "$home\.nuget\packages\nunit.consolerunner\3.11.1\tools\nunit3-console.exe --noresult bin/OpenRA.Test.dll"
-
-      - name: Check Mods
-        run: |
-          chocolatey install lua --version 5.1.5.52
-          $ENV:Path = $ENV:Path + ";C:\Program Files (x86)\Lua\5.1\"
-          .\make.ps1 check-scripts
-          .\make.ps1 test

.github/workflows/ci.yml

@@ -0,0 +1,81 @@
+name: Continuous Integration
+
+on:
+  push:
+  pull_request:
+    branches: [ bleed, 'prep-*' ]
+
+permissions:
+  contents: read  #  to fetch code (actions/checkout)
+
+jobs:
+  linux:
+    name: Linux (.NET 6.0)
+    runs-on: ubuntu-22.04
+
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v4
+
+      - name: Install .NET 6.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
+
+      - name: Check Code
+        run: |
+          make check
+          make tests
+
+      - name: Check Mods
+        run: |
+          sudo apt-get install lua5.1
+          make check-scripts
+          make TREAT_WARNINGS_AS_ERRORS=true test
+
+  linux-mono:
+    name: Linux (mono)
+    runs-on: ubuntu-22.04
+
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v4
+
+      - name: Check Code
+        run: |
+          mono --version
+          make RUNTIME=mono check
+
+      - name: Check Mods
+        run: |
+          # check-scripts does not depend on .net/mono, so is not needed here
+          make RUNTIME=mono TREAT_WARNINGS_AS_ERRORS=true test
+
+  windows:
+    name: Windows (.NET 6.0)
+    runs-on: windows-2019
+
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v4
+
+      - name: Install .NET 6.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
+
+      - name: Check Code
+        shell: powershell
+        run: |
+          # Work around runtime failures on the GH Actions runner
+          dotnet nuget add source https://api.nuget.org/v3/index.json -n nuget.org
+          .\make.ps1 check
+          .\make.ps1 tests
+
+      - name: Check Mods
+        run: |
+          choco install lua --version 5.1.5.52
+          $ENV:Path = $ENV:Path + ";C:\Program Files (x86)\Lua\5.1\"
+          $ENV:TREAT_WARNINGS_AS_ERRORS = "true"
+          .\make.ps1 check-scripts
+          .\make.ps1 test

.github/workflows/documentation.yml

@@ -1,6 +1,9 @@
 name: Deploy Documentation
 
 on:
+  push:
+    branches: [ bleed ]
+    tags: [ 'release-*', 'playtest-*' ]
   workflow_dispatch:
     inputs:
       tag:
@@ -8,92 +11,140 @@ on:
         required: true
         default: 'release-xxxxxxxx'
 
+permissions:
+  contents: read  #  to fetch code (actions/checkout)
+
 jobs:
+  prepare:
+    name: Prepare version strings
+    if: github.repository == 'openra/openra'
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Prepare environment variables
+        run: |
+          if [ "${{ github.event_name }}" = "push" ]; then
+            if [ "${{ github.ref_type }}" = "tag" ]; then
+              VERSION_TYPE=`echo "${GITHUB_REF#refs/tags/}" | cut -d"-" -f1`
+              echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> $GITHUB_ENV
+              echo "VERSION_TYPE=$VERSION_TYPE" >> $GITHUB_ENV
+            else
+              echo "GIT_TAG=bleed" >> $GITHUB_ENV
+              echo "VERSION_TYPE=bleed" >> $GITHUB_ENV
+            fi
+          else
+            VERSION_TYPE=`echo "${{ github.event.inputs.tag }}" | cut -d"-" -f1`
+            echo "GIT_TAG=${{ github.event.inputs.tag }}" >> $GITHUB_ENV
+            echo "VERSION_TYPE=$VERSION_TYPE" >> $GITHUB_ENV
+          fi
+    outputs:
+      git_tag: ${{ env.GIT_TAG }}
+      version_type: ${{ env.VERSION_TYPE }}
+
   wiki:
     name: Update Wiki
-    if: github.repository == 'openra/openra'
-    runs-on: ubuntu-20.04
+    needs: prepare
+    if: github.repository == 'openra/openra' && needs.prepare.outputs.version_type != 'bleed'
+    runs-on: ubuntu-22.04
     steps:
+      - name: Debug output
+        run: |
+          echo ${{ needs.prepare.outputs.git_tag }}
+          echo ${{ needs.prepare.outputs.version_type }}
+
       - name: Clone Repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
-          ref: ${{ github.event.inputs.tag }}
+          ref: ${{ needs.prepare.outputs.git_tag }}
+
+      - name: Install .NET 6
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
 
       - name: Prepare Environment
         run: |
           make all
 
       - name: Clone Wiki
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           repository: openra/openra.wiki
           token: ${{ secrets.DOCS_TOKEN }}
           path: wiki
 
       - name: Update Wiki (Playtest)
-        if: startsWith(github.event.inputs.tag, 'playtest-')
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
+        if: startsWith(needs.prepare.outputs.git_tag, 'playtest-')
         run: |
-          ./utility.sh all --settings-docs "${GIT_TAG}" > "wiki/Settings (playtest).md"
+          ./utility.sh all --settings-docs "${{ needs.prepare.outputs.git_tag }}" > "wiki/Settings (playtest).md"
 
       - name: Update Wiki (Release)
-        if: startsWith(github.event.inputs.tag, 'release-')
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
+        if: startsWith(needs.prepare.outputs.git_tag, 'release-')
         run: |
-          ./utility.sh all --settings-docs "${GIT_TAG}" > "wiki/Settings.md"
+          ./utility.sh all --settings-docs "${{ needs.prepare.outputs.git_tag }}" > "wiki/Settings.md"
 
       - name: Push Wiki
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
         run: |
           cd wiki
           git config --local user.email "actions@github.com"
           git config --local user.name "GitHub Actions"
-          git add --all
-          git commit -m "Update auto-generated documentation for ${GIT_TAG}"
-          git push origin master
+          git status
+          git diff-index --quiet HEAD || \
+          (
+            git add --all && \
+            git commit -m "Update auto-generated documentation for ${{ needs.prepare.outputs.git_tag }}" && \
+            git push origin master
+          )
 
   docs:
     name: Update docs.openra.net
+    needs: prepare
     if: github.repository == 'openra/openra'
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
-      - name: Clone docs.openra.net
-        uses: actions/checkout@v2
+      - name: Debug output
+        run: |
+          echo ${{ needs.prepare.outputs.git_tag }}
+          echo ${{ needs.prepare.outputs.version_type }}
+
+      - name: Clone Repository
+        uses: actions/checkout@v4
         with:
-          repository: openra/docs.git
+          ref: ${{ needs.prepare.outputs.git_tag }}
+
+      - name: Install .NET 6
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
+
+      - name: Prepare Environment
+        run: |
+          make all
+
+      # version_type is release/playtest/bleed - the name of the target branch.
+      - name: Clone docs.openra.net
+        uses: actions/checkout@v4
+        with:
+          repository: openra/docs
           token: ${{ secrets.DOCS_TOKEN }}
           path: docs
-          ref: ${{ github.event.inputs.tag }}
+          ref: ${{ needs.prepare.outputs.version_type }}
 
-      - name: Update docs.openra.net (Playtest)
-        if: startsWith(github.event.inputs.tag, 'playtest-')
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
+      - name: Generate docs files
         run: |
-          ./utility.sh all --docs "${GIT_TAG}" > "docs/playtest/traits.md"
-          ./utility.sh all --weapon-docs "${GIT_TAG}" > "docs/playtest/weapons.md"
-          ./utility.sh all --lua-docs "${GIT_TAG}" > "docs/playtest/lua.md"
+          ./utility.sh all --docs "${{ needs.prepare.outputs.git_tag }}" | python3 ./packaging/format-docs.py > "docs/api/traits.md"
+          ./utility.sh all --weapon-docs "${{ needs.prepare.outputs.git_tag }}" | python3 ./packaging/format-docs.py > "docs/api/weapons.md"
+          ./utility.sh all --sprite-sequence-docs "${{ needs.prepare.outputs.git_tag }}" | python3 ./packaging/format-docs.py > "docs/api/sprite-sequences.md"
+          ./utility.sh all --lua-docs "${{ needs.prepare.outputs.git_tag }}" > "docs/api/lua.md"
 
-      - name: Update docs.openra.net (Release)
-        if: startsWith(github.event.inputs.tag, 'release-')
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
-        run: |
-          ./utility.sh all --docs "${GIT_TAG}" > "docs/release/traits.md"
-          ./utility.sh all --weapon-docs "${GIT_TAG}" > "docs/release/weapons.md"
-          ./utility.sh all --lua-docs "${GIT_TAG}" > "docs/release/lua.md"
-
-      - name: Push docs.openra.net
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
+      - name: Update docs.openra.net
         run: |
           cd docs
           git config --local user.email "actions@github.com"
           git config --local user.name "GitHub Actions"
-          git add --all
-          git commit -m "Update auto-generated documentation for ${GIT_TAG}"
-          git push origin master
-
+          git status
+          git diff-index --quiet HEAD || \
+          (
+            git add api/*.md && \
+            git commit -m "Update auto-generated documentation for ${{ needs.prepare.outputs.git_tag }}" && \
+            git push origin ${{ needs.prepare.outputs.version_type }}
+          )

.github/workflows/itch.yml

@@ -8,24 +8,23 @@ on:
         required: true
         default: 'release-xxxxxxxx'
 
+permissions: {}
 jobs:
   itch:
     name: Deploy to itch.io
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: github.repository == 'openra/openra'
     steps:
       - name: Download Packages
-        env:
-          GIT_TAG: ${{ github.event.inputs.tag }}
         run: |
-          wget -q "https://github.com/${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-${GIT_TAG}-x64.exe"
-          wget -q "https://github.com/${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-${GIT_TAG}-x64-winportable.zip" -O "OpenRA-${GIT_TAG}-x64-win-itch.zip"
-          wget -q "https://github.com${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-${GIT_TAG}.dmg"
-          wget -q "https://github.com/${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-Dune-2000-x86_64.AppImage"
-          wget -q "https://github.com/${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-Red-Alert-x86_64.AppImage"
-          wget -q "https://github.com/${{ github.repository }}/releases/download/${GIT_TAG}/OpenRA-Tiberian-Dawn-x86_64.AppImage"
-          wget -q "https://raw.githubusercontent.com/${{ github.repository }}/${GIT_TAG}/packaging/.itch.toml"
-          zip -u "OpenRA-${GIT_TAG}-x64-win-itch.zip" .itch.toml
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-${{ github.event.inputs.tag }}-x64.exe"
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-${{ github.event.inputs.tag }}-x64-winportable.zip" -O "OpenRA-${{ github.event.inputs.tag }}-x64-win-itch.zip"
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-${{ github.event.inputs.tag }}.dmg"
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-Dune-2000-x86_64.AppImage"
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-Red-Alert-x86_64.AppImage"
+          wget -q "https://github.com/${{ github.repository }}/releases/download/${{ github.event.inputs.tag }}/OpenRA-Tiberian-Dawn-x86_64.AppImage"
+          wget -q "https://raw.githubusercontent.com/${{ github.repository }}/${{ github.event.inputs.tag }}/packaging/.itch.toml"
+          zip -u "OpenRA-${{ github.event.inputs.tag }}-x64-win-itch.zip" .itch.toml
 
       - name: Publish Windows Installer
         uses: josephbmanley/butler-publish-itchio-action@master
@@ -33,9 +32,9 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: win
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
-          PACKAGE: OpenRA-${{ github.event.inputs.tag }}}-x64.exe"
+          PACKAGE: OpenRA-${{ github.event.inputs.tag }}-x64.exe
 
       - name: Publish Windows Itch Bundle
         uses: josephbmanley/butler-publish-itchio-action@master
@@ -43,7 +42,7 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: itch
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
           PACKAGE: OpenRA-${{ github.event.inputs.tag }}-x64-win-itch.zip
 
@@ -53,9 +52,9 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: macos
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
-          PACKAGE: OpenRA-${{ github.event.inputs.tag }}}.dmg"
+          PACKAGE: OpenRA-${{ github.event.inputs.tag }}.dmg
 
       - name: Publish RA AppImage
         uses: josephbmanley/butler-publish-itchio-action@master
@@ -63,7 +62,7 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: linux-ra
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
           PACKAGE: OpenRA-Red-Alert-x86_64.AppImage
 
@@ -73,7 +72,7 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: linux-cnc
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
           PACKAGE: OpenRA-Tiberian-Dawn-x86_64.AppImage
 
@@ -83,6 +82,6 @@ jobs:
           BUTLER_CREDENTIALS: ${{ secrets.BUTLER_CREDENTIALS }}
           CHANNEL: linux-d2k
           ITCH_GAME: openra
-          ITCH_USER: openra-developers
+          ITCH_USER: openra
           VERSION: ${{ github.event.inputs.tag }}
           PACKAGE: OpenRA-Dune-2000-x86_64.AppImage

.github/workflows/packaging.yml

@@ -7,13 +7,45 @@ on:
     - 'playtest-*'
     - 'devtest-*'
 
+permissions:
+  contents: write  #  for release creation (svenstaro/upload-release-action)
+
 jobs:
-  linux:
-    name: Linux AppImages
-    runs-on: ubuntu-20.04
+  source:
+    name: Source Tarball
+    runs-on: ubuntu-22.04
     steps:
       - name: Clone Repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
+
+      - name: Prepare Environment
+        run: echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> ${GITHUB_ENV}
+
+      - name: Package Source
+        run: |
+          mkdir -p build/source
+          ./packaging/source/buildpackage.sh "${GIT_TAG}" "${PWD}/build/source"
+
+      - name: Upload Packages
+        uses: svenstaro/upload-release-action@v2
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          tag: ${{ github.ref }}
+          overwrite: true
+          file_glob: true
+          file: build/source/*
+
+  linux:
+    name: Linux AppImages
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v4
+
+      - name: Install .NET 6.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
 
       - name: Prepare Environment
         run: echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> ${GITHUB_ENV}
@@ -21,6 +53,7 @@ jobs:
       - name: Package AppImages
         run: |
           mkdir -p build/linux
+          sudo apt install libfuse2
           ./packaging/linux/buildpackage.sh "${GIT_TAG}" "${PWD}/build/linux"
 
       - name: Upload Packages
@@ -33,16 +66,21 @@ jobs:
           file: build/linux/*
 
   macos:
-    name: macOS Disk Images
-    runs-on: macos-10.15
+    name: macOS Disk Image
+    runs-on: macos-11
     steps:
       - name: Clone Repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
+
+      - name: Install .NET 6.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
 
       - name: Prepare Environment
         run: echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> ${GITHUB_ENV}
 
-      - name: Package Disk Images
+      - name: Package Disk Image
         env:
           MACOS_DEVELOPER_IDENTITY: ${{ secrets.MACOS_DEVELOPER_IDENTITY }}
           MACOS_DEVELOPER_CERTIFICATE_BASE64: ${{ secrets.MACOS_DEVELOPER_CERTIFICATE_BASE64 }}
@@ -53,7 +91,7 @@ jobs:
           mkdir -p build/macos
           ./packaging/macos/buildpackage.sh "${GIT_TAG}" "${PWD}/build/macos"
 
-      - name: Upload Packages
+      - name: Upload Package
         uses: svenstaro/upload-release-action@v2
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
@@ -64,15 +102,21 @@ jobs:
 
   windows:
     name: Windows Installers
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Clone Repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
+
+      - name: Install .NET 6.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '6.0.x'
 
       - name: Prepare Environment
         run: |
           echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> ${GITHUB_ENV}
-          sudo apt install nsis
+          sudo apt-get update
+          sudo apt-get install nsis wine64
 
       - name: Package Installers
         run: |

.gitignore

@@ -13,19 +13,10 @@ obj
 _ReSharper.*/
 /.vs
 
+# Visual Studio Code
+/.vscode/settings.json
+
 # binaries
-mods/*/*.dll
-mods/*/*.mdb
-mods/*/*.pdb
-/*.dll
-/*.dll.config
-/*.so
-/*.dylib
-/*.pdb
-/*.mdb
-/*.exe
-/*.exe.config
-thirdparty/download/*
 IP2LOCATION-LITE-DB1.IPV6.BIN.ZIP
 
 # backup files by various editors
@@ -50,10 +41,6 @@ Settings.md
 openra.6
 update.log
 
-# StyleCop
-*.Cache
-StyleCopViolations.xml
-
 # SublimeText
 *.sublime-project
 *.sublime-workspace

.vscode/extensions.json

@@ -1,7 +1,9 @@
 {
 	"recommendations": [
 		"ms-dotnettools.csharp",
+		"openra.oraide-vscode",
+		"openra.vscode-openra-lua",
 		"EditorConfig.EditorConfig",
-		"ms-vscode.mono-debug"
+		"macabeus.vscode-fluent",
 	]
 }

.vscode/launch.json

@@ -3,62 +3,60 @@
 	"configurations": [
 		{
 			"name": "Launch (TD)",
-			"type": "clr",
-			"linux": {
-				"type": "mono"
-			},
-			"osx": {
-				"type": "mono"
-			},
+			"type": "coreclr",
 			"request": "launch",
-			"program": "${workspaceRoot}/OpenRA.Game.exe",
-			"cwd": "${workspaceRoot}",
-			"args": ["Game.Mod=cnc"],
+			"program": "${workspaceRoot}/bin/OpenRA.dll",
+			"windows": {
+				"program": "${workspaceRoot}/bin/OpenRA.exe",
+			},
+			"args": ["Game.Mod=cnc", "Engine.EngineDir=.."],
 			"preLaunchTask": "build",
 		},
 		{
 			"name": "Launch (RA)",
-			"type": "clr",
-			"linux": {
-				"type": "mono"
-			},
-			"osx": {
-				"type": "mono"
-			},
+			"type": "coreclr",
 			"request": "launch",
-			"program": "${workspaceRoot}/OpenRA.Game.exe",
-			"cwd": "${workspaceRoot}",
-			"args": ["Game.Mod=ra"],
+			"program": "${workspaceRoot}/bin/OpenRA.dll",
+			"windows": {
+				"program": "${workspaceRoot}/bin/OpenRA.exe",
+			},
+			"args": ["Game.Mod=ra", "Engine.EngineDir=.."],
 			"preLaunchTask": "build",
 		},
 		{
 			"name": "Launch (D2k)",
-			"type": "clr",
-			"linux": {
-				"type": "mono"
-			},
-			"osx": {
-				"type": "mono"
-			},
+			"type": "coreclr",
 			"request": "launch",
-			"program": "${workspaceRoot}/OpenRA.Game.exe",
-			"cwd": "${workspaceRoot}",
-			"args": ["Game.Mod=d2k"],
+			"program": "${workspaceRoot}/bin/OpenRA.dll",
+			"windows": {
+				"program": "${workspaceRoot}/bin/OpenRA.exe",
+			},
+			"args": ["Game.Mod=d2k", "Engine.EngineDir=.."],
 			"preLaunchTask": "build",
 		},
 		{
 			"name": "Launch (TS)",
-			"type": "clr",
-			"linux": {
-				"type": "mono"
-			},
-			"osx": {
-				"type": "mono"
-			},
+			"type": "coreclr",
 			"request": "launch",
-			"program": "${workspaceRoot}/OpenRA.Game.exe",
-			"cwd": "${workspaceRoot}",
-			"args": ["Game.Mod=ts"],
+			"program": "${workspaceRoot}/bin/OpenRA.dll",
+			"windows": {
+				"program": "${workspaceRoot}/bin/OpenRA.exe",
+			},
+			"args": ["Game.Mod=ts", "Engine.EngineDir=.."],
+			"preLaunchTask": "build",
+		},
+		{
+			"name": "Launch Utility",
+			"type": "coreclr",
+			"request": "launch",
+			"program": "${workspaceRoot}/bin/OpenRA.Utility.dll",
+			"windows": {
+				"program": "${workspaceRoot}/bin/OpenRA.Utility.exe",
+			},
+			"args": ["all", "--docs", "{DEV_VERSION}"],
+			"env": {
+				"ENGINE_DIR": ".."
+			},
 			"preLaunchTask": "build",
 		},
 	]

.vscode/settings.json

@@ -1,3 +0,0 @@
-{
-	"omnisharp.enableRoslynAnalyzers": true
-}

.vscode/tasks.json

@@ -1,13 +1,36 @@
 {
 	"version": "2.0.0",
+	"options": {
+		"env": {
+			"ENGINE_DIR": ".."
+		}
+	},
 	"tasks": [
 		{
 			"label": "build",
 			"command": "make",
-			"args": ["all"],
+			"args": ["all", "CONFIGURATION=Debug"],
 			"windows": {
 				"command": "make.cmd"
 			}
+		},
+		{
+			"label": "Run Utility",
+			"command": "dotnet ${workspaceRoot}/bin/OpenRA.Utility.dll ${input:modId} ${input:command}",
+			"type": "shell",
 		}
+	],
+	"inputs": [
+		{
+			"id": "modId",
+			"description": "ID of the mod to run",
+			"default": "all",
+			"type": "promptString"
+		}, {
+			"id": "command",
+			"description": "Name of the command + parameters",
+			"default": "",
+			"type": "promptString"
+		},
 	]
 }

AUTHORS

@@ -2,28 +2,30 @@ OpenRA wouldn't be where it is today without the
 hard work of many contributors.
 
 The OpenRA developers are:
-    * Chris Forbes (chrisf)
+    * Gustas Kažukauskas (PunkPun)
     * Lukas Franke (abcdefg30)
-    * Paul Chote (pchote)
-    * Reaperrr
+    * Matthias Mailänder (Mailaender)
 
 Previous developers included:
     * Alli Witheford (alzeih)
     * Caleb Anderson (RobotCaleb)
+    * Chris Forbes (chrisf)
     * Curtis Shmyr (hamb)
     * Daniel Hernandez (Mancano)
     * Igor Popov (ihptru)
-    * Matthias Mailänder (Mailaender)
     * Megan Bowra-Dean (beedee)
     * Mike Bundy (kehaar)
     * Oliver Brakmann (obrakmann)
+    * Paul Chote (pchote)
     * Pavel Penev (penev92)
+    * Reaperrr
     * Robert Pepperell (ytinasni)
     * ScottNZ
     * Tom Roostan (RoosterDragon)
 
 Also thanks to:
     * abmyii
+    * anvilvapre (anvilvapre)
     * Adam Valy (Tschokky)
     * Akseli Virtanen (RAGEQUIT)
     * Alexander Fast (mizipzor)
@@ -37,6 +39,7 @@ Also thanks to:
     * Arik Lirette (Angusm3)
     * Barnaby Smith (mvi)
     * Bellator
+    * Bernd Stellwag (burned42)
     * Biofreak
     * Braxton Williams (Buddytex)
     * Brendan Gluth (Mechanical_Man)
@@ -46,6 +49,7 @@ Also thanks to:
     * Chris Cameron (Vesuvian)
     * Chris Grant (Unit158)
     * Christer Ulfsparre (Holloweye)
+    * Christoph Lahner (chlah)
     * clem
     * Cody Brittain (Generalcamo)
     * Constantin Helmig (CH4Code)
@@ -58,6 +62,7 @@ Also thanks to:
     * DeadlySurprise
     * Dmitri Suvorov (suvjunmd)
     * dtluna
+    * Eduardo Cáceres (eduherminio)
     * Erasmus Schroder (rasco)
     * Eric Bajumpaa (SteelPhase)
     * Evgeniy Sergeev (evgeniysergeev)
@@ -69,12 +74,14 @@ Also thanks to:
     * Glenn Martin Jensen (Baxxster)
     * Gordon Martin (Happy0)
     * Guido Lipke (LipkeGu)
+    * Guillermo Cuenca (Wylli)
     * Hervé Matysiak (Herve-M)
     * Huw Pascoe
     * Ian T. Jacobsen (Smilex)
     * Imago
     * Iran
     * Ishan Bhargava (ishantheperson)
+    * Ivaylo Draganov (dragunoff)
     * Jacob Dufault (jacobdufault)
     * James Dunne (jsd)
     * James Gilbert (DSUK)
@@ -113,6 +120,7 @@ Also thanks to:
     * Mike Gagné (AngryBirdz)
     * Muh
     * Mustafa Alperen Seki (MustaphaTR)
+    * Nathan Nichols (cracksmoka420)
     * Neil Shivkar (havok13888)
     * Nikolay Fomin (netnazgul)
     * Nooze
@@ -135,13 +143,14 @@ Also thanks to:
     * Rikhardur Bjarni Einarsson (WolfGaming)
     * Sascha Biedermann (bidifx)
     * Sean Hunt (coppro)
-    * Sebastien Kerguen (xanax)
     * Shawn Collins (UberWaffe)
     * Simon Verbeke (Saticmotion)
     * Stuart McHattie (SDJMcHattie)
     * Taryn Hill (Phrohdoh)
     * Teemu Nieminen (Temeez)
+    * Thomas Christlieb (ThomasChr)
     * Tim Mylemans (gecko)
+    * Tinix
     * Tirili
     * Tomas Einarsson (Mesacer)
     * Tom van Leth (tovl)
@@ -173,9 +182,17 @@ under the MIT license.
 Using FuzzyLogicLibrary (fuzzynet) by Dmitry
 Kaluzhny and released under the GNU GPL terms.
 
-Using Open.Nat by Lucas Ontivero, based on the work
-of Alan McGovern and Ben Motmans and distributed
-under the MIT license.
+Using Mono.Nat by Alan McGovern, Ben Motmans,
+Nicholas Terry distributed under the MIT license.
+
+Using MP3Sharp by Robert Bruke and Zane Wagner
+licensed under the GNU LGPL Version 3.
+
+Using TagLib# by Stephen Shaw licensed under the
+GNU LGPL Version 2.1.
+
+Using NVorbis by Andrew Ward distributed under
+the MIT license.
 
 Using ICSharpCode.SharpZipLib initially by Mike
 Krueger and distributed under the GNU GPL terms.
@@ -191,6 +208,12 @@ distributed under MIT License.
 
 Using ANGLE distributed under the BS3 3-Clause license.
 
+Using Pfim developed by Nick Babcock
+distributed under the MIT license.
+
+Using Linguini by the Space Station 14 team
+licensed under Apache and MIT terms.
+
 This site or product includes IP2Location LITE data
 available from http://www.ip2location.com.
 

CODE_OF_CONDUCT.md

@@ -56,8 +56,8 @@ further defined and clarified by project maintainers.
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
 reported by private-messaging a project team member (users with a + in front
-of their name) via our IRC channel (#openra on freenode –
-[webchat](http://webchat.freenode.net/?channels=openra)). All
+of their name) via our IRC channel (#openra on Libera –
+[webchat](https://web.libera.chat/#openra)). All
 complaints will be reviewed and investigated and will result in a response that
 is deemed necessary and appropriate to the circumstances. The project team is
 obligated to maintain confidentiality with regard to the reporter of an incident.

Directory.Build.props

@@ -0,0 +1,60 @@
+<Project>
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+    <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <Optimize>true</Optimize>
+    <LangVersion>9</LangVersion>
+    <DebugSymbols>true</DebugSymbols>
+    <EngineRootPath Condition="'$(EngineRootPath)' == ''">..</EngineRootPath>
+    <OutputPath>$(EngineRootPath)/bin</OutputPath>
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <ExternalConsole>false</ExternalConsole>
+    <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
+    <Nullable>disable</Nullable>
+    <Product>OpenRA</Product>
+    <Copyright>Copyright (c) The OpenRA Developers and Contributors</Copyright>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <TargetFramework Condition="'$(MSBuildRuntimeType)'!='Mono'">net6.0</TargetFramework>
+    <TargetFramework Condition="'$(MSBuildRuntimeType)'=='Mono'">netstandard2.1</TargetFramework>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <TargetPlatform Condition="$([MSBuild]::IsOsPlatform('Windows'))">win-x64</TargetPlatform>
+    <TargetPlatform Condition="$([MSBuild]::IsOsPlatform('Linux'))">linux-x64</TargetPlatform>
+    <TargetPlatform Condition="$([MSBuild]::IsOsPlatform('OSX'))">osx-x64</TargetPlatform>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <Optimize>false</Optimize>
+    <!-- Enable only for Debug builds to improve compile-time performance for Release builds -->
+    <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
+    <!-- Enabling GenerateDocumentationFile is required for IDE0005 (Remove unnecessary import)
+      rule to run in command line builds. https://github.com/dotnet/roslyn/issues/41640
+      Enable only for Debug builds to improve compile-time performance for Release builds -->
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!-- Work around an issue where Rider does not detect files in the project root using the default glob -->
+    <Compile Include="**/*.cs" Exclude="$(DefaultItemExcludes)" />
+  </ItemGroup>
+
+  <Target Name="DisableAnalyzers" BeforeTargets="CoreCompile" Condition="'$(Configuration)'=='Release'">
+    <!-- Disable code style analysis on Release builds to improve compile-time performance -->
+    <ItemGroup Condition="'$(Configuration)'=='Release'">
+      <Analyzer Remove="@(Analyzer)" />
+    </ItemGroup>
+  </Target>
+
+  <!-- StyleCop/Roslynator -->
+  <ItemGroup>
+    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.435" PrivateAssets="All" />
+    <!-- Roslynator analyzers fail to run under Mono (AD0001) -->
+    <PackageReference Include="Roslynator.Analyzers" Version="4.2.0" PrivateAssets="All" Condition="'$(MSBuildRuntimeType)'!='Mono'" />
+  </ItemGroup>
+</Project>

INSTALL.md

@@ -8,104 +8,76 @@ Windows
 
 Compiling OpenRA requires the following dependencies:
 * [Windows PowerShell >= 4.0](http://microsoft.com/powershell) (included by default in recent Windows 10 versions)
-* [.NET Framework 4.7.2 (Developer Pack)](https://dotnet.microsoft.com/download/dotnet-framework/net472) (or via Visual Studio 2017)
-* [.NET Core 2.2 SDK](https://dotnet.microsoft.com/download/dotnet-core/2.2) (or via Visual Studio 2017)
+* [.NET 6 SDK](https://dotnet.microsoft.com/download/dotnet/6.0) (or via Visual Studio)
 
-
-To compile OpenRA, open the `OpenRA.sln` solution in the main folder, build it from the command-line with MSBuild or use the Makefile analogue command `make all` scripted in PowerShell syntax.
+To compile OpenRA, open the `OpenRA.sln` solution in the main folder, build it from the command-line with `dotnet` or use the Makefile analogue command `make all` scripted in PowerShell syntax.
 
 Run the game with `launch-game.cmd`. It can be handed arguments that specify the exact mod one wishes to run, for example, run `launch-game.cmd Game.Mod=ra` to launch Red Alert, `launch-game.cmd Game.Mod=cnc` to start Tiberian dawn or `launch-game.cmd Game.Mod=d2k` to launch Dune 2000.
 
 Linux
 =====
 
-Mono, version 5.18 or later, is required to compile OpenRA. You can add the [upstream mono repository](https://www.mono-project.com/download/stable/#download-lin) for your distro to obtain the latest version if your system packages are not sufficient.
+.NET 6 or Mono (version 6.12 or later) is required to compile OpenRA. We recommend using .NET 6 when possible, as Mono is poorly packaged by most Linux distributions (e.g. missing the required `msbuild` toolchain), and has been deprecated as a standalone project.
 
-To compile OpenRA, run `make` from the command line. After this one can run the game with `./launch-game.sh`. It is also possible to specify the mod you wish to run from the command line, e.g. with `./launch-game.sh Game.Mod=ts` if you wish to try the experimental Tiberian Sun mod.
+The [.NET 6 download page](https://dotnet.microsoft.com/download/dotnet/6.0) provides repositories for various package managers and binary releases for several architectures. If you prefer to use Mono, we suggest adding the [upstream repository](https://www.mono-project.com/download/stable/#download-lin) for your distro to obtain the latest version and the `msbuild` toolchain.
+
+To compile OpenRA, run `make` from the command line (or `make RUNTIME=mono` if using Mono). After this one can run the game with `./launch-game.sh`. It is also possible to specify the mod you wish to run from the command line, e.g. with `./launch-game.sh Game.Mod=ts` if you wish to try the experimental Tiberian Sun mod.
 
 The default behaviour on the x86_64 architecture is to download several pre-compiled native libraries using the Nuget packaging manager. If you prefer to use system libraries, compile instead using `make TARGETPLATFORM=unix-generic`.
 
-If you choose to use system libraries, or your system is not x86_64, you will need to install the following using your system package manager:
-* [SDL 2](http://www.libsdl.org/download-2.0.php)
-* [FreeType](http://gnuwin32.sourceforge.net/packages/freetype.htm)
-* [OpenAL](http://kcat.strangesoft.net/openal.html)
-* [liblua 5.1](http://luabinaries.sourceforge.net/download.html)
+If you choose to use system libraries, or your system is not x86_64, you will need to install [SDL 2](https://www.libsdl.org/download-2.0.php), [FreeType](http://gnuwin32.sourceforge.net/packages/freetype.htm), [OpenAL](https://openal-soft.org/), and [liblua 5.1](http://luabinaries.sourceforge.net/download.html) before compiling OpenRA.
 
-Type `sudo make install` for system-wide installation. Run `sudo make install-linux-shortcuts` to get startup scripts, icons and desktop files. You can then run the Red Alert by executing the `openra-ra` command, the Dune 2000 mod by running the `openra-d2k` command and Tiberian Dawn by the `openra-cnc` command. Alternatively, you can also run these mods by clicking on their desktop shortcuts if you ran `sudo make install-linux-shortcuts`.
+These can be installed using your package manager on various distros:
 
-Arch Linux
-----------
-
-It is important to note there is an unofficial [`openra-git`](https://aur.archlinux.org/packages/openra-git) package in the Arch User Repository (AUR) of Arch Linux. If manually compiling is the way you wish to go the build and runtime dependencies can be installed with:
+<details><summary>Arch Linux</summary>
 
 ```
-sudo pacman -S mono openal libgl freetype2 sdl2 lua51 xdg-utils zenity
+sudo pacman -S openal libgl freetype2 sdl2 lua51
 ```
-
-Debian/Ubuntu
--------------
-
-:warning: The `mono` packages in the Ubuntu < 19.04 and Debian < 10 repositories are too old to support OpenRA. :warning:
-
-See the instructions under the *Linux* section above to upgrade `mono` using the upstream releases if needed.
+</details>
+<details><summary>Debian/Ubuntu</summary>
 
 ```
-sudo apt install mono-devel libfreetype6 libopenal1 liblua5.1-0 libsdl2-2.0-0 xdg-utils zenity wget
+sudo apt install libfreetype6 libopenal1 liblua5.1-0 libsdl2-2.0-0
 ```
-
-Fedora
-------
-
-:warning: The `mono` packages in the Fedora repositories are too old to support OpenRA. :warning:
-
-See the instructions under the *Linux* section above to upgrade `mono` using the upstream releases.
-
+</details>
+<details><summary>Fedora</summary>
 
 ```
-sudo dnf install "pkgconfig(mono)" SDL2 freetype "lua = 5.1" openal-soft xdg-utils zenity
+sudo dnf install SDL2 freetype "lua = 5.1" openal-soft
 ```
-
-Gentoo
-------
+</details>
+<details><summary>Gentoo</summary>
 
 ```
-sudo emerge -av dev-lang/mono dev-dotnet/libgdiplus media-libs/freetype:2 media-libs/libsdl2 media-libs/openal virtual/jpeg virtual/opengl '=dev-lang/lua-5.1.5*' x11-misc/xdg-utils gnome-extra/zenity
+sudo emerge -av media-libs/freetype:2 media-libs/libsdl2 media-libs/openal virtual/opengl '=dev-lang/lua-5.1.5*'
 ```
-
-Mageia
-------
+</details>
+<details><summary>Mageia</summary>
 
 ```
-sudo dnf install "pkgconfig(mono)" SDL2 freetype "lib*lua5.1" "lib*freetype2" "lib*sdl2.0_0" openal-soft xdg-utils zenity
+sudo dnf install SDL2 freetype "lib*lua5.1" "lib*freetype2" "lib*sdl2.0_0" openal-soft
 ```
-
-openSUSE
---------
+</details>
+<details><summary>openSUSE</summary>
 
 ```
-sudo zypper in mono-devel openal-soft freetype2 SDL2 lua51 xdg-utils zenity
+sudo zypper in openal-soft freetype2 SDL2 lua51
 ```
-
-Red Hat Enterprise Linux (and rebuilds, e.g. CentOS)
-----------------------------------------------------
-
+</details>
+<details><summary>Red Hat Enterprise Linux (and rebuilds, e.g. CentOS)</summary>
 The EPEL repository is required in order for the following command to run properly.
 
 ```
-sudo yum install "pkgconfig(mono)" SDL2 freetype "lua = 5.1" openal-soft xdg-utils zenity
+sudo yum install SDL2 freetype "lua = 5.1" openal-soft
 ```
+</details>
+
+Type `sudo make install` for system-wide installation. Run `sudo make install-linux-shortcuts` to get startup scripts, icons and desktop files. You can then run the Red Alert by executing the `openra-ra` command, the Dune 2000 mod by running the `openra-d2k` command and Tiberian Dawn by the `openra-cnc` command. Alternatively, you can also run these mods by clicking on their desktop shortcuts if you ran `sudo make install-linux-shortcuts`.
 
 macOS
 =====
 
-Before compiling OpenRA you must install the following dependencies:
-* [Mono >= 5.18](https://www.mono-project.com/download/stable/#download-mac)
-
-To compile OpenRA, run `make` from the command line. Run with `./launch-game.sh`.
-
-The default behaviour is to download several pre-compiled native libraries using the Nuget packaging manager. If you prefer to use system libraries, compile instead using `make TARGETPLATFORM=unix-generic`. If you choose to use system libraries you will need to install:
-* [SDL 2](http://www.libsdl.org/download-2.0.php) (`brew install sdl2`)
-* [FreeType](http://gnuwin32.sourceforge.net/packages/freetype.htm) (`brew install freetype`)
-* [OpenAL](http://kcat.strangesoft.net/openal.html) (`brew install openal-soft`)
-* [liblua 5.1](http://luabinaries.sourceforge.net/download.html) (`brew install lua@5.1`)
+[.NET 6](https://dotnet.microsoft.com/download/dotnet/6.0) or [Mono](https://www.mono-project.com/download/stable/#download-mac) (version 6.12 or later) is required to compile OpenRA. We recommend using .NET 6 unless you are running a very old version of macOS (10.9 through 10.14).
 
+To compile OpenRA, run `make` from the command line (or `make RUNTIME=mono` if using Mono). Run with `./launch-game.sh`.

Makefile

@@ -1,42 +1,40 @@
 ############################# INSTRUCTIONS #############################
 #
 # to compile, run:
-#   make [DEBUG=true]
+#   make
+#
+# to compile using Mono (version 6.12 or greater) instead of .NET 6, run:
+#   make RUNTIME=mono
 #
 # to compile using system libraries for native dependencies, run:
-#   make [DEBUG=true] TARGETPLATFORM=unix-generic
+#   make [RUNTIME=net6] TARGETPLATFORM=unix-generic
 #
 # to check the official mods for erroneous yaml files, run:
-#   make test
+#   make [RUNTIME=net6] test
 #
 # to check the engine and official mod dlls for code style violations, run:
-#   make check
+#   make [RUNTIME=net6] check
 #
 # to compile and install Red Alert, Tiberian Dawn, and Dune 2000, run:
-#   make [prefix=/foo] [bindir=/bar/bin] install
+#   make [RUNTIME=net6] [prefix=/foo] [bindir=/bar/bin] install
 #
-# to install Linux startup scripts, desktop files, icons, and MIME metadata
+# to compile and install Red Alert, Tiberian Dawn, and Dune 2000
+# using system libraries for native dependencies, run:
+#   make [prefix=/foo] [bindir=/bar/bin] TARGETPLATFORM=unix-generic install
+#
+# to install FreeDesktop startup scripts, desktop files, icons, and MIME metadata
 #   make install-linux-shortcuts
 #
-# to install Linux AppStream metadata
+# to install FreeDesktop AppStream metadata
 #   make install-linux-appdata
 #
+# to install the Unix man page
+#   make install-man
+#
 # for help, run:
 #   make help
 #
 
-############################## TOOLCHAIN ###############################
-#
-# List of .NET assemblies that we can guarantee exist
-WHITELISTED_OPENRA_ASSEMBLIES = OpenRA.exe OpenRA.Utility.exe OpenRA.Server.exe OpenRA.Platforms.Default.dll OpenRA.Game.dll OpenRA.Mods.Common.dll OpenRA.Mods.Cnc.dll OpenRA.Mods.D2k.dll
-
-# These are explicitly shipped alongside our core files by the packaging script
-WHITELISTED_THIRDPARTY_ASSEMBLIES = ICSharpCode.SharpZipLib.dll FuzzyLogicLibrary.dll Eluant.dll BeaconLib.dll Open.Nat.dll SDL2-CS.dll OpenAL-CS.Core.dll DiscordRPC.dll Newtonsoft.Json.dll
-
-# These are shipped in our custom minimal mono runtime and also available in the full system-installed .NET/mono stack
-# This list *must* be kept in sync with the files packaged by the AppImageSupport and OpenRALauncherOSX repositories
-WHITELISTED_CORE_ASSEMBLIES = mscorlib.dll System.dll System.Configuration.dll System.Core.dll System.Numerics.dll System.Security.dll System.Xml.dll Mono.Security.dll netstandard.dll
-
 ######################### UTILITIES/SETTINGS ###########################
 #
 # Install locations for local installs and downstream packaging
@@ -48,125 +46,165 @@ bindir ?= $(prefix)/bin
 libdir ?= $(prefix)/lib
 gameinstalldir ?= $(libdir)/openra
 
-BIN_INSTALL_DIR = $(DESTDIR)$(bindir)
-DATA_INSTALL_DIR = $(DESTDIR)$(datadir)
-OPENRA_INSTALL_DIR = $(DESTDIR)$(gameinstalldir)
-
 # Toolchain
 CWD = $(shell pwd)
 MSBUILD = msbuild -verbosity:m -nologo
+DOTNET = dotnet
 MONO = mono
 RM = rm
 RM_R = $(RM) -r
 RM_F = $(RM) -f
 RM_RF = $(RM) -rf
 
-VERSION = $(shell git name-rev --name-only --tags --no-undefined HEAD 2>/dev/null || echo git-`git rev-parse --short HEAD`)
+RUNTIME ?= net6
+CONFIGURATION ?= Release
+DOTNET_RID = $(shell ${DOTNET} --info | grep RID: | cut -w -f3)
+ARCH_X64 = $(shell echo ${DOTNET_RID} | grep x64)
+
+# Only for use in target version:
+VERSION := $(shell git name-rev --name-only --tags --no-undefined HEAD 2>/dev/null || (c=$$(git rev-parse --short HEAD 2>/dev/null) && echo git-$$c))
 
 # Detect target platform for dependencies if not given by the user
 ifndef TARGETPLATFORM
 UNAME_S := $(shell uname -s)
 UNAME_M := $(shell uname -m)
 ifeq ($(UNAME_S),Darwin)
+ifeq ($(ARCH_X64),)
+TARGETPLATFORM = osx-arm64
+else
 TARGETPLATFORM = osx-x64
+endif
 else
 ifeq ($(UNAME_M),x86_64)
 TARGETPLATFORM = linux-x64
 else
+ifeq ($(UNAME_M),aarch64)
+TARGETPLATFORM = linux-arm64
+else
 TARGETPLATFORM = unix-generic
 endif
 endif
 endif
-
-OPENRA_UTILITY = ENGINE_DIR=".." $(MONO) --debug bin/OpenRA.Utility.exe
+endif
 
 ##################### DEVELOPMENT BUILDS AND TESTS #####################
 #
 all:
-	@command -v $(firstword $(MSBUILD)) >/dev/null || (echo "OpenRA requires the '$(MSBUILD)' tool provided by Mono >= 5.18."; exit 1)
-	@$(MSBUILD) -t:Build -restore -p:Configuration=Release -p:TargetPlatform=$(TARGETPLATFORM)
+	@echo "Compiling in ${CONFIGURATION} mode..."
+ifeq ($(RUNTIME), mono)
+	@command -v $(firstword $(MSBUILD)) >/dev/null || (echo "OpenRA requires the '$(MSBUILD)' tool provided by Mono >= 6.12."; exit 1)
+	@$(MSBUILD) -t:Build -restore -p:Configuration=${CONFIGURATION} -p:TargetPlatform=$(TARGETPLATFORM)
+else
+	@$(DOTNET) build -c ${CONFIGURATION} -nologo -p:TargetPlatform=$(TARGETPLATFORM)
+endif
 ifeq ($(TARGETPLATFORM), unix-generic)
 	@./configure-system-libraries.sh
 endif
 	@./fetch-geoip.sh
 
+# dotnet clean and msbuild -t:Clean leave files that cause problems when switching between mono/dotnet
+# Deleting the intermediate / output directories ensures the build directory is actually clean
 clean:
-	@-$(RM_RF) ./bin ./*/bin ./*/obj
-	@$(MSBUILD) -t:Clean
+	@-$(RM_RF) ./bin ./*/obj
 	@-$(RM_F) IP2LOCATION-LITE-DB1.IPV6.BIN.ZIP
 
 check:
 	@echo
-	@echo "Compiling in debug mode..."
-	@$(MSBUILD) -t:build -restore -p:Configuration=Debug
-	@echo
-	@echo "Checking runtime assemblies..."
-	@$(OPENRA_UTILITY) all --check-runtime-assemblies $(WHITELISTED_OPENRA_ASSEMBLIES) $(WHITELISTED_THIRDPARTY_ASSEMBLIES) $(WHITELISTED_CORE_ASSEMBLIES)
+	@echo "Compiling in Debug mode..."
+ifeq ($(RUNTIME), mono)
+	@$(MSBUILD) -t:clean\;build -restore -p:Configuration=Debug -warnaserror -p:TargetPlatform=$(TARGETPLATFORM)
+else
+	@$(DOTNET) clean -c Debug --nologo --verbosity minimal
+	@$(DOTNET) build -c Debug -nologo -warnaserror -p:TargetPlatform=$(TARGETPLATFORM)
+endif
+ifeq ($(TARGETPLATFORM), unix-generic)
+	@./configure-system-libraries.sh
+endif
 	@echo
 	@echo "Checking for explicit interface violations..."
-	@$(OPENRA_UTILITY) all --check-explicit-interfaces
+	@./utility.sh all --check-explicit-interfaces
 	@echo
 	@echo "Checking for incorrect conditional trait interface overrides..."
-	@$(OPENRA_UTILITY) all --check-conditional-trait-interface-overrides
+	@./utility.sh all --check-conditional-trait-interface-overrides
 
 check-scripts:
 	@echo
 	@echo "Checking for Lua syntax errors..."
-	@luac -p $(shell find mods/*/maps/* -iname '*.lua')
-	@luac -p $(shell find lua/* -iname '*.lua')
-	@luac -p $(shell find mods/*/bits/scripts/* -iname '*.lua')
+	@find mods/*/maps/ mods/*/scripts/ -iname "*.lua" -print0 | xargs -0n1 luac -p
 
 test: all
 	@echo
 	@echo "Testing Tiberian Sun mod MiniYAML..."
-	@$(OPENRA_UTILITY) ts --check-yaml
+	@./utility.sh ts --check-yaml
 	@echo
 	@echo "Testing Dune 2000 mod MiniYAML..."
-	@$(OPENRA_UTILITY) d2k --check-yaml
+	@./utility.sh d2k --check-yaml
 	@echo
 	@echo "Testing Tiberian Dawn mod MiniYAML..."
-	@$(OPENRA_UTILITY) cnc --check-yaml
+	@./utility.sh cnc --check-yaml
 	@echo
 	@echo "Testing Red Alert mod MiniYAML..."
-	@$(OPENRA_UTILITY) ra --check-yaml
+	@./utility.sh ra --check-yaml
+
+tests:
+	@dotnet build OpenRA.Test/OpenRA.Test.csproj -c Debug --nologo -p:TargetPlatform=$(TARGETPLATFORM)
+	@echo
+	@dotnet test bin/OpenRA.Test.dll --test-adapter-path:.
 
 ############# LOCAL INSTALLATION AND DOWNSTREAM PACKAGING ##############
 #
 version: VERSION mods/ra/mod.yaml mods/cnc/mod.yaml mods/d2k/mod.yaml mods/ts/mod.yaml mods/modcontent/mod.yaml mods/all/mod.yaml
-	@sh -c '. ./packaging/functions.sh; set_engine_version $(VERSION) .'
-	@sh -c '. ./packaging/functions.sh; set_mod_version $(VERSION) mods/ra/mod.yaml mods/cnc/mod.yaml mods/d2k/mod.yaml mods/ts/mod.yaml mods/modcontent/mod.yaml mods/all/mod.yaml'
+ifeq ($(VERSION),)
+	$(error Unable to determine new version (requires git or override of variable VERSION))
+endif
+	@sh -c '. ./packaging/functions.sh; set_engine_version "$(VERSION)" .'
+	@sh -c '. ./packaging/functions.sh; set_mod_version "$(VERSION)" mods/ra/mod.yaml mods/cnc/mod.yaml mods/d2k/mod.yaml mods/ts/mod.yaml mods/modcontent/mod.yaml mods/all/mod.yaml'
 
 install:
-	@sh -c '. ./packaging/functions.sh; install_assemblies_mono $(CWD) $(OPENRA_INSTALL_DIR) $(TARGETPLATFORM) True True True'
-	@sh -c '. ./packaging/functions.sh; install_data $(CWD) $(OPENRA_INSTALL_DIR) cnc d2k ra'
+	@sh -c '. ./packaging/functions.sh; install_assemblies $(CWD) $(DESTDIR)$(gameinstalldir) $(TARGETPLATFORM) $(RUNTIME) True True True'
+	@sh -c '. ./packaging/functions.sh; install_data $(CWD) $(DESTDIR)$(gameinstalldir) cnc d2k ra'
 
 install-linux-shortcuts:
-	@sh -c '. ./packaging/functions.sh; install_linux_shortcuts $(CWD) $(OPENRA_INSTALL_DIR) $(BIN_INSTALL_DIR) $(DATA_INSTALL_DIR) $(VERSION) cnc d2k ra'
+	@sh -c '. ./packaging/functions.sh; install_linux_shortcuts $(CWD) "$(DESTDIR)" "$(gameinstalldir)" "$(bindir)" "$(datadir)" "$(shell head -n1 VERSION)" cnc d2k ra'
 
 install-linux-appdata:
-	@sh -c '. ./packaging/functions.sh; install_linux_appdata $(CWD) $(DATA_INSTALL_DIR) cnc d2k ra'
+	@sh -c '. ./packaging/functions.sh; install_linux_appdata $(CWD) "$(DESTDIR)" "$(datadir)" cnc d2k ra'
+
+install-man: all
+	@mkdir -p $(DESTDIR)$(mandir)/man6/
+	@./utility.sh all --man-page > $(DESTDIR)$(mandir)/man6/openra.6
 
 help:
 	@echo 'to compile, run:'
-	@echo '  make [DEBUG=true]'
+	@echo '  make'
+	@echo
+	@echo 'to compile using Mono (version 6.12 or greater) instead of .NET 6, run:'
+	@echo '  make RUNTIME=mono'
 	@echo
 	@echo 'to compile using system libraries for native dependencies, run:'
-	@echo '  make [DEBUG=true] TARGETPLATFORM=unix-generic'
+	@echo '  make [RUNTIME=net6] TARGETPLATFORM=unix-generic'
 	@echo
 	@echo 'to check the official mods for erroneous yaml files, run:'
-	@echo '  make test'
+	@echo '  make [RUNTIME=net6] [TREAT_WARNINGS_AS_ERRORS=false] test'
 	@echo
 	@echo 'to check the engine and official mod dlls for code style violations, run:'
-	@echo '  make test'
+	@echo '  make [RUNTIME=net6] check'
 	@echo
 	@echo 'to compile and install Red Alert, Tiberian Dawn, and Dune 2000 run:'
-	@echo '  make [prefix=/foo] install'
+	@echo '  make [RUNTIME=net6] [prefix=/foo] [TARGETPLATFORM=unix-generic] install'
 	@echo
-	@echo 'to install Linux startup scripts, desktop files, icons, and MIME metadata'
+	@echo 'to compile and install Red Alert, Tiberian Dawn, and Dune 2000'
+	@echo 'using system libraries for native dependencies, run:'
+	@echo '   make [RUNTIME=net6] [prefix=/foo] [bindir=/bar/bin] TARGETPLATFORM=unix-generic install'
+	@echo
+	@echo 'to install FreeDesktop startup scripts, desktop files, icons, and MIME metadata'
 	@echo '  make install-linux-shortcuts'
 	@echo
-	@echo 'to install Linux AppStream metadata'
+	@echo 'to install FreeDesktop AppStream metadata'
 	@echo '  make install-linux-appdata'
+	@echo
+	@echo 'to install a Unix man page'
+	@echo '  make install-man'
 
 ########################### MAKEFILE SETTINGS ##########################
 #
@@ -174,4 +212,4 @@ help:
 
 .SUFFIXES:
 
-.PHONY: all clean check check-scripts test version install install-linux-shortcuts install-linux-appdata help
+.PHONY: all clean check check-scripts test version install install-linux-shortcuts install-linux-appdata install-man help

OpenRA.Game/Activities/Activity.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -53,15 +53,15 @@ namespace OpenRA.Activities
 		Activity childActivity;
 		protected Activity ChildActivity
 		{
-			get { return SkipDoneActivities(childActivity); }
-			private set { childActivity = value; }
+			get => SkipDoneActivities(childActivity);
+			private set => childActivity = value;
 		}
 
 		Activity nextActivity;
 		public Activity NextActivity
 		{
-			get { return SkipDoneActivities(nextActivity); }
-			private set { nextActivity = value; }
+			get => SkipDoneActivities(nextActivity);
+			private set => nextActivity = value;
 		}
 
 		internal static Activity SkipDoneActivities(Activity first)
@@ -74,19 +74,19 @@ namespace OpenRA.Activities
 			// drop valid activities queued after it. Walk the queue until we find a valid activity or
 			// (more likely) run out of activities.
 			while (first != null && first.State == ActivityState.Done)
-				first = first.NextActivity;
+				first = first.nextActivity;
 
 			return first;
 		}
 
 		public bool IsInterruptible { get; protected set; }
 		public bool ChildHasPriority { get; protected set; }
-		public bool IsCanceling { get { return State == ActivityState.Canceling; } }
+		public bool IsCanceling => State == ActivityState.Canceling;
 		bool finishing;
 		bool firstRunCompleted;
 		bool lastRun;
 
-		public Activity()
+		protected Activity()
 		{
 			IsInterruptible = true;
 			ChildHasPriority = true;
@@ -95,7 +95,7 @@ namespace OpenRA.Activities
 		public Activity TickOuter(Actor self)
 		{
 			if (State == ActivityState.Done)
-				throw new InvalidOperationException("Actor {0} attempted to tick activity {1} after it had already completed.".F(self, GetType()));
+				throw new InvalidOperationException($"Actor {self} attempted to tick activity {GetType()} after it had already completed.");
 
 			if (State == ActivityState.Queued)
 			{
@@ -105,7 +105,7 @@ namespace OpenRA.Activities
 			}
 
 			if (!firstRunCompleted)
-				throw new InvalidOperationException("Actor {0} attempted to tick activity {1} before running its OnFirstRun method.".F(self, GetType()));
+				throw new InvalidOperationException($"Actor {self} attempted to tick activity {GetType()} before running its OnFirstRun method.");
 
 			// Only run the parent tick when the child is done.
 			// We must always let the child finish on its own before continuing.
@@ -120,7 +120,8 @@ namespace OpenRA.Activities
 				lastRun = Tick(self);
 
 			// Avoid a single tick delay if the childactivity was just queued.
-			if (ChildActivity != null && ChildActivity.State == ActivityState.Queued)
+			var ca = ChildActivity;
+			if (ca != null && ca.State == ActivityState.Queued)
 			{
 				if (ChildHasPriority)
 					lastRun = TickChild(self) && finishing;
@@ -145,18 +146,22 @@ namespace OpenRA.Activities
 		}
 
 		/// <summary>
+		/// <para>
 		/// Called every tick to run activity logic. Returns false if the activity should
 		/// remain active, or true if it is complete. Cancelled activities must ensure they
 		/// return the actor to a consistent state before returning true.
-		///
+		/// </para>
+		/// <para>
 		/// Child activities can be queued using QueueChild, and these will be ticked
 		/// instead of the parent while they are active. Activities that need to run logic
 		/// in parallel with child activities should set ChildHasPriority to false and
 		/// manually call TickChildren.
-		///
+		/// </para>
+		/// <para>
 		/// Queuing one or more child activities and returning true is valid, and causes
 		/// the activity to be completed immediately (without ticking again) once the
 		/// children have completed.
+		/// </para>
 		/// </summary>
 		public virtual bool Tick(Actor self)
 		{
@@ -206,25 +211,26 @@ namespace OpenRA.Activities
 
 		public void Queue(Activity activity)
 		{
-			if (NextActivity != null)
-				NextActivity.Queue(activity);
-			else
-				NextActivity = activity;
+			var it = this;
+			while (it.nextActivity != null)
+				it = it.nextActivity;
+			it.nextActivity = activity;
 		}
 
 		public void QueueChild(Activity activity)
 		{
-			if (ChildActivity != null)
-				ChildActivity.Queue(activity);
+			if (childActivity != null)
+				childActivity.Queue(activity);
 			else
-				ChildActivity = activity;
+				childActivity = activity;
 		}
 
 		/// <summary>
-		/// Prints the activity tree, starting from the top or optionally from a given origin.
-		///
+		/// <para>Prints the activity tree, starting from the top or optionally from a given origin.</para>
+		/// <para>
 		/// Call this method from any place that's called during a tick, such as the Tick() method itself or
 		/// the Before(First|Last)Run() methods. The origin activity will be marked in the output.
+		/// </para>
 		/// </summary>
 		/// <param name="self">The actor performing this activity.</param>
 		/// <param name="origin">Activity from which to start traversing, and which to mark. If null, mark the calling activity, and start traversal from the top.</param>
@@ -269,15 +275,21 @@ namespace OpenRA.Activities
 
 		public IEnumerable<T> ActivitiesImplementing<T>(bool includeChildren = true) where T : IActivityInterface
 		{
-			if (includeChildren && ChildActivity != null)
-				foreach (var a in ChildActivity.ActivitiesImplementing<T>())
-					yield return a;
+			// Skips Done child and next activities
+			if (includeChildren)
+			{
+				var ca = ChildActivity;
+				if (ca != null)
+					foreach (var a in ca.ActivitiesImplementing<T>())
+						yield return a;
+			}
 
 			if (this is T)
 				yield return (T)(object)this;
 
-			if (NextActivity != null)
-				foreach (var a in NextActivity.ActivitiesImplementing<T>())
+			var na = NextActivity;
+			if (na != null)
+				foreach (var a in na.ActivitiesImplementing<T>())
 					yield return a;
 		}
 	}

OpenRA.Game/Activities/CallFunc.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,11 +22,11 @@ namespace OpenRA.Activities
 			IsInterruptible = interruptible;
 		}
 
-		Action a;
+		readonly Action a;
 
 		public override bool Tick(Actor self)
 		{
-			a?.Invoke();
+			a.Invoke();
 			return true;
 		}
 	}

OpenRA.Game/Actor.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
 using Eluant;
@@ -23,9 +24,21 @@ using OpenRA.Traits;
 
 namespace OpenRA
 {
+	[Flags]
+	public enum SystemActors
+	{
+		Player = 0,
+		EditorPlayer = 1,
+		World = 2,
+		EditorWorld = 4
+	}
+
 	public sealed class Actor : IScriptBindable, IScriptNotifyBind, ILuaTableBinding, ILuaEqualityBinding, ILuaToStringBinding, IEquatable<Actor>, IDisposable
 	{
-		internal struct SyncHash
+		/// <summary>Value used to represent an invalid token.</summary>
+		public const int InvalidConditionToken = -1;
+
+		internal readonly struct SyncHash
 		{
 			public readonly ISync Trait;
 			readonly Func<object, int> hashFunction;
@@ -48,57 +61,54 @@ namespace OpenRA
 		Activity currentActivity;
 		public Activity CurrentActivity
 		{
-			get { return Activity.SkipDoneActivities(currentActivity); }
-			private set { currentActivity = value; }
+			get => Activity.SkipDoneActivities(currentActivity);
+			private set => currentActivity = value;
 		}
 
 		public int Generation;
 		public Actor ReplacedByActor;
 
-		public IEffectiveOwner EffectiveOwner { get; private set; }
-		public IOccupySpace OccupiesSpace { get; private set; }
-		public ITargetable[] Targetables { get; private set; }
-
-		public bool IsIdle { get { return CurrentActivity == null; } }
-		public bool IsDead { get { return Disposed || (health != null && health.IsDead); } }
-
-		public CPos Location { get { return OccupiesSpace.TopLeft; } }
-		public WPos CenterPosition { get { return OccupiesSpace.CenterPosition; } }
-
-		public WRot Orientation
+		public IEffectiveOwner EffectiveOwner { get; }
+		public IOccupySpace OccupiesSpace { get; }
+		public ITargetable[] Targetables { get; }
+		public IEnumerable<ITargetablePositions> EnabledTargetablePositions { get; }
+		readonly ICrushable[] crushables;
+		public ICrushable[] Crushables
 		{
-			get
-			{
-				return facing != null ? facing.Orientation : WRot.None;
-			}
+			get => crushables ?? throw new InvalidOperationException($"Crushables for {Info.Name} are not initialized.");
 		}
 
-		/// <summary>Value used to represent an invalid token.</summary>
-		public static readonly int InvalidConditionToken = -1;
+		public bool IsIdle => CurrentActivity == null;
+		public bool IsDead => Disposed || (health != null && health.IsDead);
 
-		class ConditionState
+		public CPos Location => OccupiesSpace.TopLeft;
+		public WPos CenterPosition => OccupiesSpace.CenterPosition;
+
+		public WRot Orientation => facing?.Orientation ?? WRot.None;
+
+		sealed class ConditionState
 		{
 			/// <summary>Delegates that have registered to be notified when this condition changes.</summary>
-			public readonly List<VariableObserverNotifier> Notifiers = new List<VariableObserverNotifier>();
+			public readonly List<VariableObserverNotifier> Notifiers = new();
 
 			/// <summary>Unique integers identifying granted instances of the condition.</summary>
-			public readonly HashSet<int> Tokens = new HashSet<int>();
+			public readonly HashSet<int> Tokens = new();
 		}
 
-		readonly Dictionary<string, ConditionState> conditionStates = new Dictionary<string, ConditionState>();
+		readonly Dictionary<string, ConditionState> conditionStates = new();
 
 		/// <summary>Each granted condition receives a unique token that is used when revoking.</summary>
-		readonly Dictionary<int, string> conditionTokens = new Dictionary<int, string>();
+		readonly Dictionary<int, string> conditionTokens = new();
 
 		int nextConditionToken = 1;
 
 		/// <summary>Cache of condition -> enabled state for quick evaluation of token counter conditions.</summary>
-		readonly Dictionary<string, int> conditionCache = new Dictionary<string, int>();
+		readonly Dictionary<string, int> conditionCache = new();
 
 		/// <summary>Read-only version of conditionCache that is passed to IConditionConsumers.</summary>
 		readonly IReadOnlyDictionary<string, int> readOnlyConditionCache;
 
-		internal SyncHash[] SyncHashes { get; private set; }
+		internal SyncHash[] SyncHashes { get; }
 
 		readonly IFacing facing;
 		readonly IHealth health;
@@ -110,10 +120,8 @@ namespace OpenRA
 		readonly IDefaultVisibility defaultVisibility;
 		readonly INotifyBecomingIdle[] becomingIdles;
 		readonly INotifyIdle[] tickIdles;
-		readonly IEnumerable<ITargetablePositions> enabledTargetablePositions;
-		WPos[] staticTargetablePositions;
+		readonly IEnumerable<WPos> enabledTargetableWorldPositions;
 		bool created;
-		bool setStaticTargetablePositions;
 
 		internal Actor(World world, string name, TypeDictionary initDict)
 		{
@@ -121,7 +129,7 @@ namespace OpenRA
 				.FirstOrDefault(i => i.Count() > 1);
 
 			if (duplicateInit != null)
-				throw new InvalidDataException("Duplicate initializer '{0}'".F(duplicateInit.Key.Name));
+				throw new InvalidDataException($"Duplicate initializer '{duplicateInit.Key.Name}'");
 
 			var init = new ActorInitializer(this, initDict);
 
@@ -142,7 +150,6 @@ namespace OpenRA
 
 				Info = world.Map.Rules.Actors[name];
 
-				IPositionable positionable = null;
 				var resolveOrdersList = new List<IResolveOrder>();
 				var renderModifiersList = new List<IRenderModifier>();
 				var rendersList = new List<IRender>();
@@ -153,6 +160,7 @@ namespace OpenRA
 				var targetablesList = new List<ITargetable>();
 				var targetablePositionsList = new List<ITargetablePositions>();
 				var syncHashesList = new List<SyncHash>();
+				var crushablesList = new List<ICrushable>();
 
 				foreach (var traitInfo in Info.TraitsInConstructOrder())
 				{
@@ -164,7 +172,6 @@ namespace OpenRA
 					// performance-sensitive parts of the core game engine, such as pathfinding, visibility and rendering.
 					// Note: The blocks are required to limit the scope of the t's, so we make an exception to our normal style
 					// rules for spacing in order to keep these assignments compact and readable.
-					{ if (trait is IPositionable t) positionable = t; }
 					{ if (trait is IOccupySpace t) OccupiesSpace = t; }
 					{ if (trait is IEffectiveOwner t) EffectiveOwner = t; }
 					{ if (trait is IFacing t) facing = t; }
@@ -180,6 +187,7 @@ namespace OpenRA
 					{ if (trait is ITargetable t) targetablesList.Add(t); }
 					{ if (trait is ITargetablePositions t) targetablePositionsList.Add(t); }
 					{ if (trait is ISync t) syncHashesList.Add(new SyncHash(t)); }
+					{ if (trait is ICrushable t) crushablesList.Add(t); }
 				}
 
 				resolveOrders = resolveOrdersList.ToArray();
@@ -191,10 +199,10 @@ namespace OpenRA
 				tickIdles = tickIdlesList.ToArray();
 				Targetables = targetablesList.ToArray();
 				var targetablePositions = targetablePositionsList.ToArray();
-				enabledTargetablePositions = targetablePositions.Where(Exts.IsTraitEnabled);
+				EnabledTargetablePositions = targetablePositions.Where(Exts.IsTraitEnabled);
+				enabledTargetableWorldPositions = EnabledTargetablePositions.SelectMany(tp => tp.TargetablePositions(this));
 				SyncHashes = syncHashesList.ToArray();
-
-				setStaticTargetablePositions = positionable == null && targetablePositions.Any() && targetablePositions.All(tp => tp.AlwaysEnabled);
+				crushables = crushablesList.ToArray();
 			}
 		}
 
@@ -229,11 +237,6 @@ namespace OpenRA
 			foreach (var notify in allObserverNotifiers)
 				notify(this, readOnlyConditionCache);
 
-			// All actors that can move or teleport should have IPositionable, if not it's pretty safe to assume the actor is completely immobile and
-			// all targetable positions can be cached if all ITargetablePositions have no conditional requirements.
-			if (setStaticTargetablePositions)
-				staticTargetablePositions = enabledTargetablePositions.SelectMany(tp => tp.TargetablePositions(this)).ToArray();
-
 			// TODO: Other traits may need initialization after being notified of initial condition state.
 
 			// TODO: A post condition initialization notification phase may allow queueing activities instead.
@@ -246,7 +249,7 @@ namespace OpenRA
 					continue;
 
 				if (creationActivity != null)
-					throw new InvalidOperationException("More than one enabled ICreationActivity trait: {0} and {1}".F(creationActivity.GetType().Name, ica.GetType().Name));
+					throw new InvalidOperationException($"More than one enabled ICreationActivity trait: {creationActivity.GetType().Name} and {ica.GetType().Name}");
 
 				var activity = ica.GetCreationActivity();
 				if (activity == null)
@@ -365,8 +368,7 @@ namespace OpenRA
 
 		public override bool Equals(object obj)
 		{
-			var o = obj as Actor;
-			return o != null && Equals(o);
+			return obj is Actor o && Equals(o);
 		}
 
 		public bool Equals(Actor other)
@@ -487,7 +489,7 @@ namespace OpenRA
 			health.InflictDamage(this, attacker, damage, false);
 		}
 
-		public void Kill(Actor attacker, BitSet<DamageType> damageTypes = default(BitSet<DamageType>))
+		public void Kill(Actor attacker, BitSet<DamageType> damageTypes = default)
 		{
 			if (Disposed || health == null)
 				return;
@@ -528,7 +530,7 @@ namespace OpenRA
 		{
 			// PERF: Avoid LINQ.
 			foreach (var targetable in Targetables)
-				if (targetable.IsTraitEnabled() && targetable.TargetableBy(this, byActor))
+				if (targetable.TargetableBy(this, byActor))
 					return true;
 
 			return false;
@@ -536,11 +538,8 @@ namespace OpenRA
 
 		public IEnumerable<WPos> GetTargetablePositions()
 		{
-			if (staticTargetablePositions != null)
-				return staticTargetablePositions;
-
-			if (enabledTargetablePositions.Any())
-				return enabledTargetablePositions.SelectMany(tp => tp.TargetablePositions(this));
+			if (EnabledTargetablePositions.Any())
+				return enabledTargetableWorldPositions;
 
 			return new[] { CenterPosition };
 		}
@@ -549,7 +548,7 @@ namespace OpenRA
 
 		void UpdateConditionState(string condition, int token, bool isRevoke)
 		{
-			ConditionState conditionState = conditionStates.GetOrAdd(condition);
+			var conditionState = conditionStates.GetOrAdd(condition);
 
 			if (isRevoke)
 				conditionState.Tokens.Remove(token);
@@ -589,14 +588,14 @@ namespace OpenRA
 		public int RevokeCondition(int token)
 		{
 			if (!conditionTokens.TryGetValue(token, out var condition))
-				throw new InvalidOperationException("Attempting to revoke condition with invalid token {0} for {1}.".F(token, this));
+				throw new InvalidOperationException($"Attempting to revoke condition with invalid token {token} for {this}.");
 
 			conditionTokens.Remove(token);
 			UpdateConditionState(condition, token, true);
 			return InvalidConditionToken;
 		}
 
-		/// <summary>Returns whether the specified token is valid for RevokeCondition</summary>
+		/// <summary>Returns whether the specified token is valid for RevokeCondition.</summary>
 		public bool TokenValid(int token)
 		{
 			return conditionTokens.ContainsKey(token);
@@ -609,14 +608,13 @@ namespace OpenRA
 		Lazy<ScriptActorInterface> luaInterface;
 		public void OnScriptBind(ScriptContext context)
 		{
-			if (luaInterface == null)
-				luaInterface = Exts.Lazy(() => new ScriptActorInterface(context, this));
+			luaInterface ??= Exts.Lazy(() => new ScriptActorInterface(context, this));
 		}
 
 		public LuaValue this[LuaRuntime runtime, LuaValue keyValue]
 		{
-			get { return luaInterface.Value[runtime, keyValue]; }
-			set { luaInterface.Value[runtime, keyValue] = value; }
+			get => luaInterface.Value[runtime, keyValue];
+			set => luaInterface.Value[runtime, keyValue] = value;
 		}
 
 		public LuaValue Equals(LuaRuntime runtime, LuaValue left, LuaValue right)
@@ -629,7 +627,7 @@ namespace OpenRA
 
 		public LuaValue ToString(LuaRuntime runtime)
 		{
-			return "Actor ({0})".F(this);
+			return $"Actor ({this})";
 		}
 
 		public bool HasScriptProperty(string name)

OpenRA.Game/CPos.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -16,7 +16,7 @@ using OpenRA.Scripting;
 
 namespace OpenRA
 {
-	public struct CPos : IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaEqualityBinding, ILuaTableBinding, IEquatable<CPos>
+	public readonly struct CPos : IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaEqualityBinding, ILuaTableBinding, IEquatable<CPos>
 	{
 		// Coordinates are packed in a 32 bit signed int
 		// X and Y are 12 bits (signed): -2048...2047
@@ -25,13 +25,13 @@ namespace OpenRA
 		public readonly int Bits;
 
 		// X is padded to MSB, so bit shift does the correct sign extension
-		public int X { get { return Bits >> 20; } }
+		public int X => Bits >> 20;
 
 		// Align Y with a short, cast, then shift the rest of the way
 		// The signed short bit shift does the correct sign extension
-		public int Y { get { return ((short)(Bits >> 4)) >> 4; } }
+		public int Y => ((short)(Bits >> 4)) >> 4;
 
-		public byte Layer { get { return (byte)Bits; } }
+		public byte Layer => (byte)Bits;
 
 		public CPos(int bits) { Bits = bits; }
 		public CPos(int x, int y)
@@ -41,7 +41,7 @@ namespace OpenRA
 			Bits = (x & 0xFFF) << 20 | (y & 0xFFF) << 8 | layer;
 		}
 
-		public static readonly CPos Zero = new CPos(0, 0, 0);
+		public static readonly CPos Zero = new(0, 0, 0);
 
 		public static explicit operator CPos(int2 a) { return new CPos(a.X, a.Y); }
 
@@ -56,9 +56,15 @@ namespace OpenRA
 		public override int GetHashCode() { return Bits.GetHashCode(); }
 
 		public bool Equals(CPos other) { return Bits == other.Bits; }
-		public override bool Equals(object obj) { return obj is CPos && Equals((CPos)obj); }
+		public override bool Equals(object obj) { return obj is CPos cell && Equals(cell); }
 
-		public override string ToString() { return X + "," + Y; }
+		public override string ToString()
+		{
+			if (Layer == 0)
+				return X + "," + Y;
+
+			return X + "," + Y + "," + Layer;
+		}
 
 		public MPos ToMPos(Map map)
 		{
@@ -90,7 +96,7 @@ namespace OpenRA
 		public LuaValue Add(LuaRuntime runtime, LuaValue left, LuaValue right)
 		{
 			if (!left.TryGetClrValue(out CPos a) || !right.TryGetClrValue(out CVec b))
-				throw new LuaException("Attempted to call CPos.Add(CPos, CVec) with invalid arguments ({0}, {1})".F(left.WrappedClrType().Name, right.WrappedClrType().Name));
+				throw new LuaException($"Attempted to call CPos.Add(CPos, CVec) with invalid arguments ({left.WrappedClrType().Name}, {right.WrappedClrType().Name})");
 
 			return new LuaCustomClrObject(a + b);
 		}
@@ -99,7 +105,7 @@ namespace OpenRA
 		{
 			var rightType = right.WrappedClrType();
 			if (!left.TryGetClrValue(out CPos a))
-				throw new LuaException("Attempted to call CPos.Subtract(CPos, (CPos|CVec)) with invalid arguments ({0}, {1})".F(left.WrappedClrType().Name, rightType.Name));
+				throw new LuaException($"Attempted to call CPos.Subtract(CPos, (CPos|CVec)) with invalid arguments ({left.WrappedClrType().Name}, {rightType.Name})");
 
 			if (rightType == typeof(CPos))
 			{
@@ -112,7 +118,7 @@ namespace OpenRA
 				return new LuaCustomClrObject(a - b);
 			}
 
-			throw new LuaException("Attempted to call CPos.Subtract(CPos, (CPos|CVec)) with invalid arguments ({0}, {1})".F(left.WrappedClrType().Name, rightType.Name));
+			throw new LuaException($"Attempted to call CPos.Subtract(CPos, (CPos|CVec)) with invalid arguments ({left.WrappedClrType().Name}, {rightType.Name})");
 		}
 
 		public LuaValue Equals(LuaRuntime runtime, LuaValue left, LuaValue right)
@@ -132,14 +138,11 @@ namespace OpenRA
 					case "X": return X;
 					case "Y": return Y;
 					case "Layer": return Layer;
-					default: throw new LuaException("CPos does not define a member '{0}'".F(key));
+					default: throw new LuaException($"CPos does not define a member '{key}'");
 				}
 			}
 
-			set
-			{
-				throw new LuaException("CPos is read-only. Use CPos.New to create a new value");
-			}
+			set => throw new LuaException("CPos is read-only. Use CPos.New to create a new value");
 		}
 
 		#endregion

OpenRA.Game/CVec.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -17,12 +17,12 @@ using OpenRA.Scripting;
 
 namespace OpenRA
 {
-	public struct CVec : IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaUnaryMinusBinding, ILuaEqualityBinding, ILuaTableBinding, IEquatable<CVec>
+	public readonly struct CVec : IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaUnaryMinusBinding, ILuaEqualityBinding, ILuaTableBinding, IEquatable<CVec>
 	{
 		public readonly int X, Y;
 
 		public CVec(int x, int y) { X = x; Y = y; }
-		public static readonly CVec Zero = new CVec(0, 0);
+		public static readonly CVec Zero = new(0, 0);
 
 		public static CVec operator +(CVec a, CVec b) { return new CVec(a.X + b.X, a.Y + b.Y); }
 		public static CVec operator -(CVec a, CVec b) { return new CVec(a.X - b.X, a.Y - b.Y); }
@@ -42,8 +42,8 @@ namespace OpenRA
 
 		public CVec Sign() { return new CVec(Math.Sign(X), Math.Sign(Y)); }
 		public CVec Abs() { return new CVec(Math.Abs(X), Math.Abs(Y)); }
-		public int LengthSquared { get { return X * X + Y * Y; } }
-		public int Length { get { return Exts.ISqrt(LengthSquared); } }
+		public int LengthSquared => X * X + Y * Y;
+		public int Length => Exts.ISqrt(LengthSquared);
 
 		public CVec Clamp(Rectangle r)
 		{
@@ -55,20 +55,20 @@ namespace OpenRA
 		public override int GetHashCode() { return X.GetHashCode() ^ Y.GetHashCode(); }
 
 		public bool Equals(CVec other) { return other == this; }
-		public override bool Equals(object obj) { return obj is CVec && Equals((CVec)obj); }
+		public override bool Equals(object obj) { return obj is CVec vec && Equals(vec); }
 
 		public override string ToString() { return X + "," + Y; }
 
 		public static readonly CVec[] Directions =
 		{
-			new CVec(-1, -1),
-			new CVec(-1,  0),
-			new CVec(-1,  1),
-			new CVec(0, -1),
-			new CVec(0,  1),
-			new CVec(1, -1),
-			new CVec(1,  0),
-			new CVec(1,  1),
+			new(-1, -1),
+			new(-1,  0),
+			new(-1,  1),
+			new(0, -1),
+			new(0,  1),
+			new(1, -1),
+			new(1,  0),
+			new(1,  1),
 		};
 
 		#region Scripting interface
@@ -76,7 +76,7 @@ namespace OpenRA
 		public LuaValue Add(LuaRuntime runtime, LuaValue left, LuaValue right)
 		{
 			if (!left.TryGetClrValue(out CVec a) || !right.TryGetClrValue(out CVec b))
-				throw new LuaException("Attempted to call CVec.Add(CVec, CVec) with invalid arguments ({0}, {1})".F(left.WrappedClrType().Name, right.WrappedClrType().Name));
+				throw new LuaException($"Attempted to call CVec.Add(CVec, CVec) with invalid arguments ({left.WrappedClrType().Name}, {right.WrappedClrType().Name})");
 
 			return new LuaCustomClrObject(a + b);
 		}
@@ -84,7 +84,7 @@ namespace OpenRA
 		public LuaValue Subtract(LuaRuntime runtime, LuaValue left, LuaValue right)
 		{
 			if (!left.TryGetClrValue(out CVec a) || !right.TryGetClrValue(out CVec b))
-				throw new LuaException("Attempted to call CVec.Subtract(CVec, CVec) with invalid arguments ({0}, {1})".F(left.WrappedClrType().Name, right.WrappedClrType().Name));
+				throw new LuaException($"Attempted to call CVec.Subtract(CVec, CVec) with invalid arguments ({left.WrappedClrType().Name}, {right.WrappedClrType().Name})");
 
 			return new LuaCustomClrObject(a - b);
 		}
@@ -110,14 +110,11 @@ namespace OpenRA
 				{
 					case "X": return X;
 					case "Y": return Y;
-					default: throw new LuaException("CVec does not define a member '{0}'".F(key));
+					default: throw new LuaException($"CVec does not define a member '{key}'");
 				}
 			}
 
-			set
-			{
-				throw new LuaException("CVec is read-only. Use CVec.New to create a new value");
-			}
+			set => throw new LuaException("CVec is read-only. Use CVec.New to create a new value");
 		}
 
 		#endregion

OpenRA.Game/CryptoUtil.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,6 +22,9 @@ namespace OpenRA
 		// Fixed byte pattern for the OID header
 		static readonly byte[] OIDHeader = { 0x30, 0xD, 0x6, 0x9, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0xD, 0x1, 0x1, 0x1, 0x5, 0x0 };
 
+		static readonly char[] HexUpperAlphabet = "0123456789ABCDEF".ToArray();
+		static readonly char[] HexLowerAlphabet = "0123456789abcdef".ToArray();
+
 		public static string PublicKeyFingerprint(RSAParameters parameters)
 		{
 			// Public key fingerprint is defined as the SHA1 of the modulus + exponent bytes
@@ -53,33 +56,33 @@ namespace OpenRA
 				using (var s = new MemoryStream(data))
 				{
 					// SEQUENCE
-					s.ReadByte();
+					s.ReadUInt8();
 					ReadTLVLength(s);
 
 					// SEQUENCE -> fixed header junk
-					s.ReadByte();
+					s.ReadUInt8();
 					var headerLength = ReadTLVLength(s);
 					s.Position += headerLength;
 
 					// SEQUENCE -> BIT_STRING
-					s.ReadByte();
+					s.ReadUInt8();
 					ReadTLVLength(s);
-					s.ReadByte();
+					s.ReadUInt8();
 
 					// SEQUENCE -> BIT_STRING -> SEQUENCE
-					s.ReadByte();
+					s.ReadUInt8();
 					ReadTLVLength(s);
 
 					// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER (modulus)
-					s.ReadByte();
+					s.ReadUInt8();
 					var modulusLength = ReadTLVLength(s);
-					s.ReadByte();
+					s.ReadUInt8();
 					var modulus = s.ReadBytes(modulusLength - 1);
 
 					// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER (exponent)
-					s.ReadByte();
+					s.ReadUInt8();
 					var exponentLength = ReadTLVLength(s);
-					s.ReadByte();
+					s.ReadUInt8();
 					var exponent = s.ReadBytes(exponentLength - 1);
 
 					return new RSAParameters
@@ -158,13 +161,13 @@ namespace OpenRA
 
 		static int ReadTLVLength(Stream s)
 		{
-			var length = s.ReadByte();
+			var length = s.ReadUInt8();
 			if (length < 0x80)
 				return length;
 
-			var data = new byte[4];
-			s.ReadBytes(data, 0, Math.Min(length & 0x7F, 4));
-			return BitConverter.ToInt32(data.ToArray(), 0);
+			Span<byte> data = stackalloc byte[4];
+			s.ReadBytes(data[..Math.Min(length & 0x7F, 4)]);
+			return BitConverter.ToInt32(data);
 		}
 
 		static int TripletFullLength(int dataLength)
@@ -187,8 +190,10 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Log.Write("debug", "Failed to decrypt string with exception: {0}", e);
-				Console.WriteLine("String decryption failed: {0}", e);
+				Log.Write("debug", "Failed to decrypt string with exception:");
+				Log.Write("debug", e);
+				Console.WriteLine("String decryption failed:");
+				Console.WriteLine(e);
 				return null;
 			}
 		}
@@ -211,8 +216,10 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Log.Write("debug", "Failed to sign string with exception: {0}", e);
-				Console.WriteLine("String signing failed: {0}", e);
+				Log.Write("debug", "Failed to sign string with exception");
+				Log.Write("debug", e);
+				Console.WriteLine("String signing failed:");
+				Console.WriteLine(e);
 				return null;
 			}
 		}
@@ -235,27 +242,54 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Log.Write("debug", "Failed to verify signature with exception: {0}", e);
-				Console.WriteLine("Signature validation failed: {0}", e);
+				Log.Write("debug", "Failed to verify signature with exception:");
+				Log.Write("debug", e);
+				Console.WriteLine("Signature validation failed:");
+				Console.WriteLine(e);
 				return false;
 			}
 		}
 
 		public static string SHA1Hash(Stream data)
 		{
-			using (var csp = SHA1.Create())
-				return new string(csp.ComputeHash(data).SelectMany(a => a.ToString("x2")).ToArray());
+			using var csp = SHA1.Create();
+			return ToHex(csp.ComputeHash(data), true);
 		}
 
 		public static string SHA1Hash(byte[] data)
 		{
-			using (var csp = SHA1.Create())
-				return new string(csp.ComputeHash(data).SelectMany(a => a.ToString("x2")).ToArray());
+			using var csp = SHA1.Create();
+			return ToHex(csp.ComputeHash(data), true);
 		}
 
 		public static string SHA1Hash(string data)
 		{
 			return SHA1Hash(Encoding.UTF8.GetBytes(data));
 		}
+
+		public static string ToHex(ReadOnlySpan<byte> source, bool lowerCase = false)
+		{
+			if (source.Length == 0)
+				return string.Empty;
+
+			// excessively avoid stack overflow if source is too large (considering that we're allocating a new string)
+			var buffer = source.Length <= 256 ? stackalloc char[source.Length * 2] : new char[source.Length * 2];
+			return ToHexInternal(source, buffer, lowerCase);
+		}
+
+		static string ToHexInternal(ReadOnlySpan<byte> source, Span<char> buffer, bool lowerCase)
+		{
+			var sourceIndex = 0;
+			var alphabet = lowerCase ? HexLowerAlphabet : HexUpperAlphabet;
+
+			for (var i = 0; i < buffer.Length; i += 2)
+			{
+				var b = source[sourceIndex++];
+				buffer[i] = alphabet[b >> 4];
+				buffer[i + 1] = alphabet[b & 0xF];
+			}
+
+			return new string(buffer);
+		}
 	}
 }

OpenRA.Game/DefaultPlayer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,6 +15,6 @@ namespace OpenRA
 {
 	public class DefaultPlayer : IGlobalModData
 	{
-		public readonly Color Color = Color.FromAhsl(0, 0, 238);
+		public readonly Color Color = Color.FromArgb(0xEE, 0xEE, 0xEE);
 	}
 }

OpenRA.Game/Download.cs

@@ -1,96 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation, either version 3 of
- * the License, or (at your option) any later version. For more
- * information, see COPYING.
- */
-#endregion
-
-using System;
-using System.ComponentModel;
-using System.Net;
-
-namespace OpenRA
-{
-	public class Download
-	{
-		readonly object syncObject = new object();
-		WebClient wc;
-
-		public static string FormatErrorMessage(Exception e)
-		{
-			var ex = e as WebException;
-			if (ex == null)
-				return e.Message;
-
-			switch (ex.Status)
-			{
-				case WebExceptionStatus.RequestCanceled:
-					return "Cancelled";
-				case WebExceptionStatus.NameResolutionFailure:
-					return "DNS lookup failed";
-				case WebExceptionStatus.Timeout:
-					return "Connection timeout";
-				case WebExceptionStatus.ConnectFailure:
-					return "Cannot connect to remote server";
-				case WebExceptionStatus.ProtocolError:
-					return "File not found on remote server";
-				default:
-					return ex.Message;
-			}
-		}
-
-		void EnableTLS12OnWindows()
-		{
-			// Enable TLS 1.2 on Windows: .NET 4.7 on Windows 10 only supports obsolete protocols by default
-			// SecurityProtocolType.Tls12 is not defined in the .NET 4.5 reference dlls used by mono,
-			// so we must use the enum's constant value directly
-			if (Platform.CurrentPlatform == PlatformType.Windows)
-				ServicePointManager.SecurityProtocol |= (SecurityProtocolType)3072;
-		}
-
-		public Download(string url, string path, Action<DownloadProgressChangedEventArgs> onProgress, Action<AsyncCompletedEventArgs> onComplete)
-		{
-			EnableTLS12OnWindows();
-
-			lock (syncObject)
-			{
-				wc = new WebClient { Proxy = null };
-				wc.DownloadProgressChanged += (_, a) => onProgress(a);
-				wc.DownloadFileCompleted += (_, a) => { DisposeWebClient(); onComplete(a); };
-				wc.DownloadFileAsync(new Uri(url), path);
-			}
-		}
-
-		public Download(string url, Action<DownloadProgressChangedEventArgs> onProgress, Action<DownloadDataCompletedEventArgs> onComplete)
-		{
-			EnableTLS12OnWindows();
-
-			lock (syncObject)
-			{
-				wc = new WebClient { Proxy = null };
-				wc.DownloadProgressChanged += (_, a) => onProgress(a);
-				wc.DownloadDataCompleted += (_, a) => { DisposeWebClient(); onComplete(a); };
-				wc.DownloadDataAsync(new Uri(url));
-			}
-		}
-
-		void DisposeWebClient()
-		{
-			lock (syncObject)
-			{
-				wc.Dispose();
-				wc = null;
-			}
-		}
-
-		public void CancelAsync()
-		{
-			lock (syncObject)
-				wc?.CancelAsync();
-		}
-	}
-}

OpenRA.Game/Effects/AsyncAction.cs

@@ -1,39 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation, either version 3 of
- * the License, or (at your option) any later version. For more
- * information, see COPYING.
- */
-#endregion
-
-using System;
-using System.Collections.Generic;
-using OpenRA.Graphics;
-
-namespace OpenRA.Effects
-{
-	public class AsyncAction : IEffect
-	{
-		Action a;
-		IAsyncResult ar;
-
-		public AsyncAction(IAsyncResult ar, Action a)
-		{
-			this.a = a;
-			this.ar = ar;
-		}
-
-		public void Tick(World world)
-		{
-			if (ar.IsCompleted)
-			{
-				world.AddFrameEndTask(w => { w.Remove(this); a(); });
-			}
-		}
-
-		public IEnumerable<IRenderable> Render(WorldRenderer r) { yield break; }
-	}
-}

OpenRA.Game/Effects/DelayedAction.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -17,7 +17,7 @@ namespace OpenRA.Effects
 {
 	public class DelayedAction : IEffect
 	{
-		Action a;
+		readonly Action a;
 		int delay;
 
 		public DelayedAction(int delay, Action a)

OpenRA.Game/Effects/DelayedImpact.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of

OpenRA.Game/Effects/IEffect.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of

OpenRA.Game/ExternalMods.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -41,7 +41,7 @@ namespace OpenRA
 
 	public class ExternalMods : IReadOnlyDictionary<string, ExternalMod>
 	{
-		readonly Dictionary<string, ExternalMod> mods = new Dictionary<string, ExternalMod>();
+		readonly Dictionary<string, ExternalMod> mods = new();
 		readonly SheetBuilder sheetBuilder;
 
 		Sheet CreateSheet()
@@ -66,12 +66,8 @@ namespace OpenRA
 			// Several types of support directory types are available, depending on
 			// how the player has installed and launched the game.
 			// Read registration metadata from all of them
-			var sources = Enum.GetValues(typeof(SupportDirType))
-				.Cast<SupportDirType>()
-				.Select(t => Platform.GetSupportDir(t))
-				.Distinct();
-
-			foreach (var source in sources)
+			var stringPool = new HashSet<string>(); // Reuse common strings in YAML
+			foreach (var source in GetSupportDirs(ModRegistration.User | ModRegistration.System))
 			{
 				var metadataPath = Path.Combine(source, "ModMetadata");
 				if (!Directory.Exists(metadataPath))
@@ -81,13 +77,13 @@ namespace OpenRA
 				{
 					try
 					{
-						var yaml = MiniYaml.FromStream(File.OpenRead(path), path).First().Value;
+						var yaml = MiniYaml.FromFile(path, stringPool: stringPool).First().Value;
 						LoadMod(yaml, path);
 					}
 					catch (Exception e)
 					{
-						Log.Write("debug", "Failed to parse mod metadata file '{0}'", path);
-						Log.Write("debug", e.ToString());
+						Log.Write("debug", $"Failed to parse mod metadata file '{path}'");
+						Log.Write("debug", e);
 					}
 				}
 			}
@@ -99,17 +95,17 @@ namespace OpenRA
 
 			if (sheetBuilder != null)
 			{
-				var iconNode = yaml.Nodes.FirstOrDefault(n => n.Key == "Icon");
+				var iconNode = yaml.NodeWithKeyOrDefault("Icon");
 				if (iconNode != null && !string.IsNullOrEmpty(iconNode.Value.Value))
 					using (var stream = new MemoryStream(Convert.FromBase64String(iconNode.Value.Value)))
 						mod.Icon = sheetBuilder.Add(new Png(stream));
 
-				var icon2xNode = yaml.Nodes.FirstOrDefault(n => n.Key == "Icon2x");
+				var icon2xNode = yaml.NodeWithKeyOrDefault("Icon2x");
 				if (icon2xNode != null && !string.IsNullOrEmpty(icon2xNode.Value.Value))
 					using (var stream = new MemoryStream(Convert.FromBase64String(icon2xNode.Value.Value)))
 						mod.Icon2x = sheetBuilder.Add(new Png(stream), 1f / 2);
 
-				var icon3xNode = yaml.Nodes.FirstOrDefault(n => n.Key == "Icon3x");
+				var icon3xNode = yaml.NodeWithKeyOrDefault("Icon3x");
 				if (icon3xNode != null && !string.IsNullOrEmpty(icon3xNode.Value.Value))
 					using (var stream = new MemoryStream(Convert.FromBase64String(icon3xNode.Value.Value)))
 						mod.Icon3x = sheetBuilder.Add(new Png(stream), 1f / 3);
@@ -127,7 +123,7 @@ namespace OpenRA
 				return;
 
 			var key = ExternalMod.MakeKey(mod);
-			var yaml = new MiniYamlNode("Registration", new MiniYaml("", new List<MiniYamlNode>()
+			var yaml = new MiniYamlNode("Registration", new MiniYaml("", new[]
 			{
 				new MiniYamlNode("Id", mod.Id),
 				new MiniYamlNode("Version", mod.Metadata.Version),
@@ -136,19 +132,23 @@ namespace OpenRA
 				new MiniYamlNode("LaunchArgs", new[] { "Game.Mod=" + mod.Id }.Concat(launchArgs).JoinWith(", "))
 			}));
 
+			var iconNodes = new List<MiniYamlNode>();
+
 			using (var stream = mod.Package.GetStream("icon.png"))
 				if (stream != null)
-					yaml.Value.Nodes.Add(new MiniYamlNode("Icon", Convert.ToBase64String(stream.ReadAllBytes())));
+					iconNodes.Add(new MiniYamlNode("Icon", Convert.ToBase64String(stream.ReadAllBytes())));
 
 			using (var stream = mod.Package.GetStream("icon-2x.png"))
 				if (stream != null)
-					yaml.Value.Nodes.Add(new MiniYamlNode("Icon2x", Convert.ToBase64String(stream.ReadAllBytes())));
+					iconNodes.Add(new MiniYamlNode("Icon2x", Convert.ToBase64String(stream.ReadAllBytes())));
 
 			using (var stream = mod.Package.GetStream("icon-3x.png"))
 				if (stream != null)
-					yaml.Value.Nodes.Add(new MiniYamlNode("Icon3x", Convert.ToBase64String(stream.ReadAllBytes())));
+					iconNodes.Add(new MiniYamlNode("Icon3x", Convert.ToBase64String(stream.ReadAllBytes())));
 
-			var sources = new List<string>();
+			yaml = yaml.WithValue(yaml.Value.WithNodesAppended(iconNodes));
+
+			var sources = new HashSet<string>();
 			if (registration.HasFlag(ModRegistration.System))
 				sources.Add(Platform.GetSupportDir(SupportDirType.System));
 
@@ -167,7 +167,7 @@ namespace OpenRA
 			LoadMod(yaml.Value, forceRegistration: true);
 
 			var lines = new List<MiniYamlNode> { yaml }.ToLines().ToArray();
-			foreach (var source in sources.Distinct())
+			foreach (var source in sources)
 			{
 				var metadataPath = Path.Combine(source, "ModMetadata");
 
@@ -179,35 +179,23 @@ namespace OpenRA
 				catch (Exception e)
 				{
 					Log.Write("debug", "Failed to register current mod metadata");
-					Log.Write("debug", e.ToString());
+					Log.Write("debug", e);
 				}
 			}
 		}
 
 		/// <summary>
 		/// Removes invalid mod registrations:
-		/// * LaunchPath no longer exists
-		/// * LaunchPath and mod id matches the active mod, but the version is different
-		/// * Filename doesn't match internal key
-		/// * Fails to parse as a mod registration
+		/// <list type="bullet">
+		/// <item>LaunchPath no longer exists.</item>
+		/// <item>LaunchPath and mod id matches the active mod, but the version is different.</item>
+		/// <item>Filename doesn't match internal key.</item>
+		/// <item>Fails to parse as a mod registration.</item>
+		/// </list>
 		/// </summary>
-		internal void ClearInvalidRegistrations(ExternalMod activeMod, ModRegistration registration)
+		internal void ClearInvalidRegistrations(ModRegistration registration)
 		{
-			var sources = new List<string>();
-			if (registration.HasFlag(ModRegistration.System))
-				sources.Add(Platform.GetSupportDir(SupportDirType.System));
-
-			if (registration.HasFlag(ModRegistration.User))
-			{
-				// User support dir may be using the modern or legacy value, or overridden by the user
-				// Add all the possibilities and let the .Distinct() below ignore the duplicates
-				sources.Add(Platform.GetSupportDir(SupportDirType.User));
-				sources.Add(Platform.GetSupportDir(SupportDirType.ModernUser));
-				sources.Add(Platform.GetSupportDir(SupportDirType.LegacyUser));
-			}
-
-			var activeModKey = ExternalMod.MakeKey(activeMod);
-			foreach (var source in sources.Distinct())
+			foreach (var source in GetSupportDirs(registration))
 			{
 				var metadataPath = Path.Combine(source, "ModMetadata");
 				if (!Directory.Exists(metadataPath))
@@ -218,23 +206,20 @@ namespace OpenRA
 					string modKey = null;
 					try
 					{
-						var yaml = MiniYaml.FromStream(File.OpenRead(path), path).First().Value;
+						var yaml = MiniYaml.FromFile(path).First().Value;
 						var m = FieldLoader.Load<ExternalMod>(yaml);
 						modKey = ExternalMod.MakeKey(m);
 
-						// Continue to the next entry if it is the active mod (even if the LaunchPath is bogus)
-						if (modKey == activeModKey)
-							continue;
-
 						// Continue to the next entry if this one is valid
-						if (File.Exists(m.LaunchPath) && Path.GetFileNameWithoutExtension(path) == modKey &&
-							!(activeMod != null && m.LaunchPath == activeMod.LaunchPath && m.Id == activeMod.Id && m.Version != activeMod.Version))
+						// HACK: Explicitly invalidate paths to OpenRA.dll to clean up bogus metadata files
+						// that were created after the initial migration from .NET Framework to Core/5.
+						if (File.Exists(m.LaunchPath) && Path.GetFileNameWithoutExtension(path) == modKey && Path.GetExtension(m.LaunchPath) != ".dll")
 							continue;
 					}
 					catch (Exception e)
 					{
-						Log.Write("debug", "Failed to parse mod metadata file '{0}'", path);
-						Log.Write("debug", e.ToString());
+						Log.Write("debug", $"Failed to parse mod metadata file '{path}'");
+						Log.Write("debug", e);
 					}
 
 					// Remove from the ingame mod switcher
@@ -245,12 +230,12 @@ namespace OpenRA
 					try
 					{
 						File.Delete(path);
-						Log.Write("debug", "Removed invalid mod metadata file '{0}'", path);
+						Log.Write("debug", $"Removed invalid mod metadata file '{path}'");
 					}
 					catch (Exception e)
 					{
-						Log.Write("debug", "Failed to remove mod metadata file '{0}'", path);
-						Log.Write("debug", e.ToString());
+						Log.Write("debug", $"Failed to remove mod metadata file '{path}'");
+						Log.Write("debug", e);
 					}
 				}
 			}
@@ -258,23 +243,10 @@ namespace OpenRA
 
 		internal void Unregister(Manifest mod, ModRegistration registration)
 		{
-			var sources = new List<string>();
-			if (registration.HasFlag(ModRegistration.System))
-				sources.Add(Platform.GetSupportDir(SupportDirType.System));
-
-			if (registration.HasFlag(ModRegistration.User))
-			{
-				// User support dir may be using the modern or legacy value, or overridden by the user
-				// Add all the possibilities and let the .Distinct() below ignore the duplicates
-				sources.Add(Platform.GetSupportDir(SupportDirType.User));
-				sources.Add(Platform.GetSupportDir(SupportDirType.ModernUser));
-				sources.Add(Platform.GetSupportDir(SupportDirType.LegacyUser));
-			}
-
 			var key = ExternalMod.MakeKey(mod);
 			mods.Remove(key);
 
-			foreach (var source in sources.Distinct())
+			foreach (var source in GetSupportDirs(registration))
 			{
 				var path = Path.Combine(source, "ModMetadata", key + ".yaml");
 				try
@@ -284,16 +256,39 @@ namespace OpenRA
 				}
 				catch (Exception e)
 				{
-					Log.Write("debug", "Failed to remove mod metadata file '{0}'", path);
-					Log.Write("debug", e.ToString());
+					Log.Write("debug", $"Failed to remove mod metadata file '{path}'");
+					Log.Write("debug", e);
 				}
 			}
 		}
 
-		public ExternalMod this[string key] { get { return mods[key]; } }
-		public int Count { get { return mods.Count; } }
-		public ICollection<string> Keys { get { return mods.Keys; } }
-		public ICollection<ExternalMod> Values { get { return mods.Values; } }
+		static IEnumerable<string> GetSupportDirs(ModRegistration registration)
+		{
+			var sources = new HashSet<string>(4);
+			if (registration.HasFlag(ModRegistration.System))
+				sources.Add(Platform.GetSupportDir(SupportDirType.System));
+
+			if (registration.HasFlag(ModRegistration.User))
+			{
+				// User support dir may be using the modern or legacy value, or overridden by the user
+				// Add all the possibilities and let the HashSet ignore the duplicates
+				sources.Add(Platform.GetSupportDir(SupportDirType.User));
+				sources.Add(Platform.GetSupportDir(SupportDirType.ModernUser));
+				sources.Add(Platform.GetSupportDir(SupportDirType.LegacyUser));
+			}
+
+			return sources;
+		}
+
+		public ExternalMod this[string key] => mods[key];
+		public int Count => mods.Count;
+		public ICollection<string> Keys => mods.Keys;
+		public ICollection<ExternalMod> Values => mods.Values;
+
+		IEnumerable<string> IReadOnlyDictionary<string, ExternalMod>.Keys => ((IReadOnlyDictionary<string, ExternalMod>)mods).Keys;
+
+		IEnumerable<ExternalMod> IReadOnlyDictionary<string, ExternalMod>.Values => ((IReadOnlyDictionary<string, ExternalMod>)mods).Values;
+
 		public bool ContainsKey(string key) { return mods.ContainsKey(key); }
 		public IEnumerator<KeyValuePair<string, ExternalMod>> GetEnumerator() { return mods.GetEnumerator(); }
 		public bool TryGetValue(string key, out ExternalMod value) { return mods.TryGetValue(key, out value); }

OpenRA.Game/Exts.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,26 +22,14 @@ namespace OpenRA
 {
 	public static class Exts
 	{
-		public static bool IsUppercase(this string str)
+		public static string FormatInvariant(this string format, params object[] args)
 		{
-			return string.Compare(str.ToUpperInvariant(), str, false) == 0;
+			return string.Format(CultureInfo.InvariantCulture, format, args);
 		}
 
-		public static string F(this string fmt, params object[] args)
+		public static string FormatCurrent(this string format, params object[] args)
 		{
-			return string.Format(fmt, args);
-		}
-
-		public static T WithDefault<T>(T def, Func<T> f)
-		{
-			try { return f(); }
-			catch { return def; }
-		}
-
-		public static void Do<T>(this IEnumerable<T> e, Action<T> fn)
-		{
-			foreach (var ee in e)
-				fn(ee);
+			return string.Format(CultureInfo.CurrentCulture, format, args);
 		}
 
 		public static Lazy<T> Lazy<T>(Func<T> p) { return new Lazy<T>(p); }
@@ -51,21 +39,16 @@ namespace OpenRA
 			return a.GetTypes().Select(t => t.Namespace).Distinct().Where(n => n != null);
 		}
 
-		public static bool HasAttribute<T>(this MemberInfo mi)
+		public static bool HasAttribute<TAttribute>(this MemberInfo mi)
+			where TAttribute : Attribute
 		{
-			return mi.GetCustomAttributes(typeof(T), true).Length != 0;
+			return Attribute.IsDefined(mi, typeof(TAttribute));
 		}
 
-		public static T[] GetCustomAttributes<T>(this MemberInfo mi, bool inherit)
-			where T : class
+		public static TAttribute[] GetCustomAttributes<TAttribute>(this MemberInfo mi, bool inherit)
+			where TAttribute : Attribute
 		{
-			return (T[])mi.GetCustomAttributes(typeof(T), inherit);
-		}
-
-		public static T[] GetCustomAttributes<T>(this ParameterInfo mi)
-			where T : class
-		{
-			return (T[])mi.GetCustomAttributes(typeof(T), true);
+			return (TAttribute[])mi.GetCustomAttributes(typeof(TAttribute), inherit);
 		}
 
 		public static T Clamp<T>(this T val, T min, T max) where T : IComparable<T>
@@ -107,7 +90,7 @@ namespace OpenRA
 			//  - the triangles ACD and BCD must have opposite sense (clockwise or anticlockwise)
 			//  - the triangles CAB and DAB must have opposite sense
 			// Segments intersect if the orientation (clockwise or anticlockwise) of the two points in each line segment are opposite with respect to the other
-			// Assumes that lines are not colinear
+			// Assumes that lines are not collinear
 			return WindingDirectionTest(c, d, a) != WindingDirectionTest(c, d, b) && WindingDirectionTest(a, b, c) != WindingDirectionTest(a, b, d);
 		}
 
@@ -125,23 +108,57 @@ namespace OpenRA
 
 		public static V GetOrAdd<K, V>(this Dictionary<K, V> d, K k, V v)
 		{
+#if NET5_0_OR_GREATER
+			// SAFETY: Dictionary cannot be modified whilst the ref is alive.
+			ref var value = ref System.Runtime.InteropServices.CollectionsMarshal.GetValueRefOrAddDefault(d, k, out var exists);
+			if (!exists)
+				value = v;
+			return value;
+#else
 			if (!d.TryGetValue(k, out var ret))
 				d.Add(k, ret = v);
 			return ret;
+#endif
 		}
 
 		public static V GetOrAdd<K, V>(this Dictionary<K, V> d, K k, Func<K, V> createFn)
 		{
+			// Cannot use CollectionsMarshal.GetValueRefOrAddDefault here,
+			// the creation function could mutate the dictionary which would invalidate the ref.
 			if (!d.TryGetValue(k, out var ret))
 				d.Add(k, ret = createFn(k));
 			return ret;
 		}
 
+		public static T GetOrAdd<T>(this HashSet<T> set, T value)
+		{
+			if (!set.TryGetValue(value, out var ret))
+				set.Add(ret = value);
+			return ret;
+		}
+
+		public static T GetOrAdd<T>(this HashSet<T> set, T value, Func<T, T> createFn)
+		{
+			if (!set.TryGetValue(value, out var ret))
+				set.Add(ret = createFn(value));
+			return ret;
+		}
+
 		public static int IndexOf<T>(this T[] array, T value)
 		{
 			return Array.IndexOf(array, value);
 		}
 
+		public static T FirstOrDefault<T>(this T[] array, Predicate<T> match)
+		{
+			return Array.Find(array, match);
+		}
+
+		public static T FirstOrDefault<T>(this List<T> list, Predicate<T> match)
+		{
+			return list.Find(match);
+		}
+
 		public static T Random<T>(this IEnumerable<T> ts, MersenneTwister r)
 		{
 			return Random(ts, r, true);
@@ -154,14 +171,14 @@ namespace OpenRA
 
 		static T Random<T>(IEnumerable<T> ts, MersenneTwister r, bool throws)
 		{
-			var xs = ts as ICollection<T>;
-			xs = xs ?? ts.ToList();
+			var xs = ts as IReadOnlyCollection<T>;
+			xs ??= ts.ToList();
 			if (xs.Count == 0)
 			{
 				if (throws)
-					throw new ArgumentException("Collection must not be empty.", "ts");
+					throw new ArgumentException("Collection must not be empty.", nameof(ts));
 				else
-					return default(T);
+					return default;
 			}
 			else
 				return xs.ElementAt(r.Next(xs.Count));
@@ -236,9 +253,9 @@ namespace OpenRA
 			{
 				if (!e.MoveNext())
 					if (throws)
-						throw new ArgumentException("Collection must not be empty.", "ts");
+						throw new ArgumentException("Collection must not be empty.", nameof(ts));
 					else
-						return default(T);
+						return default;
 				t = e.Current;
 				u = selector(t);
 				while (e.MoveNext())
@@ -278,7 +295,7 @@ namespace OpenRA
 		public static int ISqrt(int number, ISqrtRoundMode round = ISqrtRoundMode.Floor)
 		{
 			if (number < 0)
-				throw new InvalidOperationException("Attempted to calculate the square root of a negative integer: {0}".F(number));
+				throw new InvalidOperationException($"Attempted to calculate the square root of a negative integer: {number}");
 
 			return (int)ISqrt((uint)number, round);
 		}
@@ -309,9 +326,9 @@ namespace OpenRA
 
 			// Adjust for other rounding modes
 			if (round == ISqrtRoundMode.Nearest && remainder > root)
-				root += 1;
+				root++;
 			else if (round == ISqrtRoundMode.Ceiling && root * root < number)
-				root += 1;
+				root++;
 
 			return root;
 		}
@@ -319,7 +336,7 @@ namespace OpenRA
 		public static long ISqrt(long number, ISqrtRoundMode round = ISqrtRoundMode.Floor)
 		{
 			if (number < 0)
-				throw new InvalidOperationException("Attempted to calculate the square root of a negative integer: {0}".F(number));
+				throw new InvalidOperationException($"Attempted to calculate the square root of a negative integer: {number}");
 
 			return (long)ISqrt((ulong)number, round);
 		}
@@ -350,13 +367,23 @@ namespace OpenRA
 
 			// Adjust for other rounding modes
 			if (round == ISqrtRoundMode.Nearest && remainder > root)
-				root += 1;
+				root++;
 			else if (round == ISqrtRoundMode.Ceiling && root * root < number)
-				root += 1;
+				root++;
 
 			return root;
 		}
 
+		public static int MultiplyBySqrtTwo(short number)
+		{
+			return number * 46341 / 32768;
+		}
+
+		public static int MultiplyBySqrtTwoOverTwo(int number)
+		{
+			return (int)(number * 23170L / 32768L);
+		}
+
 		public static int IntegerDivisionRoundingAwayFromZero(int dividend, int divisor)
 		{
 			var quotient = Math.DivRem(dividend, divisor, out var remainder);
@@ -375,6 +402,11 @@ namespace OpenRA
 			return ts.Concat(moreTs);
 		}
 
+		public static IEnumerable<T> Exclude<T>(this IEnumerable<T> ts, params T[] exclusions)
+		{
+			return ts.Except(exclusions);
+		}
+
 		public static HashSet<T> ToHashSet<T>(this IEnumerable<T> source)
 		{
 			return new HashSet<T>(source);
@@ -392,12 +424,13 @@ namespace OpenRA
 			string debugName, Func<TKey, string> logKey = null, Func<TElement, string> logValue = null)
 		{
 			// Fall back on ToString() if null functions are provided:
-			logKey = logKey ?? (s => s.ToString());
-			logValue = logValue ?? (s => s.ToString());
+			logKey ??= s => s.ToString();
+			logValue ??= s => s.ToString();
 
 			// Try to build a dictionary and log all duplicates found (if any):
 			var dupKeys = new Dictionary<TKey, List<string>>();
-			var d = new Dictionary<TKey, TElement>();
+			var capacity = source is ICollection<TSource> collection ? collection.Count : 0;
+			var d = new Dictionary<TKey, TElement>(capacity);
 			foreach (var item in source)
 			{
 				var key = keySelector(item);
@@ -408,29 +441,28 @@ namespace OpenRA
 					continue;
 
 				// Check for a key conflict:
-				if (d.ContainsKey(key))
+				if (!d.TryAdd(key, element))
 				{
 					if (!dupKeys.TryGetValue(key, out var dupKeyMessages))
 					{
 						// Log the initial conflicting value already inserted:
-						dupKeyMessages = new List<string>();
-						dupKeyMessages.Add(logValue(d[key]));
+						dupKeyMessages = new List<string>
+						{
+							logValue(d[key])
+						};
 						dupKeys.Add(key, dupKeyMessages);
 					}
 
 					// Log this conflicting value:
 					dupKeyMessages.Add(logValue(element));
-					continue;
 				}
-
-				d.Add(key, element);
 			}
 
 			// If any duplicates were found, throw a descriptive error
 			if (dupKeys.Count > 0)
 			{
-				var badKeysFormatted = string.Join(", ", dupKeys.Select(p => "{0}: [{1}]".F(logKey(p.Key), string.Join(",", p.Value))));
-				var msg = "{0}, duplicate values found for the following keys: {1}".F(debugName, badKeysFormatted);
+				var badKeysFormatted = string.Join(", ", dupKeys.Select(p => $"{logKey(p.Key)}: [{string.Join(",", p.Value)}]"));
+				var msg = $"{debugName}, duplicate values found for the following keys: {badKeysFormatted}";
 				throw new ArgumentException(msg);
 			}
 
@@ -489,17 +521,22 @@ namespace OpenRA
 			return result;
 		}
 
-		public static int ParseIntegerInvariant(string s)
-		{
-			return int.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
-		}
-
-		public static byte ParseByte(string s)
+		public static byte ParseByteInvariant(string s)
 		{
 			return byte.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
 		}
 
-		public static bool TryParseIntegerInvariant(string s, out int i)
+		public static short ParseInt16Invariant(string s)
+		{
+			return short.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
+		}
+
+		public static int ParseInt32Invariant(string s)
+		{
+			return int.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
+		}
+
+		public static bool TryParseInt32Invariant(string s, out int i)
 		{
 			return int.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
 		}
@@ -509,10 +546,29 @@ namespace OpenRA
 			return long.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
 		}
 
+		public static string ToStringInvariant(this byte i)
+		{
+			return i.ToString(NumberFormatInfo.InvariantInfo);
+		}
+
+		public static string ToStringInvariant(this byte i, string format)
+		{
+			return i.ToString(format, NumberFormatInfo.InvariantInfo);
+		}
+
+		public static string ToStringInvariant(this int i)
+		{
+			return i.ToString(NumberFormatInfo.InvariantInfo);
+		}
+
+		public static string ToStringInvariant(this int i, string format)
+		{
+			return i.ToString(format, NumberFormatInfo.InvariantInfo);
+		}
+
 		public static bool IsTraitEnabled<T>(this T trait)
 		{
-			var disabledTrait = trait as IDisabledTrait;
-			return disabledTrait == null || !disabledTrait.IsTraitDisabled;
+			return trait is not IDisabledTrait disabledTrait || !disabledTrait.IsTraitDisabled;
 		}
 
 		public static T FirstEnabledTraitOrDefault<T>(this IEnumerable<T> ts)
@@ -522,7 +578,7 @@ namespace OpenRA
 				if (t.IsTraitEnabled())
 					return t;
 
-			return default(T);
+			return default;
 		}
 
 		public static T FirstEnabledTraitOrDefault<T>(this T[] ts)
@@ -532,8 +588,72 @@ namespace OpenRA
 				if (t.IsTraitEnabled())
 					return t;
 
-			return default(T);
+			return default;
 		}
+
+		public static T FirstEnabledConditionalTraitOrDefault<T>(this IEnumerable<T> ts) where T : IDisabledTrait
+		{
+			// PERF: Avoid LINQ.
+			foreach (var t in ts)
+				if (!t.IsTraitDisabled)
+					return t;
+
+			return default;
+		}
+
+		public static T FirstEnabledConditionalTraitOrDefault<T>(this T[] ts) where T : IDisabledTrait
+		{
+			// PERF: Avoid LINQ.
+			foreach (var t in ts)
+				if (!t.IsTraitDisabled)
+					return t;
+
+			return default;
+		}
+
+		public static LineSplitEnumerator SplitLines(this string str, char separator)
+		{
+			return new LineSplitEnumerator(str.AsSpan(), separator);
+		}
+	}
+
+	public ref struct LineSplitEnumerator
+	{
+		ReadOnlySpan<char> str;
+		readonly char separator;
+
+		public LineSplitEnumerator(ReadOnlySpan<char> str, char separator)
+		{
+			this.str = str;
+			this.separator = separator;
+			Current = default;
+		}
+
+		public readonly LineSplitEnumerator GetEnumerator() => this;
+
+		public bool MoveNext()
+		{
+			var span = str;
+
+			// Reach the end of the string
+			if (span.Length == 0)
+				return false;
+
+			var index = span.IndexOf(separator);
+			if (index == -1)
+			{
+				// The remaining string is an empty string
+				str = ReadOnlySpan<char>.Empty;
+				Current = span;
+				return true;
+			}
+
+			Current = span[..index];
+			str = span[(index + 1)..];
+			return true;
+		}
+
+		public ReadOnlySpan<char> Current { get; private set; }
 	}
 
 	public static class Enum<T>
@@ -549,7 +669,7 @@ namespace OpenRA
 
 			if (values.Any(x => !names.Contains(x)))
 			{
-				value = default(T);
+				value = default;
 				return false;
 			}
 

OpenRA.Game/FieldSaver.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,6 +15,7 @@ using System.ComponentModel;
 using System.Globalization;
 using System.Linq;
 using System.Reflection;
+using System.Text;
 using OpenRA.Primitives;
 
 namespace OpenRA
@@ -58,7 +59,7 @@ namespace OpenRA
 
 			return new MiniYaml(
 				null,
-				fields.Select(info => new MiniYamlNode(info.YamlName, FormatValue(o, info.Field))).ToList());
+				fields.Select(info => new MiniYamlNode(info.YamlName, FormatValue(o, info.Field))));
 		}
 
 		public static MiniYamlNode SaveField(object o, string field)
@@ -72,37 +73,19 @@ namespace OpenRA
 				return "";
 
 			var t = v.GetType();
-
-			if (t == typeof(Color))
-			{
-				return ((Color)v).ToString();
-			}
-
-			if (t == typeof(Rectangle))
-			{
-				var r = (Rectangle)v;
-				return "{0},{1},{2},{3}".F(r.X, r.Y, r.Width, r.Height);
-			}
-
 			if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(BitSet<>))
-			{
 				return ((IEnumerable<string>)v).Select(FormatValue).JoinWith(", ");
-			}
 
 			if (t.IsArray && t.GetArrayRank() == 1)
-			{
 				return ((Array)v).Cast<object>().Select(FormatValue).JoinWith(", ");
-			}
 
 			if (t.IsGenericType && (t.GetGenericTypeDefinition() == typeof(HashSet<>) || t.GetGenericTypeDefinition() == typeof(List<>)))
-			{
 				return ((System.Collections.IEnumerable)v).Cast<object>().Select(FormatValue).JoinWith(", ");
-			}
 
 			// This is only for documentation generation
 			if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Dictionary<,>))
 			{
-				var result = "";
+				var result = new StringBuilder();
 				var dict = (System.Collections.IDictionary)v;
 				foreach (var kvp in dict)
 				{
@@ -112,17 +95,14 @@ namespace OpenRA
 					var formattedKey = FormatValue(key);
 					var formattedValue = FormatValue(value);
 
-					result += "{0}: {1}{2}".F(formattedKey, formattedValue, Environment.NewLine);
+					result.Append($"{formattedKey}: {formattedValue}{Environment.NewLine}");
 				}
 
-				return result;
+				return result.ToString();
 			}
 
-			if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Primitives.Cache<,>))
-				return ""; // TODO
-
-			if (t == typeof(DateTime))
-				return ((DateTime)v).ToString("yyyy-MM-dd HH-mm-ss", CultureInfo.InvariantCulture);
+			if (v is DateTime d)
+				return d.ToString("yyyy-MM-dd HH-mm-ss", CultureInfo.InvariantCulture);
 
 			// Try the TypeConverter
 			var conv = TypeDescriptor.GetConverter(t);

OpenRA.Game/FileFormats/Png.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -16,7 +16,9 @@ using System.Linq;
 using System.Net;
 using System.Text;
 using ICSharpCode.SharpZipLib.Checksum;
+using ICSharpCode.SharpZipLib.Zip.Compression;
 using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
+using OpenRA.Graphics;
 using OpenRA.Primitives;
 
 namespace OpenRA.FileFormats
@@ -25,11 +27,14 @@ namespace OpenRA.FileFormats
 	{
 		static readonly byte[] Signature = { 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a };
 
-		public int Width { get; set; }
-		public int Height { get; set; }
-		public Color[] Palette { get; set; }
-		public byte[] Data { get; set; }
-		public Dictionary<string, string> EmbeddedData = new Dictionary<string, string>();
+		public int Width { get; }
+		public int Height { get; }
+		public Color[] Palette { get; }
+		public byte[] Data { get; }
+		public SpriteFrameType Type { get; }
+		public Dictionary<string, string> EmbeddedData = new();
+
+		public int PixelStride => Type == SpriteFrameType.Indexed8 ? 1 : Type == SpriteFrameType.Rgb24 ? 3 : 4;
 
 		public Png(Stream s)
 		{
@@ -38,16 +43,16 @@ namespace OpenRA.FileFormats
 
 			s.Position += 8;
 			var headerParsed = false;
-			var isPaletted = false;
-			var is24Bit = false;
 			var data = new List<byte>();
+			Type = SpriteFrameType.Rgba32;
 
+			byte bitDepth = 8;
 			while (true)
 			{
 				var length = IPAddress.NetworkToHostOrder(s.ReadInt32());
-				var type = Encoding.UTF8.GetString(s.ReadBytes(4));
+				var type = s.ReadASCII(4);
 				var content = s.ReadBytes(length);
-				/*var crc = */s.ReadInt32();
+				s.ReadInt32(); // crc
 
 				if (!headerParsed && type != "IHDR")
 					throw new InvalidDataException("Invalid PNG file - header does not appear first.");
@@ -63,20 +68,18 @@ namespace OpenRA.FileFormats
 							Width = IPAddress.NetworkToHostOrder(ms.ReadInt32());
 							Height = IPAddress.NetworkToHostOrder(ms.ReadInt32());
 
-							var bitDepth = ms.ReadUInt8();
-							var colorType = (PngColorType)ms.ReadByte();
-							isPaletted = IsPaletted(bitDepth, colorType);
-							is24Bit = colorType == PngColorType.Color;
+							bitDepth = ms.ReadUInt8();
+							var colorType = (PngColorType)ms.ReadUInt8();
+							if (IsPaletted(bitDepth, colorType))
+								Type = SpriteFrameType.Indexed8;
+							else if (colorType == PngColorType.Color)
+								Type = SpriteFrameType.Rgb24;
 
-							var dataLength = Width * Height;
-							if (!isPaletted)
-								dataLength *= 4;
+							Data = new byte[Width * Height * PixelStride];
 
-							Data = new byte[dataLength];
-
-							var compression = ms.ReadByte();
-							/*var filter = */ms.ReadByte();
-							var interlace = ms.ReadByte();
+							var compression = ms.ReadUInt8();
+							ms.ReadUInt8(); // filter
+							var interlace = ms.ReadUInt8();
 
 							if (compression != 0)
 								throw new InvalidDataException("Compression method not supported");
@@ -91,10 +94,10 @@ namespace OpenRA.FileFormats
 
 						case "PLTE":
 						{
-							Palette = new Color[256];
-							for (var i = 0; i < length / 3; i++)
+							Palette = new Color[length / 3];
+							for (var i = 0; i < Palette.Length; i++)
 							{
-								var r = ms.ReadByte(); var g = ms.ReadByte(); var b = ms.ReadByte();
+								var r = ms.ReadUInt8(); var g = ms.ReadUInt8(); var b = ms.ReadUInt8();
 								Palette[i] = Color.FromArgb(r, g, b);
 							}
 
@@ -107,7 +110,7 @@ namespace OpenRA.FileFormats
 								throw new InvalidDataException("Non-Palette indexed PNG are not supported.");
 
 							for (var i = 0; i < length; i++)
-								Palette[i] = Color.FromArgb(ms.ReadByte(), Palette[i]);
+								Palette[i] = Color.FromArgb(ms.ReadUInt8(), Palette[i]);
 
 							break;
 						}
@@ -133,39 +136,83 @@ namespace OpenRA.FileFormats
 							{
 								using (var ds = new InflaterInputStream(ns))
 								{
-									var pxStride = isPaletted ? 1 : is24Bit ? 3 : 4;
-									var srcStride = Width * pxStride;
-									var destStride = Width * (isPaletted ? 1 : 4);
+									var pxStride = PixelStride;
+									var rowStride = Width * pxStride;
+									var pixelsPerByte = 8 / bitDepth;
+									var sourceRowStride = Exts.IntegerDivisionRoundingAwayFromZero(rowStride, pixelsPerByte);
 
-									var prevLine = new byte[srcStride];
+									Span<byte> prevLine = new byte[rowStride];
 									for (var y = 0; y < Height; y++)
 									{
-										var filter = (PngFilter)ds.ReadByte();
-										var line = ds.ReadBytes(srcStride);
+										var filter = (PngFilter)ds.ReadUInt8();
+										ds.ReadBytes(Data, y * rowStride, sourceRowStride);
+										var line = Data.AsSpan(y * rowStride, rowStride);
 
-										for (var i = 0; i < srcStride; i++)
-											line[i] = i < pxStride
-												? UnapplyFilter(filter, line[i], 0, prevLine[i], 0)
-												: UnapplyFilter(filter, line[i], line[i - pxStride], prevLine[i], prevLine[i - pxStride]);
-
-										if (is24Bit)
+										// If the source has a bit depth of 1, 2 or 4 it packs multiple pixels per byte.
+										// Unpack to bit depth of 8, yielding 1 pixel per byte.
+										// This makes life easier for consumers of palleted data.
+										if (bitDepth < 8)
 										{
-											// Fold alpha channel into RGB data
-											for (var i = 0; i < line.Length / 3; i++)
+											var mask = 0xFF >> (8 - bitDepth);
+											for (var i = sourceRowStride - 1; i >= 0; i--)
 											{
-												Array.Copy(line, 3 * i, Data, y * destStride + 4 * i, 3);
-												Data[y * destStride + 4 * i + 3] = 255;
+												var packed = line[i];
+												for (var j = 0; j < pixelsPerByte; j++)
+												{
+													var dest = i * pixelsPerByte + j;
+													if (dest < line.Length) // Guard against last byte being only partially packed
+														line[dest] = (byte)(packed >> (8 - (j + 1) * bitDepth) & mask);
+												}
 											}
 										}
-										else
-											Array.Copy(line, 0, Data, y * destStride, line.Length);
+
+										switch (filter)
+										{
+											case PngFilter.None:
+												break;
+											case PngFilter.Sub:
+												for (var i = pxStride; i < rowStride; i++)
+													line[i] += line[i - pxStride];
+												break;
+											case PngFilter.Up:
+												for (var i = 0; i < rowStride; i++)
+													line[i] += prevLine[i];
+												break;
+											case PngFilter.Average:
+												for (var i = 0; i < pxStride; i++)
+													line[i] += Average(0, prevLine[i]);
+												for (var i = pxStride; i < rowStride; i++)
+													line[i] += Average(line[i - pxStride], prevLine[i]);
+												break;
+											case PngFilter.Paeth:
+												for (var i = 0; i < pxStride; i++)
+													line[i] += Paeth(0, prevLine[i], 0);
+												for (var i = pxStride; i < rowStride; i++)
+													line[i] += Paeth(line[i - pxStride], prevLine[i], prevLine[i - pxStride]);
+												break;
+											default:
+												throw new InvalidOperationException("Unsupported Filter");
+										}
 
 										prevLine = line;
 									}
+
+									static byte Average(byte a, byte b) => (byte)((a + b) / 2);
+
+									static byte Paeth(byte a, byte b, byte c)
+									{
+										var p = a + b - c;
+										var pa = Math.Abs(p - a);
+										var pb = Math.Abs(p - b);
+										var pc = Math.Abs(p - c);
+
+										return (pa <= pb && pa <= pc) ? a :
+											(pb <= pc) ? b : c;
+									}
 								}
 							}
 
-							if (isPaletted && Palette == null)
+							if (Type == SpriteFrameType.Indexed8 && Palette == null)
 								throw new InvalidDataException("Non-Palette indexed PNG are not supported.");
 
 							return;
@@ -175,7 +222,7 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-		public Png(byte[] data, int width, int height, Color[] palette = null,
+		public Png(byte[] data, SpriteFrameType type, int width, int height, Color[] palette = null,
 			Dictionary<string, string> embeddedData = null)
 		{
 			var expectLength = width * height;
@@ -185,11 +232,46 @@ namespace OpenRA.FileFormats
 			if (data.Length != expectLength)
 				throw new InvalidDataException("Input data does not match expected length");
 
+			Type = type;
 			Width = width;
 			Height = height;
 
-			Palette = palette;
-			Data = data;
+			switch (type)
+			{
+				case SpriteFrameType.Indexed8:
+				case SpriteFrameType.Rgba32:
+				case SpriteFrameType.Rgb24:
+				{
+					// Data is already in a compatible format
+					Data = data;
+					if (type == SpriteFrameType.Indexed8)
+						Palette = palette;
+
+					break;
+				}
+
+				case SpriteFrameType.Bgra32:
+				case SpriteFrameType.Bgr24:
+				{
+					// Convert to big endian
+					Data = new byte[data.Length];
+					var stride = PixelStride;
+					for (var i = 0; i < width * height; i++)
+					{
+						Data[stride * i] = data[stride * i + 2];
+						Data[stride * i + 1] = data[stride * i + 1];
+						Data[stride * i + 2] = data[stride * i + 0];
+
+						if (type == SpriteFrameType.Bgra32)
+							Data[stride * i + 3] = data[stride * i + 3];
+					}
+
+					break;
+				}
+
+				default:
+					throw new InvalidDataException($"Unhandled SpriteFrameType {type}");
+			}
 
 			if (embeddedData != null)
 				EmbeddedData = embeddedData;
@@ -203,38 +285,13 @@ namespace OpenRA.FileFormats
 			return isPng;
 		}
 
-		static byte UnapplyFilter(PngFilter f, byte x, byte a, byte b, byte c)
-		{
-			switch (f)
-			{
-				case PngFilter.None: return x;
-				case PngFilter.Sub: return (byte)(x + a);
-				case PngFilter.Up: return (byte)(x + b);
-				case PngFilter.Average: return (byte)(x + (a + b) / 2);
-				case PngFilter.Paeth: return (byte)(x + Paeth(a, b, c));
-				default:
-					throw new InvalidOperationException("Unsupported Filter");
-			}
-		}
-
-		static byte Paeth(byte a, byte b, byte c)
-		{
-			var p = a + b - c;
-			var pa = Math.Abs(p - a);
-			var pb = Math.Abs(p - b);
-			var pc = Math.Abs(p - c);
-
-			return (pa <= pb && pa <= pc) ? a :
-				(pb <= pc) ? b : c;
-		}
-
 		[Flags]
-		enum PngColorType { Indexed = 1, Color = 2, Alpha = 4 }
-		enum PngFilter { None, Sub, Up, Average, Paeth }
+		enum PngColorType : byte { Indexed = 1, Color = 2, Alpha = 4 }
+		enum PngFilter : byte { None, Sub, Up, Average, Paeth }
 
 		static bool IsPaletted(byte bitDepth, PngColorType colorType)
 		{
-			if (bitDepth == 8 && colorType == (PngColorType.Indexed | PngColorType.Color))
+			if (bitDepth <= 8 && colorType == (PngColorType.Indexed | PngColorType.Color))
 				return true;
 
 			if (bitDepth == 8 && colorType == (PngColorType.Color | PngColorType.Alpha))
@@ -246,16 +303,16 @@ namespace OpenRA.FileFormats
 			throw new InvalidDataException("Unknown pixel format");
 		}
 
-		void WritePngChunk(Stream output, string type, Stream input)
+		static void WritePngChunk(Stream output, string type, Stream input)
 		{
 			input.Position = 0;
 
 			var typeBytes = Encoding.ASCII.GetBytes(type);
 			output.Write(IPAddress.HostToNetworkOrder((int)input.Length));
-			output.WriteArray(typeBytes);
+			output.Write(typeBytes);
 
 			var data = input.ReadAllBytes();
-			output.WriteArray(data);
+			output.Write(data);
 
 			var crc32 = new Crc32();
 			crc32.Update(typeBytes);
@@ -267,16 +324,15 @@ namespace OpenRA.FileFormats
 		{
 			using (var output = new MemoryStream())
 			{
-				output.WriteArray(Signature);
+				output.Write(Signature);
 				using (var header = new MemoryStream())
 				{
 					header.Write(IPAddress.HostToNetworkOrder(Width));
 					header.Write(IPAddress.HostToNetworkOrder(Height));
 					header.WriteByte(8); // Bit depth
 
-					var colorType = Palette != null
-						? PngColorType.Indexed | PngColorType.Color
-						: PngColorType.Color | PngColorType.Alpha;
+					var colorType = Type == SpriteFrameType.Indexed8 ? PngColorType.Indexed | PngColorType.Color :
+						Type == SpriteFrameType.Rgb24 ? PngColorType.Color : PngColorType.Color | PngColorType.Alpha;
 					header.WriteByte((byte)colorType);
 
 					header.WriteByte(0); // Compression
@@ -286,7 +342,7 @@ namespace OpenRA.FileFormats
 					WritePngChunk(output, "IHDR", header);
 				}
 
-				bool alphaPalette = false;
+				var alphaPalette = false;
 				if (Palette != null)
 				{
 					using (var palette = new MemoryStream())
@@ -316,14 +372,15 @@ namespace OpenRA.FileFormats
 
 				using (var data = new MemoryStream())
 				{
-					using (var compressed = new DeflaterOutputStream(data))
+					using (var compressed = new DeflaterOutputStream(data, new Deflater(Deflater.BEST_COMPRESSION)))
 					{
-						var stride = Width * (Palette != null ? 1 : 4);
+						var rowStride = Width * PixelStride;
 						for (var y = 0; y < Height; y++)
 						{
-							// Write uncompressed scanlines for simplicity
-							compressed.WriteByte(0);
-							compressed.Write(Data, y * stride, stride);
+							// Assuming no filtering for simplicity
+							const byte FilterType = 0;
+							compressed.WriteByte(FilterType);
+							compressed.Write(Data, y * rowStride, rowStride);
 						}
 
 						compressed.Flush();
@@ -337,7 +394,7 @@ namespace OpenRA.FileFormats
 				{
 					using (var text = new MemoryStream())
 					{
-						text.WriteArray(Encoding.ASCII.GetBytes(kv.Key + (char)0 + kv.Value));
+						text.Write(Encoding.ASCII.GetBytes(kv.Key + (char)0 + kv.Value));
 						WritePngChunk(output, "tEXt", text);
 					}
 				}

OpenRA.Game/FileFormats/ReplayMetadata.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -28,7 +28,7 @@ namespace OpenRA.FileFormats
 		public ReplayMetadata(GameInformation info)
 		{
 			if (info == null)
-				throw new ArgumentNullException("info");
+				throw new ArgumentNullException(nameof(info));
 
 			GameInfo = info;
 		}
@@ -44,11 +44,11 @@ namespace OpenRA.FileFormats
 			// Read version
 			var version = fs.ReadInt32();
 			if (version != MetaVersion)
-				throw new NotSupportedException("Metadata version {0} is not supported".F(version));
+				throw new NotSupportedException($"Metadata version {version} is not supported");
 
 			// Read game info (max 100K limit as a safeguard against corrupted files)
-			var data = fs.ReadString(Encoding.UTF8, 1024 * 100);
-			GameInfo = GameInformation.Deserialize(data);
+			var data = fs.ReadLengthPrefixedString(Encoding.UTF8, 1024 * 100);
+			GameInfo = GameInformation.Deserialize(data, path);
 		}
 
 		public void Write(BinaryWriter writer)
@@ -62,7 +62,7 @@ namespace OpenRA.FileFormats
 			{
 				// Write lobby info data
 				writer.Flush();
-				dataLength += writer.BaseStream.WriteString(Encoding.UTF8, GameInfo.Serialize());
+				dataLength += writer.BaseStream.WriteLengthPrefixedString(Encoding.UTF8, GameInfo.Serialize());
 			}
 
 			// Write total length & end marker

OpenRA.Game/FileSystem/FileSystem.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -28,17 +28,17 @@ namespace OpenRA.FileSystem
 
 	public class FileSystem : IReadOnlyFileSystem
 	{
-		public IEnumerable<IReadOnlyPackage> MountedPackages { get { return mountedPackages.Keys; } }
-		readonly Dictionary<IReadOnlyPackage, int> mountedPackages = new Dictionary<IReadOnlyPackage, int>();
-		readonly Dictionary<string, IReadOnlyPackage> explicitMounts = new Dictionary<string, IReadOnlyPackage>();
+		public IEnumerable<IReadOnlyPackage> MountedPackages => mountedPackages.Keys;
+		readonly Dictionary<IReadOnlyPackage, int> mountedPackages = new();
+		readonly Dictionary<string, IReadOnlyPackage> explicitMounts = new();
 		readonly string modID;
 
 		// Mod packages that should not be disposed
-		readonly List<IReadOnlyPackage> modPackages = new List<IReadOnlyPackage>();
+		readonly List<IReadOnlyPackage> modPackages = new();
 		readonly IReadOnlyDictionary<string, Manifest> installedMods;
 		readonly IPackageLoader[] packageLoaders;
 
-		Cache<string, List<IReadOnlyPackage>> fileIndex = new Cache<string, List<IReadOnlyPackage>>(_ => new List<IReadOnlyPackage>());
+		Cache<string, List<IReadOnlyPackage>> fileIndex = new(_ => new List<IReadOnlyPackage>());
 
 		public FileSystem(string modID, IReadOnlyDictionary<string, Manifest> installedMods, IPackageLoader[] packageLoaders)
 		{
@@ -63,7 +63,7 @@ namespace OpenRA.FileSystem
 		{
 			// Raw directories are the easiest and one of the most common cases, so try these first
 			var resolvedPath = Platform.ResolvePath(filename);
-			if (!resolvedPath.Contains("|") && Directory.Exists(resolvedPath))
+			if (!resolvedPath.Contains('|') && Directory.Exists(resolvedPath))
 				return new Folder(resolvedPath);
 
 			// Children of another package require special handling
@@ -83,19 +83,19 @@ namespace OpenRA.FileSystem
 
 		public void Mount(string name, string explicitName = null)
 		{
-			var optional = name.StartsWith("~", StringComparison.Ordinal);
+			var optional = name.StartsWith('~');
 			if (optional)
-				name = name.Substring(1);
+				name = name[1..];
 
 			try
 			{
 				IReadOnlyPackage package;
-				if (name.StartsWith("$", StringComparison.Ordinal))
+				if (name.StartsWith('$'))
 				{
-					name = name.Substring(1);
+					name = name[1..];
 
 					if (!installedMods.TryGetValue(name, out var mod))
-						throw new InvalidOperationException("Could not load mod '{0}'. Available mods: {1}".F(name, installedMods.Keys.JoinWith(", ")));
+						throw new InvalidOperationException($"Could not load mod '{name}'. Available mods: {installedMods.Keys.JoinWith(", ")}");
 
 					package = mod.Package;
 					modPackages.Add(package);
@@ -104,15 +104,13 @@ namespace OpenRA.FileSystem
 				{
 					package = OpenPackage(name);
 					if (package == null)
-						throw new InvalidOperationException("Could not open package '{0}', file not found or its format is not supported.".F(name));
+						throw new InvalidOperationException($"Could not open package '{name}', file not found or its format is not supported.");
 				}
 
 				Mount(package, explicitName);
 			}
-			catch
+			catch when (optional)
 			{
-				if (!optional)
-					throw;
 			}
 		}
 
@@ -161,9 +159,7 @@ namespace OpenRA.FileSystem
 					explicitMounts.Remove(key);
 
 				// Mod packages aren't owned by us, so we shouldn't dispose them
-				if (modPackages.Contains(package))
-					modPackages.Remove(package);
-				else
+				if (!modPackages.Remove(package))
 					package.Dispose();
 			}
 			else
@@ -190,6 +186,12 @@ namespace OpenRA.FileSystem
 			UnmountAll();
 			foreach (var kv in manifest.Packages)
 				Mount(kv.Key, kv.Value);
+
+			mountedPackages.TrimExcess();
+			explicitMounts.TrimExcess();
+			modPackages.TrimExcess();
+			foreach (var packages in fileIndex.Values)
+				packages.TrimExcess();
 		}
 
 		Stream GetFromCache(string filename)
@@ -203,7 +205,7 @@ namespace OpenRA.FileSystem
 		public Stream Open(string filename)
 		{
 			if (!TryOpen(filename, out var s))
-				throw new FileNotFoundException("File not found: {0}".F(filename), filename);
+				throw new FileNotFoundException($"File not found: {filename}", filename);
 
 			return s;
 		}
@@ -211,9 +213,9 @@ namespace OpenRA.FileSystem
 		public bool TryGetPackageContaining(string path, out IReadOnlyPackage package, out string filename)
 		{
 			var explicitSplit = path.IndexOf('|');
-			if (explicitSplit > 0 && explicitMounts.TryGetValue(path.Substring(0, explicitSplit), out package))
+			if (explicitSplit > 0 && explicitMounts.TryGetValue(path[..explicitSplit], out package))
 			{
-				filename = path.Substring(explicitSplit + 1);
+				filename = path[(explicitSplit + 1)..];
 				return true;
 			}
 
@@ -226,14 +228,11 @@ namespace OpenRA.FileSystem
 		public bool TryOpen(string filename, out Stream s)
 		{
 			var explicitSplit = filename.IndexOf('|');
-			if (explicitSplit > 0)
+			if (explicitSplit > 0 && explicitMounts.TryGetValue(filename[..explicitSplit], out var explicitPackage))
 			{
-				if (explicitMounts.TryGetValue(filename.Substring(0, explicitSplit), out var explicitPackage))
-				{
-					s = explicitPackage.GetStream(filename.Substring(explicitSplit + 1));
-					if (s != null)
-						return true;
-				}
+				s = explicitPackage.GetStream(filename[(explicitSplit + 1)..]);
+				if (s != null)
+					return true;
 			}
 
 			s = GetFromCache(filename);
@@ -262,16 +261,16 @@ namespace OpenRA.FileSystem
 		public bool Exists(string filename)
 		{
 			var explicitSplit = filename.IndexOf('|');
-			if (explicitSplit > 0)
-				if (explicitMounts.TryGetValue(filename.Substring(0, explicitSplit), out var explicitPackage))
-					if (explicitPackage.Contains(filename.Substring(explicitSplit + 1)))
-						return true;
+			if (explicitSplit > 0 &&
+				explicitMounts.TryGetValue(filename[..explicitSplit], out var explicitPackage) &&
+				explicitPackage.Contains(filename[(explicitSplit + 1)..]))
+				return true;
 
 			return fileIndex.ContainsKey(filename);
 		}
 
 		/// <summary>
-		/// Returns true if the given filename references an external mod via an explicit mount
+		/// Returns true if the given filename references an external mod via an explicit mount.
 		/// </summary>
 		public bool IsExternalModFile(string filename)
 		{
@@ -279,7 +278,7 @@ namespace OpenRA.FileSystem
 			if (explicitSplit < 0)
 				return false;
 
-			if (!explicitMounts.TryGetValue(filename.Substring(0, explicitSplit), out var explicitPackage))
+			if (!explicitMounts.TryGetValue(filename[..explicitSplit], out var explicitPackage))
 				return false;
 
 			if (installedMods[modID].Package == explicitPackage)
@@ -295,21 +294,21 @@ namespace OpenRA.FileSystem
 		public static string ResolveAssemblyPath(string path, Manifest manifest, InstalledMods installedMods)
 		{
 			var explicitSplit = path.IndexOf('|');
-			if (explicitSplit > 0 && !path.StartsWith("^"))
+			if (explicitSplit > 0 && !path.StartsWith('^'))
 			{
-				var parent = path.Substring(0, explicitSplit);
-				var filename = path.Substring(explicitSplit + 1);
+				var parent = path[..explicitSplit];
+				var filename = path[(explicitSplit + 1)..];
 
 				var parentPath = manifest.Packages.FirstOrDefault(kv => kv.Value == parent).Key;
 				if (parentPath == null)
 					return null;
 
-				if (parentPath.StartsWith("$", StringComparison.Ordinal))
+				if (parentPath.StartsWith('$'))
 				{
-					if (!installedMods.TryGetValue(parentPath.Substring(1), out var mod))
+					if (!installedMods.TryGetValue(parentPath[1..], out var mod))
 						return null;
 
-					if (!(mod.Package is Folder))
+					if (mod.Package is not Folder)
 						return null;
 
 					path = Path.Combine(mod.Package.Name, filename);
@@ -322,6 +321,28 @@ namespace OpenRA.FileSystem
 			return File.Exists(resolvedPath) ? resolvedPath : null;
 		}
 
+		public static string ResolveCaseInsensitivePath(string path)
+		{
+			var resolved = Path.GetPathRoot(path);
+
+			if (resolved == null)
+				return null;
+
+			foreach (var name in path[resolved.Length..].Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar))
+			{
+				// Filter out paths of the form /foo/bar/./baz
+				if (name == ".")
+					continue;
+
+				resolved = Directory.GetFileSystemEntries(resolved).FirstOrDefault(e => e.Equals(Path.Combine(resolved, name), StringComparison.InvariantCultureIgnoreCase));
+
+				if (resolved == null)
+					return null;
+			}
+
+			return resolved;
+		}
+
 		public string GetPrefix(IReadOnlyPackage package)
 		{
 			return explicitMounts.ContainsValue(package) ? explicitMounts.First(f => f.Value == package).Key : null;

OpenRA.Game/FileSystem/Folder.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -18,24 +18,22 @@ namespace OpenRA.FileSystem
 {
 	public sealed class Folder : IReadWritePackage
 	{
-		readonly string path;
+		public string Name { get; }
 
 		public Folder(string path)
 		{
-			this.path = path;
+			Name = path;
 			if (!Directory.Exists(path))
 				Directory.CreateDirectory(path);
 		}
 
-		public string Name { get { return path; } }
-
 		public IEnumerable<string> Contents
 		{
 			get
 			{
 				// Order may vary on different file systems and it matters for hashing.
-				return Directory.GetFiles(path, "*", SearchOption.TopDirectoryOnly)
-					.Concat(Directory.GetDirectories(path))
+				return Directory.GetFiles(Name, "*", SearchOption.TopDirectoryOnly)
+					.Concat(Directory.GetDirectories(Name))
 					.Select(Path.GetFileName)
 					.OrderBy(f => f);
 			}
@@ -43,14 +41,18 @@ namespace OpenRA.FileSystem
 
 		public Stream GetStream(string filename)
 		{
-			try { return File.OpenRead(Path.Combine(path, filename)); }
+			var combined = Path.Combine(Name, filename);
+			if (!File.Exists(combined))
+				return null;
+
+			try { return File.OpenRead(combined); }
 			catch { return null; }
 		}
 
 		public bool Contains(string filename)
 		{
-			var combined = Path.Combine(path, filename);
-			return combined.StartsWith(path, StringComparison.Ordinal) && File.Exists(combined);
+			var combined = Path.Combine(Name, filename);
+			return combined.StartsWith(Name, StringComparison.Ordinal) && File.Exists(combined);
 		}
 
 		public IReadOnlyPackage OpenPackage(string filename, FileSystem context)
@@ -82,7 +84,7 @@ namespace OpenRA.FileSystem
 			// in FileSystem.OpenPackage.  Their internal name therefore contains the
 			// full parent path too.  We need to be careful to not add a second path
 			// prefix to these hacked packages.
-			var filePath = filename.StartsWith(path) ? filename : Path.Combine(path, filename);
+			var filePath = filename.StartsWith(Name, StringComparison.Ordinal) ? filename : Path.Combine(Name, filename);
 
 			Directory.CreateDirectory(Path.GetDirectoryName(filePath));
 			using (var s = File.Create(filePath))
@@ -96,7 +98,7 @@ namespace OpenRA.FileSystem
 			// in FileSystem.OpenPackage.  Their internal name therefore contains the
 			// full parent path too.  We need to be careful to not add a second path
 			// prefix to these hacked packages.
-			var filePath = filename.StartsWith(path) ? filename : Path.Combine(path, filename);
+			var filePath = filename.StartsWith(Name, StringComparison.Ordinal) ? filename : Path.Combine(Name, filename);
 			if (Directory.Exists(filePath))
 				Directory.Delete(filePath, true);
 			else if (File.Exists(filePath))

OpenRA.Game/FileSystem/IPackage.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of

OpenRA.Game/FileSystem/ZipFile.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -19,9 +19,9 @@ namespace OpenRA.FileSystem
 {
 	public class ZipFileLoader : IPackageLoader
 	{
-		static readonly string[] Extensions = { ".zip", ".oramap" };
+		const uint ZipSignature = 0x04034b50;
 
-		class ReadOnlyZipFile : IReadOnlyPackage
+		public class ReadOnlyZipFile : IReadOnlyPackage
 		{
 			public string Name { get; protected set; }
 			protected ZipFile pkg;
@@ -55,7 +55,8 @@ namespace OpenRA.FileSystem
 				get
 				{
 					foreach (ZipEntry entry in pkg)
-						yield return entry.Name;
+						if (entry.IsFile)
+							yield return entry.Name;
 				}
 			}
 
@@ -67,6 +68,7 @@ namespace OpenRA.FileSystem
 			public void Dispose()
 			{
 				pkg?.Close();
+				GC.SuppressFinalize(this);
 			}
 
 			public IReadOnlyPackage OpenPackage(string filename, FileSystem context)
@@ -92,9 +94,9 @@ namespace OpenRA.FileSystem
 			}
 		}
 
-		sealed class ReadWriteZipFile : ReadOnlyZipFile, IReadWritePackage
+		public sealed class ReadWriteZipFile : ReadOnlyZipFile, IReadWritePackage
 		{
-			readonly MemoryStream pkgStream = new MemoryStream();
+			readonly MemoryStream pkgStream = new();
 
 			public ReadWriteZipFile(string filename, bool create = false)
 			{
@@ -116,10 +118,7 @@ namespace OpenRA.FileSystem
 
 			void Commit()
 			{
-				var pos = pkgStream.Position;
-				pkgStream.Position = 0;
-				File.WriteAllBytes(Name, pkgStream.ReadBytes((int)pkgStream.Length));
-				pkgStream.Position = pos;
+				File.WriteAllBytes(Name, pkgStream.ToArray());
 			}
 
 			public void Update(string filename, byte[] contents)
@@ -141,23 +140,22 @@ namespace OpenRA.FileSystem
 
 		sealed class ZipFolder : IReadOnlyPackage
 		{
-			public string Name { get { return path; } }
-			public ReadOnlyZipFile Parent { get; private set; }
-			readonly string path;
+			public string Name { get; }
+			public ReadOnlyZipFile Parent { get; }
 
 			public ZipFolder(ReadOnlyZipFile parent, string path)
 			{
-				if (path.EndsWith("/", StringComparison.Ordinal))
-					path = path.Substring(0, path.Length - 1);
+				if (path.EndsWith('/'))
+					path = path[..^1];
 
+				Name = path;
 				Parent = parent;
-				this.path = path;
 			}
 
 			public Stream GetStream(string filename)
 			{
 				// Zip files use '/' as a path separator
-				return Parent.GetStream(path + '/' + filename);
+				return Parent.GetStream(Name + '/' + filename);
 			}
 
 			public IEnumerable<string> Contents
@@ -166,9 +164,9 @@ namespace OpenRA.FileSystem
 				{
 					foreach (var entry in Parent.Contents)
 					{
-						if (entry.StartsWith(path, StringComparison.Ordinal) && entry != path)
+						if (entry.StartsWith(Name, StringComparison.Ordinal) && entry != Name)
 						{
-							var filename = entry.Substring(path.Length + 1);
+							var filename = entry[(Name.Length + 1)..];
 							var dirLevels = filename.Split('/').Count(c => !string.IsNullOrEmpty(c));
 							if (dirLevels == 1)
 								yield return filename;
@@ -179,18 +177,18 @@ namespace OpenRA.FileSystem
 
 			public bool Contains(string filename)
 			{
-				return Parent.Contains(path + '/' + filename);
+				return Parent.Contains(Name + '/' + filename);
 			}
 
 			public IReadOnlyPackage OpenPackage(string filename, FileSystem context)
 			{
-				return Parent.OpenPackage(path + '/' + filename, context);
+				return Parent.OpenPackage(Name + '/' + filename, context);
 			}
 
 			public void Dispose() { /* nothing to do */ }
 		}
 
-		class StaticStreamDataSource : IStaticDataSource
+		sealed class StaticStreamDataSource : IStaticDataSource
 		{
 			readonly Stream s;
 			public StaticStreamDataSource(Stream s)
@@ -206,7 +204,10 @@ namespace OpenRA.FileSystem
 
 		public bool TryParsePackage(Stream s, string filename, FileSystem context, out IReadOnlyPackage package)
 		{
-			if (!Extensions.Any(e => filename.EndsWith(e, StringComparison.InvariantCultureIgnoreCase)))
+			var readSignature = s.ReadUInt32();
+			s.Position -= 4;
+
+			if (readSignature != ZipSignature)
 			{
 				package = null;
 				return false;
@@ -218,10 +219,13 @@ namespace OpenRA.FileSystem
 
 		public static bool TryParseReadWritePackage(string filename, out IReadWritePackage package)
 		{
-			if (!Extensions.Any(e => filename.EndsWith(e, StringComparison.InvariantCultureIgnoreCase)))
+			using (var s = File.OpenRead(filename))
 			{
-				package = null;
-				return false;
+				if (s.ReadUInt32() != ZipSignature)
+				{
+					package = null;
+					return false;
+				}
 			}
 
 			package = new ReadWriteZipFile(filename);

OpenRA.Game/Fonts.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,7 +22,7 @@ namespace OpenRA
 
 	public class Fonts : IGlobalModData
 	{
-		[FieldLoader.LoadUsing("LoadFonts")]
+		[FieldLoader.LoadUsing(nameof(LoadFonts))]
 		public readonly Dictionary<string, FontData> FontList;
 
 		static object LoadFonts(MiniYaml y)

OpenRA.Game/Game.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -16,10 +16,8 @@ using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Net;
-using System.Reflection;
 using System.Runtime;
 using System.Threading;
-using System.Threading.Tasks;
 using OpenRA.Graphics;
 using OpenRA.Network;
 using OpenRA.Primitives;
@@ -31,8 +29,9 @@ namespace OpenRA
 {
 	public static class Game
 	{
-		public const int NetTickScale = 3; // 120 ms net tick for 40 ms local tick
-		public const int Timestep = 40;
+		[TranslationReference("filename")]
+		const string SavedScreenshot = "notification-saved-screenshot";
+
 		public const int TimestepJankThreshold = 250; // Don't catch up for delays larger than 250ms
 
 		public static InstalledMods Mods { get; private set; }
@@ -42,13 +41,14 @@ namespace OpenRA
 		public static Settings Settings;
 		public static CursorManager Cursor;
 		public static bool HideCursor;
+
 		static WorldRenderer worldRenderer;
 		static string modLaunchWrapper;
 
 		internal static OrderManager OrderManager;
 		static Server.Server server;
 
-		public static MersenneTwister CosmeticRandom = new MersenneTwister(); // not synced
+		public static MersenneTwister CosmeticRandom = new(); // not synced
 
 		public static Renderer Renderer;
 		public static Sound Sound;
@@ -56,7 +56,6 @@ namespace OpenRA
 		public static string EngineVersion { get; private set; }
 		public static LocalPlayerProfile LocalPlayerProfile;
 
-		static Task discoverNat;
 		static bool takeScreenshot = false;
 		static Benchmark benchmark = null;
 
@@ -64,12 +63,18 @@ namespace OpenRA
 
 		public static OrderManager JoinServer(ConnectionTarget endpoint, string password, bool recordReplay = true)
 		{
-			var connection = new NetworkConnection(endpoint);
+			var newConnection = new NetworkConnection(endpoint);
 			if (recordReplay)
-				connection.StartRecording(() => { return TimestampedFilename(); });
+				newConnection.StartRecording(() => TimestampedFilename());
 
-			var om = new OrderManager(endpoint, password, connection);
+			var om = new OrderManager(newConnection);
 			JoinInner(om);
+			CurrentServerSettings.Password = password;
+			CurrentServerSettings.Target = endpoint;
+
+			lastConnectionState = ConnectionState.PreConnecting;
+			ConnectionStateChanged(OrderManager, password, newConnection);
+
 			return om;
 		}
 
@@ -81,34 +86,57 @@ namespace OpenRA
 
 		static void JoinInner(OrderManager om)
 		{
-			OrderManager?.Dispose();
+			// Refresh static classes before the game starts.
+			TextNotificationsManager.Clear();
+			UnitOrders.Clear();
+
+			// HACK: The shellmap World and OrderManager are owned by the main menu's WorldRenderer instead of Game.
+			// This allows us to switch Game.OrderManager from the shellmap to the new network connection when joining
+			// a lobby, while keeping the OrderManager that runs the shellmap intact.
+			// A matching check in World.Dispose (which is called by WorldRenderer.Dispose) makes sure that we dispose
+			// the shellmap's OM when a lobby game actually starts.
+			if (OrderManager?.World == null || OrderManager.World.Type != WorldType.Shellmap)
+				OrderManager?.Dispose();
+
 			OrderManager = om;
-			lastConnectionState = ConnectionState.PreConnecting;
-			ConnectionStateChanged(OrderManager);
 		}
 
 		public static void JoinReplay(string replayFile)
 		{
-			JoinInner(new OrderManager(new ConnectionTarget(), "", new ReplayConnection(replayFile)));
+			JoinInner(new OrderManager(new ReplayConnection(replayFile)));
 		}
 
 		static void JoinLocal()
 		{
-			JoinInner(new OrderManager(new ConnectionTarget(), "", new EchoConnection()));
+			JoinInner(new OrderManager(new EchoConnection()));
+
+			// Add a spectator client for the local player
+			// On the shellmap this player is controlling the map via scripted orders
+			OrderManager.LobbyInfo.Clients.Add(new Session.Client
+			{
+				Index = OrderManager.Connection.LocalClientId,
+				Name = Settings.Player.Name,
+				PreferredColor = Settings.Player.Color,
+				Color = Settings.Player.Color,
+				Faction = "Random",
+				SpawnPoint = 0,
+				Team = 0,
+				State = Session.ClientState.Ready
+			});
 		}
 
 		// More accurate replacement for Environment.TickCount
-		static Stopwatch stopwatch = Stopwatch.StartNew();
-		public static long RunTime { get { return stopwatch.ElapsedMilliseconds; } }
+		static readonly Stopwatch Stopwatch = Stopwatch.StartNew();
+		public static long RunTime => Stopwatch.ElapsedMilliseconds;
 
 		public static int RenderFrame = 0;
-		public static int NetFrameNumber { get { return OrderManager.NetFrameNumber; } }
-		public static int LocalTick { get { return OrderManager.LocalFrameNumber; } }
+		public static int NetFrameNumber => OrderManager.NetFrameNumber;
+		public static int LocalTick => OrderManager.LocalFrameNumber;
 
 		public static event Action<ConnectionTarget> OnRemoteDirectConnect = _ => { };
-		public static event Action<OrderManager> ConnectionStateChanged = _ => { };
+		public static event Action<OrderManager, string, NetworkConnection> ConnectionStateChanged = (om, pass, conn) => { };
 		static ConnectionState lastConnectionState = ConnectionState.PreConnecting;
-		public static int LocalClientId { get { return OrderManager.Connection.LocalClientId; } }
+		public static int LocalClientId => OrderManager.Connection.LocalClientId;
 
 		public static void RemoteDirectConnect(ConnectionTarget endpoint)
 		{
@@ -152,6 +180,7 @@ namespace OpenRA
 		}
 
 		public static event Action BeforeGameStart = () => { };
+		public static event Action AfterGameStart = () => { };
 		internal static void StartGame(string mapUID, WorldType type)
 		{
 			// Dispose of the old world before creating a new one.
@@ -160,12 +189,8 @@ namespace OpenRA
 			Cursor.SetCursor(null);
 			BeforeGameStart();
 
-			Map map;
-
-			using (new PerfTimer("PrepareMap"))
-				map = ModData.PrepareMap(mapUID);
 			using (new PerfTimer("NewWorld"))
-				OrderManager.World = new World(ModData, map, OrderManager, type);
+				OrderManager.World = new World(mapUID, ModData, OrderManager, type);
 
 			OrderManager.World.GameOver += FinishBenchmark;
 
@@ -186,11 +211,9 @@ namespace OpenRA
 			Ui.MouseFocusWidget = null;
 			Ui.KeyboardFocusWidget = null;
 
-			OrderManager.LocalFrameNumber = 0;
-			OrderManager.LastTickTime = RunTime;
 			OrderManager.StartGame();
 			worldRenderer.RefreshPalette();
-			Cursor.SetCursor("default");
+			Cursor.SetCursor(ChromeMetrics.Get<string>("DefaultCursor"));
 
 			// Now loading is completed, now is the ideal time to run a GC and compact the LOH.
 			// - All the temporary garbage created during loading can be collected.
@@ -201,20 +224,37 @@ namespace OpenRA
 			//   Much better to clean up now then to drop frames during gameplay for GC pauses.
 			GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
 			GC.Collect();
+
+			// PostLoadComplete is designed for anything that should trigger at the very end of loading.
+			// e.g. audio notifications that the game is starting.
+			OrderManager.World.PostLoadComplete(worldRenderer);
+
+			AfterGameStart();
 		}
 
 		public static void RestartGame()
 		{
 			var replay = OrderManager.Connection as ReplayConnection;
-			var replayName = replay != null ? replay.Filename : null;
+			var replayName = replay?.Filename;
 			var lobbyInfo = OrderManager.LobbyInfo;
 
 			// Reseed the RNG so this isn't an exact repeat of the last game
 			lobbyInfo.GlobalSettings.RandomSeed = CosmeticRandom.Next();
 
+			// Note: the map may have been changed on disk outside the game, changing its UID.
+			// Use the updated UID if we have tracked the update instead of failing.
+			lobbyInfo.GlobalSettings.Map = ModData.MapCache.GetUpdatedMap(lobbyInfo.GlobalSettings.Map);
+			if (lobbyInfo.GlobalSettings.Map == null)
+			{
+				Disconnect();
+				Ui.ResetAll();
+				LoadShellMap();
+				return;
+			}
+
 			var orders = new[]
 			{
-					Order.Command("sync_lobby {0}".F(lobbyInfo.Serialize())),
+					Order.Command($"sync_lobby {lobbyInfo.Serialize()}"),
 					Order.Command("startgame")
 			};
 
@@ -233,15 +273,14 @@ namespace OpenRA
 		{
 			OrderManager om = null;
 
-			Action lobbyReady = null;
-			lobbyReady = () =>
+			void LobbyReady()
 			{
-				LobbyInfoChanged -= lobbyReady;
+				LobbyInfoChanged -= LobbyReady;
 				foreach (var o in setupOrders)
 					om.IssueOrder(o);
-			};
+			}
 
-			LobbyInfoChanged += lobbyReady;
+			LobbyInfoChanged += LobbyReady;
 
 			om = JoinServer(CreateLocalServer(mapUID), "");
 		}
@@ -284,7 +323,7 @@ namespace OpenRA
 			if (!string.IsNullOrEmpty(supportDirArg))
 				Platform.OverrideSupportDir(supportDirArg);
 
-			Console.WriteLine("Platform is {0}", Platform.CurrentPlatform);
+			Console.WriteLine($"Platform is {Platform.CurrentPlatform} ({Platform.CurrentArchitecture})");
 
 			// Load the engine version as early as possible so it can be written to exception logs
 			try
@@ -296,12 +335,13 @@ namespace OpenRA
 			if (string.IsNullOrEmpty(EngineVersion))
 				EngineVersion = "Unknown";
 
-			Console.WriteLine("Engine version is {0}", EngineVersion);
+			Console.WriteLine($"Engine version is {EngineVersion}");
+			Console.WriteLine($"Runtime: {Platform.RuntimeVersion}");
 
 			// Special case handling of Game.Mod argument: if it matches a real filesystem path
 			// then we use this to override the mod search path, and replace it with the mod id
 			var modID = args.GetValue("Game.Mod", null);
-			var explicitModPaths = new string[0];
+			var explicitModPaths = Array.Empty<string>();
 			if (modID != null && (File.Exists(modID) || Directory.Exists(modID)))
 			{
 				explicitModPaths = new[] { modID };
@@ -329,9 +369,17 @@ namespace OpenRA
 				try
 				{
 					var rendererPath = Path.Combine(Platform.BinDir, "OpenRA.Platforms." + p + ".dll");
-					var assembly = Assembly.LoadFile(rendererPath);
 
+#if NET5_0_OR_GREATER
+					var loader = new AssemblyLoader(rendererPath);
+					var platformType = loader.LoadDefaultAssembly().GetTypes().SingleOrDefault(t => typeof(IPlatform).IsAssignableFrom(t));
+
+#else
+					// NOTE: This is currently the only use of System.Reflection in this file, so would give an unused using error if we import it above
+					var assembly = System.Reflection.Assembly.LoadFile(rendererPath);
 					var platformType = assembly.GetTypes().SingleOrDefault(t => typeof(IPlatform).IsAssignableFrom(t));
+#endif
+
 					if (platformType == null)
 						throw new InvalidOperationException("Platform dll must include exactly one IPlatform implementation.");
 
@@ -343,7 +391,7 @@ namespace OpenRA
 				}
 				catch (Exception e)
 				{
-					Log.Write("graphics", "{0}", e);
+					Log.Write("graphics", $"{e}");
 					Console.WriteLine("Renderer initialization failed. Check graphics.log for details.");
 
 					Renderer?.Dispose();
@@ -352,8 +400,7 @@ namespace OpenRA
 				}
 			}
 
-			if (Settings.Server.DiscoverNatDevices)
-				discoverNat = UPnP.DiscoverNatDevices(Settings.Server.NatDiscoveryTimeout);
+			Nat.Initialize();
 
 			var modSearchArg = args.GetValue("Engine.ModSearchPaths", null);
 			var modSearchPaths = modSearchArg != null ?
@@ -363,7 +410,7 @@ namespace OpenRA
 			Mods = new InstalledMods(modSearchPaths, explicitModPaths);
 			Console.WriteLine("Internal mods:");
 			foreach (var mod in Mods)
-				Console.WriteLine("\t{0}: {1} ({2})", mod.Key, mod.Value.Metadata.Title, mod.Value.Metadata.Version);
+				Console.WriteLine($"\t{mod.Key}: {mod.Value.Metadata.Title} ({mod.Value.Metadata.Version})");
 
 			modLaunchWrapper = args.GetValue("Engine.LaunchWrapper", null);
 
@@ -376,27 +423,19 @@ namespace OpenRA
 
 				// Sanitize input from platform-specific launchers
 				// Process.Start requires paths to not be quoted, even if they contain spaces
-				if (launchPath != null && launchPath.First() == '"' && launchPath.Last() == '"')
-					launchPath = launchPath.Substring(1, launchPath.Length - 2);
+				if (launchPath != null && launchPath[0] == '"' && launchPath.Last() == '"')
+					launchPath = launchPath[1..^1];
 
-				if (launchPath == null)
-				{
-					// When launching the assembly directly we must propagate the Engine.EngineDir argument if defined
-					// Platform-specific launchers are expected to manage this internally.
-					launchPath = Assembly.GetEntryAssembly().Location;
-					if (!string.IsNullOrEmpty(engineDirArg))
-						launchArgs.Add("Engine.EngineDir=\"" + engineDirArg + "\"");
-				}
+				// Metadata registration requires an explicit launch path
+				if (launchPath != null)
+					ExternalMods.Register(Mods[modID], launchPath, launchArgs, ModRegistration.User);
 
-				ExternalMods.Register(Mods[modID], launchPath, launchArgs, ModRegistration.User);
-
-				if (ExternalMods.TryGetValue(ExternalMod.MakeKey(Mods[modID]), out var activeMod))
-					ExternalMods.ClearInvalidRegistrations(activeMod, ModRegistration.User);
+				ExternalMods.ClearInvalidRegistrations(ModRegistration.User);
 			}
 
 			Console.WriteLine("External mods:");
 			foreach (var mod in ExternalMods)
-				Console.WriteLine("\t{0}: {1} ({2})", mod.Key, mod.Value.Title, mod.Value.Version);
+				Console.WriteLine($"\t{mod.Key}: {mod.Value.Title} ({mod.Value.Version})");
 
 			InitializeMod(modID, args);
 		}
@@ -405,7 +444,7 @@ namespace OpenRA
 		{
 			// Clear static state if we have switched mods
 			LobbyInfoChanged = () => { };
-			ConnectionStateChanged = om => { };
+			ConnectionStateChanged = (om, p, conn) => { };
 			BeforeGameStart = () => { };
 			OnRemoteDirectConnect = endpoint => { };
 			delayedActions = new ActionQueue();
@@ -429,9 +468,9 @@ namespace OpenRA
 				throw new InvalidOperationException("Game.Mod argument missing.");
 
 			if (!Mods.ContainsKey(mod))
-				throw new InvalidOperationException("Unknown or invalid mod '{0}'.".F(mod));
+				throw new InvalidOperationException($"Unknown or invalid mod '{mod}'.");
 
-			Console.WriteLine("Loading mod: {0}", mod);
+			Console.WriteLine($"Loading mod: {mod}");
 
 			Sound.StopVideo();
 
@@ -442,19 +481,22 @@ namespace OpenRA
 			if (!ModData.LoadScreen.BeforeLoad())
 				return;
 
-			using (new PerfTimer("LoadMaps"))
-				ModData.MapCache.LoadMaps();
-
 			ModData.InitializeLoaders(ModData.DefaultFileSystem);
 			Renderer.InitializeFonts(ModData);
 
+			using (new PerfTimer("LoadMaps"))
+				ModData.MapCache.LoadMaps();
+
 			var grid = ModData.Manifest.Contains<MapGrid>() ? ModData.Manifest.Get<MapGrid>() : null;
 			Renderer.InitializeDepthBuffer(grid);
 
 			Cursor?.Dispose();
-
 			Cursor = new CursorManager(ModData.CursorProvider);
 
+			var metadata = ModData.Manifest.Metadata;
+			if (!string.IsNullOrEmpty(metadata.WindowTitle))
+				Renderer.Window.SetWindowTitle(metadata.WindowTitle);
+
 			PerfHistory.Items["render"].HasNormalTick = false;
 			PerfHistory.Items["batches"].HasNormalTick = false;
 			PerfHistory.Items["render_world"].HasNormalTick = false;
@@ -464,31 +506,18 @@ namespace OpenRA
 
 			JoinLocal();
 
-			try
-			{
-				discoverNat?.Wait();
-			}
-			catch (Exception e)
-			{
-				Console.WriteLine("NAT discovery failed: {0}", e.Message);
-				Log.Write("nat", e.ToString());
-			}
-
-			ChromeMetrics.TryGet("ChatMessageColor", out chatMessageColor);
-			ChromeMetrics.TryGet("SystemMessageColor", out systemMessageColor);
-
 			ModData.LoadScreen.StartGame(args);
 		}
 
 		public static void LoadEditor(string mapUid)
 		{
+			JoinLocal();
 			StartGame(mapUid, WorldType.Editor);
 		}
 
 		public static void LoadShellMap()
 		{
 			var shellmap = ChooseShellmap();
-
 			using (new PerfTimer("StartGame"))
 			{
 				StartGame(shellmap, WorldType.Shellmap);
@@ -502,10 +531,11 @@ namespace OpenRA
 				.Where(m => m.Status == MapStatus.Available && m.Visibility.HasFlag(MapVisibility.Shellmap))
 				.Select(m => m.Uid);
 
-			if (!shellmaps.Any())
+			var shellmap = shellmaps.RandomOrDefault(CosmeticRandom);
+			if (shellmap == null)
 				throw new InvalidDataException("No valid shellmaps available");
 
-			return shellmaps.Random(CosmeticRandom);
+			return shellmap;
 		}
 
 		public static void SwitchToExternalMod(ExternalMod mod, string[] launchArguments = null, Action onFailed = null)
@@ -542,9 +572,8 @@ namespace OpenRA
 
 		// Note: These delayed actions should only be used by widgets or disposing objects
 		// - things that depend on a particular world should be queuing them on the world actor.
-		static volatile ActionQueue delayedActions = new ActionQueue();
-		static Color systemMessageColor = Color.White;
-		static Color chatMessageColor = Color.White;
+		static volatile ActionQueue delayedActions = new();
+
 		public static void RunAfterTick(Action a) { delayedActions.Add(a, RunTime); }
 		public static void RunAfterDelay(int delayMilliseconds, Action a) { delayedActions.Add(a, RunTime + delayMilliseconds); }
 
@@ -561,7 +590,7 @@ namespace OpenRA
 				Log.Write("debug", "Taking screenshot " + path);
 
 				Renderer.SaveScreenshot(path);
-				Debug("Saved screenshot " + filename);
+				TextNotificationsManager.Debug(TranslationProvider.GetString(SavedScreenshot, Translation.Arguments("filename", filename)));
 			}
 		}
 
@@ -571,62 +600,45 @@ namespace OpenRA
 
 			var world = orderManager.World;
 
-			var uiTickDelta = tick - Ui.LastTickTime;
-			if (uiTickDelta >= Timestep)
+			if (Ui.LastTickTime.ShouldAdvance(tick))
 			{
-				// Explained below for the world tick calculation
-				var integralTickTimestep = (uiTickDelta / Timestep) * Timestep;
-				Ui.LastTickTime += integralTickTimestep >= TimestepJankThreshold ? integralTickTimestep : Timestep;
-
-				Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, Ui.Tick);
+				Ui.LastTickTime.AdvanceTickTime(tick);
+				Sync.RunUnsynced(world, Ui.Tick);
 				Cursor.Tick();
 			}
 
-			var worldTimestep = world == null ? Timestep : world.IsLoadingGameSave ? 1 : world.Timestep;
-			var worldTickDelta = tick - orderManager.LastTickTime;
-			if (worldTimestep != 0 && worldTickDelta >= worldTimestep)
+			if (orderManager.LastTickTime.ShouldAdvance(tick))
 			{
-				using (new PerfSample("tick_time"))
+				if (orderManager.GameStarted && orderManager.LocalFrameNumber == 0)
+					PerfHistory.Reset(); // Remove history that occurred whilst the new game was loading.
+
+				using (var sample = new PerfSample("tick_time"))
 				{
-					// Tick the world to advance the world time to match real time:
-					//    If dt < TickJankThreshold then we should try and catch up by repeatedly ticking
-					//    If dt >= TickJankThreshold then we should accept the jank and progress at the normal rate
-					// dt is rounded down to an integer tick count in order to preserve fractional tick components.
-					var integralTickTimestep = (worldTickDelta / worldTimestep) * worldTimestep;
-					orderManager.LastTickTime += integralTickTimestep >= TimestepJankThreshold ? integralTickTimestep : worldTimestep;
+					orderManager.LastTickTime.AdvanceTickTime(tick);
 
 					Sound.Tick();
-					Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, orderManager.TickImmediate);
+
+					Sync.RunUnsynced(world, orderManager.TickImmediate);
 
 					if (world == null)
-						return;
-
-					var isNetTick = LocalTick % NetTickScale == 0;
-
-					if (!isNetTick || orderManager.IsReadyForNextFrame)
 					{
-						++orderManager.LocalFrameNumber;
+						if (orderManager.GameStarted)
+							PerfHistory.Reset(); // Remove old history when a new game starts.
+						return;
+					}
 
-						Log.Write("debug", "--Tick: {0} ({1})", LocalTick, isNetTick ? "net" : "local");
-
-						if (isNetTick)
-							orderManager.Tick();
-
-						Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, () =>
-						{
-							world.OrderGenerator.Tick(world);
-						});
+					if (orderManager.TryTick())
+					{
+						Sync.RunUnsynced(world, () => world.OrderGenerator.Tick(world));
 
 						world.Tick();
 
 						PerfHistory.Tick();
 					}
-					else if (orderManager.NetFrameNumber == 0)
-						orderManager.LastTickTime = RunTime;
 
 					// Wait until we have done our first world Tick before TickRendering
 					if (orderManager.LocalFrameNumber > 0)
-						Sync.RunUnsynced(Settings.Debug.SyncCheckUnsyncedCode, world, () => world.TickRender(worldRenderer));
+						Sync.RunUnsynced(world, () => world.TickRender(worldRenderer));
 				}
 
 				benchmark?.Tick(LocalTick);
@@ -637,10 +649,10 @@ namespace OpenRA
 		{
 			PerformDelayedActions();
 
-			if (OrderManager.Connection.ConnectionState != lastConnectionState)
+			if (OrderManager.Connection is NetworkConnection nc && nc.ConnectionState != lastConnectionState)
 			{
-				lastConnectionState = OrderManager.Connection.ConnectionState;
-				ConnectionStateChanged(OrderManager);
+				lastConnectionState = nc.ConnectionState;
+				ConnectionStateChanged(OrderManager, null, nc);
 			}
 
 			InnerLogicTick(OrderManager);
@@ -667,7 +679,7 @@ namespace OpenRA
 				// Prepare renderables (i.e. render voxels) before calling BeginFrame
 				using (new PerfSample("render_prepare"))
 				{
-					Renderer.WorldModelRenderer.BeginFrame();
+					worldRenderer?.BeginFrame();
 
 					// World rendering is disabled while the loading screen is displayed
 					if (worldRenderer != null && !worldRenderer.World.IsLoadingGameSave)
@@ -677,7 +689,7 @@ namespace OpenRA
 					}
 
 					Ui.PrepareRenderables();
-					Renderer.WorldModelRenderer.EndFrame();
+					worldRenderer?.EndFrame();
 				}
 
 				// worldRenderer is null during the initial install/download screen
@@ -777,13 +789,20 @@ namespace OpenRA
 
 			while (state == RunStatus.Running)
 			{
-				// Ideal time between logic updates. Timestep = 0 means the game is paused
-				// but we still call LogicTick() because it handles pausing internally.
-				var logicInterval = worldRenderer != null && worldRenderer.World.Timestep != 0 ? worldRenderer.World.Timestep : Timestep;
+				var logicInterval = Ui.Timestep;
+				var logicWorld = worldRenderer?.World;
+
+				// ReplayTimestep = 0 means the replay is paused: we need to keep logicInterval as UI.Timestep to avoid breakage
+				if (logicWorld != null && (!logicWorld.IsReplay || logicWorld.ReplayTimestep != 0))
+					logicInterval = logicWorld == OrderManager.World ? OrderManager.SuggestedTimestep : logicWorld.Timestep;
 
 				// Ideal time between screen updates
-				var maxFramerate = Settings.Graphics.CapFramerate ? Settings.Graphics.MaxFramerate.Clamp(1, 1000) : 1000;
-				var renderInterval = 1000 / maxFramerate;
+				var renderInterval = logicInterval;
+				if (!Settings.Graphics.CapFramerateToGameFps)
+				{
+					var maxFramerate = Settings.Graphics.CapFramerate ? Settings.Graphics.MaxFramerate.Clamp(1, 1000) : 1000;
+					renderInterval = 1000 / maxFramerate;
+				}
 
 				// Tick as fast as possible while restoring game saves, capping rendering at 5 FPS
 				if (OrderManager.World != null && OrderManager.World.IsLoadingGameSave)
@@ -817,8 +836,7 @@ namespace OpenRA
 
 					var haveSomeTimeUntilNextLogic = now < nextLogic;
 					var isTimeToRender = now >= nextRender;
-
-					if ((isTimeToRender && haveSomeTimeUntilNextLogic) || forceRender)
+					if (!Renderer.WindowIsSuspended && ((isTimeToRender && haveSomeTimeUntilNextLogic) || forceRender))
 					{
 						nextRender = now + renderInterval;
 
@@ -833,6 +851,19 @@ namespace OpenRA
 						RenderTick();
 						renderBeforeNextTick = false;
 					}
+
+					// Simulate a render tick if it was time to render but we skip actually rendering
+					if (Renderer.WindowIsSuspended && isTimeToRender)
+					{
+						// Make sure that nextUpdate is set to a proper minimum interval
+						nextRender = now + renderInterval;
+
+						// Still process SDL events to allow a restore to come through
+						Renderer.Window.PumpInput(new NullInputHandler());
+
+						// Ensure that we still logic tick despite not rendering
+						renderBeforeNextTick = false;
+					}
 				}
 				else
 					Thread.Sleep((int)(nextUpdate - now));
@@ -874,26 +905,6 @@ namespace OpenRA
 			state = RunStatus.Success;
 		}
 
-		public static void AddSystemLine(string text)
-		{
-			AddSystemLine("Battlefield Control", text);
-		}
-
-		public static void AddSystemLine(string name, string text)
-		{
-			OrderManager.AddChatLine(name, systemMessageColor, text, systemMessageColor);
-		}
-
-		public static void AddChatLine(string name, Color nameColor, string text)
-		{
-			OrderManager.AddChatLine(name, nameColor, text, chatMessageColor);
-		}
-
-		public static void Debug(string s, params object[] args)
-		{
-			AddSystemLine("Debug", string.Format(s, args));
-		}
-
 		public static void Disconnect()
 		{
 			OrderManager.World?.TraitDict.PrintReport();
@@ -917,15 +928,15 @@ namespace OpenRA
 		{
 			var endpoints = new List<IPEndPoint>
 			{
-				new IPEndPoint(IPAddress.IPv6Any, settings.ListenPort),
-				new IPEndPoint(IPAddress.Any, settings.ListenPort)
+				new(IPAddress.IPv6Any, settings.ListenPort),
+				new(IPAddress.Any, settings.ListenPort)
 			};
 			server = new Server.Server(endpoints, settings, ModData, ServerType.Multiplayer);
 
 			return server.GetEndpointForLocalConnection();
 		}
 
-		public static ConnectionTarget CreateLocalServer(string map)
+		public static ConnectionTarget CreateLocalServer(string map, bool isSkirmish = false)
 		{
 			var settings = new ServerSettings()
 			{
@@ -939,9 +950,9 @@ namespace OpenRA
 			// This would break the Restart button, which relies on the PlayerIndex always being the same for local servers
 			var endpoints = new List<IPEndPoint>
 			{
-				new IPEndPoint(IPAddress.Loopback, 0)
+				new(IPAddress.Loopback, 0)
 			};
-			server = new Server.Server(endpoints, settings, ModData, ServerType.Local);
+			server = new Server.Server(endpoints, settings, ModData, isSkirmish ? ServerType.Skirmish : ServerType.Local);
 
 			return server.GetEndpointForLocalConnection();
 		}
@@ -965,16 +976,13 @@ namespace OpenRA
 		{
 			var orders = new List<Order>
 			{
-				Order.Command("option gamespeed {0}".F("default")),
-				Order.Command("state {0}".F(Session.ClientState.Ready))
+				Order.Command("option gamespeed default"),
+				Order.Command($"state {Session.ClientState.Ready}")
 			};
 
-			var path = Platform.ResolvePath(launchMap);
-			var map = ModData.MapCache.SingleOrDefault(m => m.Uid == launchMap) ??
-				ModData.MapCache.SingleOrDefault(m => m.Package.Name == path);
-
+			var map = ModData.MapCache.SingleOrDefault(m => m.Uid == launchMap || Path.GetFileName(m.Package.Name) == launchMap);
 			if (map == null)
-				throw new InvalidOperationException("Could not find map '{0}'.".F(launchMap));
+				throw new ArgumentException($"Could not find map '{launchMap}'.");
 
 			CreateAndStartLocalServer(map.Uid, orders);
 		}
@@ -988,4 +996,11 @@ namespace OpenRA
 			}
 		}
 	}
+
+	public static class CurrentServerSettings
+	{
+		public static string Password;
+		public static ConnectionTarget Target;
+		public static ExternalMod ServerExternalMod;
+	}
 }

OpenRA.Game/GameInformation.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -33,12 +33,13 @@ namespace OpenRA
 		public DateTime EndTimeUtc;
 
 		/// <summary>Gets the game's duration, from the time the game started until the replay recording stopped.</summary>
-		public TimeSpan Duration { get { return EndTimeUtc > StartTimeUtc ? EndTimeUtc - StartTimeUtc : TimeSpan.Zero; } }
-		public IList<Player> Players { get; private set; }
-		public HashSet<int> DisabledSpawnPoints = new HashSet<int>();
-		public MapPreview MapPreview { get { return Game.ModData.MapCache[MapUid]; } }
+		public TimeSpan Duration => EndTimeUtc > StartTimeUtc ? EndTimeUtc - StartTimeUtc : TimeSpan.Zero;
+
+		public IList<Player> Players { get; }
+		public HashSet<int> DisabledSpawnPoints = new();
+		public MapPreview MapPreview => Game.ModData.MapCache[MapUid];
 		public IEnumerable<Player> HumanPlayers { get { return Players.Where(p => p.IsHuman); } }
-		public bool IsSinglePlayer { get { return HumanPlayers.Count() == 1; } }
+		public bool IsSinglePlayer => HumanPlayers.Count() == 1;
 
 		readonly Dictionary<OpenRA.Player, Player> playersByRuntime;
 
@@ -48,13 +49,13 @@ namespace OpenRA
 			playersByRuntime = new Dictionary<OpenRA.Player, Player>();
 		}
 
-		public static GameInformation Deserialize(string data)
+		public static GameInformation Deserialize(string data, string path)
 		{
 			try
 			{
 				var info = new GameInformation();
 
-				var nodes = MiniYaml.FromString(data);
+				var nodes = MiniYaml.FromString(data, path);
 				foreach (var node in nodes)
 				{
 					var keyParts = node.Key.Split('@');
@@ -75,7 +76,7 @@ namespace OpenRA
 			}
 			catch (YamlException)
 			{
-				Log.Write("debug", "GameInformation deserialized invalid MiniYaml:\n{0}".F(data));
+				Log.Write("debug", $"GameInformation deserialized invalid MiniYaml:\n{data}");
 				throw;
 			}
 		}
@@ -84,11 +85,11 @@ namespace OpenRA
 		{
 			var nodes = new List<MiniYamlNode>
 			{
-				new MiniYamlNode("Root", FieldSaver.Save(this))
+				new("Root", FieldSaver.Save(this))
 			};
 
 			for (var i = 0; i < Players.Count; i++)
-				nodes.Add(new MiniYamlNode("Player@{0}".F(i), FieldSaver.Save(Players[i])));
+				nodes.Add(new MiniYamlNode($"Player@{i}", FieldSaver.Save(Players[i])));
 
 			return nodes.WriteToString();
 		}
@@ -97,10 +98,10 @@ namespace OpenRA
 		public void AddPlayer(OpenRA.Player runtimePlayer, Session lobbyInfo)
 		{
 			if (runtimePlayer == null)
-				throw new ArgumentNullException("runtimePlayer");
+				throw new ArgumentNullException(nameof(runtimePlayer));
 
 			if (lobbyInfo == null)
-				throw new ArgumentNullException("lobbyInfo");
+				throw new ArgumentNullException(nameof(lobbyInfo));
 
 			// We don't care about spectators and map players
 			if (runtimePlayer.NonCombatant || !runtimePlayer.Playable)
@@ -123,6 +124,7 @@ namespace OpenRA
 				DisplayFactionId = runtimePlayer.DisplayFaction.InternalName,
 				Color = runtimePlayer.Color,
 				Team = client.Team,
+				Handicap = client.Handicap,
 				SpawnPoint = runtimePlayer.SpawnPoint,
 				IsRandomFaction = runtimePlayer.Faction.InternalName != client.Faction,
 				IsRandomSpawnPoint = runtimePlayer.DisplaySpawnPoint == 0,
@@ -166,6 +168,7 @@ namespace OpenRA
 			/// <summary>The team ID on start-up, or 0 if the player is not part of a team.</summary>
 			public int Team;
 			public int SpawnPoint;
+			public int Handicap;
 
 			/// <summary>True if the faction was chosen at random; otherwise, false.</summary>
 			public bool IsRandomFaction;

OpenRA.Game/GameRules/ActorInfo.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,7 +22,7 @@ namespace OpenRA
 	/// </summary>
 	public class ActorInfo
 	{
-		public const string AbstractActorPrefix = "^";
+		public const char AbstractActorPrefix = '^';
 		public const char TraitInstanceSeparator = '@';
 
 		/// <summary>
@@ -32,7 +32,7 @@ namespace OpenRA
 		/// You can remove inherited traits by adding a - in front of them as in -TraitName: to inherit everything, but this trait.
 		/// </summary>
 		public readonly string Name;
-		readonly TypeDictionary traits = new TypeDictionary();
+		readonly TypeDictionary traits = new();
 		List<TraitInfo> constructOrderCache = null;
 
 		public ActorInfo(ObjectCreator creator, string name, MiniYaml node)
@@ -61,7 +61,7 @@ namespace OpenRA
 			}
 			catch (YamlException e)
 			{
-				throw new YamlException("Actor type {0}: {1}".F(name, e.Message));
+				throw new YamlException($"Actor type {name}: {e.Message}");
 			}
 		}
 
@@ -76,8 +76,7 @@ namespace OpenRA
 		static TraitInfo LoadTraitInfo(ObjectCreator creator, string traitName, MiniYaml my)
 		{
 			if (!string.IsNullOrEmpty(my.Value))
-				throw new YamlException("Junk value `{0}` on trait node {1}"
-				.F(my.Value, traitName));
+				throw new YamlException($"Junk value `{my.Value}` on trait node {traitName}");
 
 			// HACK: The linter does not want to crash when a trait doesn't exist but only print an error instead
 			// ObjectCreator will only return null to signal us to abort here if the linter is running
@@ -89,7 +88,7 @@ namespace OpenRA
 			try
 			{
 				if (traitInstance.Length > 1)
-					info.GetType().GetField("InstanceName").SetValue(info, traitInstance[1]);
+					info.GetType().GetField(nameof(info.InstanceName)).SetValue(info, traitInstance[1]);
 
 				FieldLoader.Load(info, my);
 			}
@@ -111,45 +110,59 @@ namespace OpenRA
 			{
 				Trait = i,
 				Type = i.GetType(),
-				Dependencies = PrerequisitesOf(i).ToList()
+				Dependencies = PrerequisitesOf(i).ToList(),
+				OptionalDependencies = OptionalPrerequisitesOf(i).ToList()
 			}).ToList();
 
-			var resolved = source.Where(s => !s.Dependencies.Any()).ToList();
-			var unresolved = source.Except(resolved);
+			var resolved = source.Where(s => s.Dependencies.Count == 0 && s.OptionalDependencies.Count == 0).ToList();
+			var unresolved = source.ToHashSet();
+			unresolved.ExceptWith(resolved);
 
-			var testResolve = new Func<Type, Type, bool>((a, b) => a == b || a.IsAssignableFrom(b));
+			static bool AreResolvable(Type a, Type b) => a.IsAssignableFrom(b);
 
 			// This query detects which unresolved traits can be immediately resolved as all their direct dependencies are met.
 			var more = unresolved.Where(u =>
 				u.Dependencies.All(d => // To be resolvable, all dependencies must be satisfied according to the following conditions:
-					resolved.Exists(r => testResolve(d, r.Type)) && // There must exist a resolved trait that meets the dependency.
-					!unresolved.Any(u1 => testResolve(d, u1.Type)))); // All matching traits that meet this dependency must be resolved first.
+					resolved.Exists(r => AreResolvable(d, r.Type)) && // There must exist a resolved trait that meets the dependency.
+					!unresolved.Any(u1 => AreResolvable(d, u1.Type))) && // All matching traits that meet this dependency must be resolved first.
+				u.OptionalDependencies.All(d => // To be resolvable, all optional dependencies must be satisfied according to the following condition:
+					!unresolved.Any(u1 => AreResolvable(d, u1.Type)))); // All matching traits that meet this optional dependencies must be resolved first.
 
 			// Continue resolving traits as long as possible.
 			// Each time we resolve some traits, this means dependencies for other traits may then be possible to satisfy in the next pass.
-			while (more.Any())
-				resolved.AddRange(more);
-
-			if (unresolved.Any())
+#pragma warning disable CA1851 // Possible multiple enumerations of 'IEnumerable' collection
+			var readyToResolve = more.ToList();
+			while (readyToResolve.Count != 0)
 			{
-				var exceptionString = "ActorInfo(\"" + Name + "\") failed to initialize because of the following:\r\n";
-				var missing = unresolved.SelectMany(u => u.Dependencies.Where(d => !source.Any(s => testResolve(d, s.Type)))).Distinct();
+				resolved.AddRange(readyToResolve);
+				unresolved.ExceptWith(readyToResolve);
+				readyToResolve.Clear();
+				readyToResolve.AddRange(more);
+			}
+#pragma warning restore CA1851
 
-				exceptionString += "Missing:\r\n";
+			if (unresolved.Count != 0)
+			{
+				var exceptionString = "ActorInfo(\"" + Name + "\") failed to initialize because of the following:\n";
+				var missing = unresolved.SelectMany(u => u.Dependencies.Where(d => !source.Any(s => AreResolvable(d, s.Type)))).Distinct();
+
+				exceptionString += "Missing:\n";
 				foreach (var m in missing)
-					exceptionString += m + " \r\n";
+					exceptionString += m + " \n";
 
-				exceptionString += "Unresolved:\r\n";
+				exceptionString += "Unresolved:\n";
 				foreach (var u in unresolved)
 				{
 					var deps = u.Dependencies.Where(d => !resolved.Exists(r => r.Type == d));
-					exceptionString += u.Type + ": { " + string.Join(", ", deps) + " }\r\n";
+					var optDeps = u.OptionalDependencies.Where(d => !resolved.Exists(r => r.Type == d));
+					var allDeps = string.Join(", ", deps.Select(o => o.ToString()).Concat(optDeps.Select(o => $"[{o}]")));
+					exceptionString += $"{u.Type}: {{ {allDeps} }}\n";
 				}
 
 				throw new YamlException(exceptionString);
 			}
 
-			constructOrderCache = resolved.Select(r => r.Trait).ToList();
+			constructOrderCache = resolved.ConvertAll(r => r.Trait);
 			return constructOrderCache;
 		}
 
@@ -162,10 +175,19 @@ namespace OpenRA
 				.Select(t => t.GetGenericArguments()[0]);
 		}
 
+		public static IEnumerable<Type> OptionalPrerequisitesOf(TraitInfo info)
+		{
+			return info
+				.GetType()
+				.GetInterfaces()
+				.Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(NotBefore<>))
+				.Select(t => t.GetGenericArguments()[0]);
+		}
+
 		public bool HasTraitInfo<T>() where T : ITraitInfoInterface { return traits.Contains<T>(); }
 		public T TraitInfo<T>() where T : ITraitInfoInterface { return traits.Get<T>(); }
 		public T TraitInfoOrDefault<T>() where T : ITraitInfoInterface { return traits.GetOrDefault<T>(); }
-		public IEnumerable<T> TraitInfos<T>() where T : ITraitInfoInterface { return traits.WithInterface<T>(); }
+		public IReadOnlyCollection<T> TraitInfos<T>() where T : ITraitInfoInterface { return traits.WithInterface<T>(); }
 
 		public BitSet<TargetableType> GetAllTargetTypes()
 		{

OpenRA.Game/GameRules/MusicInfo.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -9,7 +9,6 @@
  */
 #endregion
 
-using System.IO;
 using OpenRA.FileSystem;
 
 namespace OpenRA.GameRules
@@ -29,14 +28,14 @@ namespace OpenRA.GameRules
 			Title = value.Value;
 
 			var nd = value.ToDictionary();
-			if (nd.ContainsKey("Hidden"))
-				bool.TryParse(nd["Hidden"].Value, out Hidden);
+			if (nd.TryGetValue("Hidden", out var yaml))
+				bool.TryParse(yaml.Value, out Hidden);
 
-			if (nd.ContainsKey("VolumeModifier"))
-				VolumeModifier = FieldLoader.GetValue<float>("VolumeModifier", nd["VolumeModifier"].Value);
+			if (nd.TryGetValue("VolumeModifier", out yaml))
+				VolumeModifier = FieldLoader.GetValue<float>("VolumeModifier", yaml.Value);
 
-			var ext = nd.ContainsKey("Extension") ? nd["Extension"].Value : "aud";
-			Filename = (nd.ContainsKey("Filename") ? nd["Filename"].Value : key) + "." + ext;
+			var ext = nd.TryGetValue("Extension", out yaml) ? yaml.Value : "aud";
+			Filename = (nd.TryGetValue("Filename", out yaml) ? yaml.Value : key) + "." + ext;
 		}
 
 		public void Load(IReadOnlyFileSystem fileSystem)

OpenRA.Game/GameRules/Ruleset.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,20 +15,18 @@ using System.Linq;
 using System.Threading.Tasks;
 using OpenRA.FileSystem;
 using OpenRA.GameRules;
-using OpenRA.Graphics;
 using OpenRA.Traits;
 
 namespace OpenRA
 {
 	public class Ruleset
 	{
-		public readonly IReadOnlyDictionary<string, ActorInfo> Actors;
+		public readonly ActorInfoDictionary Actors;
 		public readonly IReadOnlyDictionary<string, WeaponInfo> Weapons;
 		public readonly IReadOnlyDictionary<string, SoundInfo> Voices;
 		public readonly IReadOnlyDictionary<string, SoundInfo> Notifications;
 		public readonly IReadOnlyDictionary<string, MusicInfo> Music;
-		public readonly TileSet TileSet;
-		public readonly SequenceProvider Sequences;
+		public readonly ITerrainInfo TerrainInfo;
 		public readonly IReadOnlyDictionary<string, MiniYamlNode> ModelSequences;
 
 		public Ruleset(
@@ -37,17 +35,15 @@ namespace OpenRA
 			IReadOnlyDictionary<string, SoundInfo> voices,
 			IReadOnlyDictionary<string, SoundInfo> notifications,
 			IReadOnlyDictionary<string, MusicInfo> music,
-			TileSet tileSet,
-			SequenceProvider sequences,
+			ITerrainInfo terrainInfo,
 			IReadOnlyDictionary<string, MiniYamlNode> modelSequences)
 		{
-			Actors = actors;
+			Actors = new ActorInfoDictionary(actors);
 			Weapons = weapons;
 			Voices = voices;
 			Notifications = notifications;
 			Music = music;
-			TileSet = tileSet;
-			Sequences = sequences;
+			TerrainInfo = terrainInfo;
 			ModelSequences = modelSequences;
 
 			foreach (var a in Actors.Values)
@@ -60,15 +56,14 @@ namespace OpenRA
 					}
 					catch (YamlException e)
 					{
-						throw new YamlException("Actor type {0}: {1}".F(a.Name, e.Message));
+						throw new YamlException($"Actor type {a.Name}: {e.Message}");
 					}
 				}
 			}
 
 			foreach (var weapon in Weapons)
 			{
-				var projectileLoaded = weapon.Value.Projectile as IRulesetLoaded<WeaponInfo>;
-				if (projectileLoaded != null)
+				if (weapon.Value.Projectile is IRulesetLoaded<WeaponInfo> projectileLoaded)
 				{
 					try
 					{
@@ -76,14 +71,13 @@ namespace OpenRA
 					}
 					catch (YamlException e)
 					{
-						throw new YamlException("Projectile type {0}: {1}".F(weapon.Key, e.Message));
+						throw new YamlException($"Projectile type {weapon.Key}: {e.Message}");
 					}
 				}
 
 				foreach (var warhead in weapon.Value.Warheads)
 				{
-					var cacher = warhead as IRulesetLoaded<WeaponInfo>;
-					if (cacher != null)
+					if (warhead is IRulesetLoaded<WeaponInfo> cacher)
 					{
 						try
 						{
@@ -91,7 +85,7 @@ namespace OpenRA
 						}
 						catch (YamlException e)
 						{
-							throw new YamlException("Weapon type {0}: {1}".F(weapon.Key, e.Message));
+							throw new YamlException($"Weapon type {weapon.Key}: {e.Message}");
 						}
 					}
 				}
@@ -117,7 +111,7 @@ namespace OpenRA
 			if (filterNode != null)
 				yamlNodes = yamlNodes.Where(k => !filterNode(k));
 
-			return new ReadOnlyDictionary<string, T>(yamlNodes.ToDictionaryWithConflictLog(k => k.Key.ToLowerInvariant(), makeObject, "LoadFromManifest<" + name + ">"));
+			return yamlNodes.ToDictionaryWithConflictLog(k => k.Key.ToLowerInvariant(), makeObject, "LoadFromManifest<" + name + ">");
 		}
 
 		public static Ruleset LoadDefaults(ModData modData)
@@ -126,14 +120,14 @@ namespace OpenRA
 			var fs = modData.DefaultFileSystem;
 
 			Ruleset ruleset = null;
-			Action f = () =>
+			void LoadRuleset()
 			{
 				var actors = MergeOrDefault("Manifest,Rules", fs, m.Rules, null, null,
 					k => new ActorInfo(modData.ObjectCreator, k.Key.ToLowerInvariant(), k.Value),
-					filterNode: n => n.Key.StartsWith(ActorInfo.AbstractActorPrefix, StringComparison.Ordinal));
+					filterNode: n => n.Key.StartsWith(ActorInfo.AbstractActorPrefix));
 
 				var weapons = MergeOrDefault("Manifest,Weapons", fs, m.Weapons, null, null,
-					k => new WeaponInfo(k.Key.ToLowerInvariant(), k.Value));
+					k => new WeaponInfo(k.Value));
 
 				var voices = MergeOrDefault("Manifest,Voices", fs, m.Voices, null, null,
 					k => new SoundInfo(k.Value));
@@ -147,15 +141,15 @@ namespace OpenRA
 				var modelSequences = MergeOrDefault("Manifest,ModelSequences", fs, m.ModelSequences, null, null,
 					k => k);
 
-				// The default ruleset does not include a preferred tileset or sequence set
-				ruleset = new Ruleset(actors, weapons, voices, notifications, music, null, null, modelSequences);
-			};
+				// The default ruleset does not include a preferred tileset
+				ruleset = new Ruleset(actors, weapons, voices, notifications, music, null, modelSequences);
+			}
 
 			if (modData.IsOnMainThread)
 			{
 				modData.HandleLoadingProgress();
 
-				var loader = new Task(f);
+				var loader = new Task(LoadRuleset);
 				loader.Start();
 
 				// Animate the loadscreen while we wait
@@ -163,7 +157,7 @@ namespace OpenRA
 					modData.HandleLoadingProgress();
 			}
 			else
-				f();
+				LoadRuleset();
 
 			return ruleset;
 		}
@@ -171,28 +165,27 @@ namespace OpenRA
 		public static Ruleset LoadDefaultsForTileSet(ModData modData, string tileSet)
 		{
 			var dr = modData.DefaultRules;
-			var ts = modData.DefaultTileSets[tileSet];
-			var sequences = modData.DefaultSequences[tileSet];
+			var terrainInfo = modData.DefaultTerrainInfo[tileSet];
 
-			return new Ruleset(dr.Actors, dr.Weapons, dr.Voices, dr.Notifications, dr.Music, ts, sequences, dr.ModelSequences);
+			return new Ruleset(dr.Actors, dr.Weapons, dr.Voices, dr.Notifications, dr.Music, terrainInfo, dr.ModelSequences);
 		}
 
 		public static Ruleset Load(ModData modData, IReadOnlyFileSystem fileSystem, string tileSet,
 			MiniYaml mapRules, MiniYaml mapWeapons, MiniYaml mapVoices, MiniYaml mapNotifications,
-			MiniYaml mapMusic, MiniYaml mapSequences, MiniYaml mapModelSequences)
+			MiniYaml mapMusic, MiniYaml mapModelSequences)
 		{
 			var m = modData.Manifest;
 			var dr = modData.DefaultRules;
 
 			Ruleset ruleset = null;
-			Action f = () =>
+			void LoadRuleset()
 			{
 				var actors = MergeOrDefault("Rules", fileSystem, m.Rules, mapRules, dr.Actors,
 					k => new ActorInfo(modData.ObjectCreator, k.Key.ToLowerInvariant(), k.Value),
-					filterNode: n => n.Key.StartsWith(ActorInfo.AbstractActorPrefix, StringComparison.Ordinal));
+					filterNode: n => n.Key.StartsWith(ActorInfo.AbstractActorPrefix));
 
 				var weapons = MergeOrDefault("Weapons", fileSystem, m.Weapons, mapWeapons, dr.Weapons,
-					k => new WeaponInfo(k.Key.ToLowerInvariant(), k.Value));
+					k => new WeaponInfo(k.Value));
 
 				var voices = MergeOrDefault("Voices", fileSystem, m.Voices, mapVoices, dr.Voices,
 					k => new SoundInfo(k.Value));
@@ -203,26 +196,22 @@ namespace OpenRA
 				var music = MergeOrDefault("Music", fileSystem, m.Music, mapMusic, dr.Music,
 					k => new MusicInfo(k.Key, k.Value));
 
-				// TODO: Add support for merging custom tileset modifications
-				var ts = modData.DefaultTileSets[tileSet];
-
-				// TODO: Top-level dictionary should be moved into the Ruleset instead of in its own object
-				var sequences = mapSequences == null ? modData.DefaultSequences[tileSet] :
-					new SequenceProvider(fileSystem, modData, tileSet, mapSequences);
+				// TODO: Add support for merging custom terrain modifications
+				var terrainInfo = modData.DefaultTerrainInfo[tileSet];
 
 				var modelSequences = dr.ModelSequences;
 				if (mapModelSequences != null)
 					modelSequences = MergeOrDefault("ModelSequences", fileSystem, m.ModelSequences, mapModelSequences, dr.ModelSequences,
 						k => k);
 
-				ruleset = new Ruleset(actors, weapons, voices, notifications, music, ts, sequences, modelSequences);
-			};
+				ruleset = new Ruleset(actors, weapons, voices, notifications, music, terrainInfo, modelSequences);
+			}
 
 			if (modData.IsOnMainThread)
 			{
 				modData.HandleLoadingProgress();
 
-				var loader = new Task(f);
+				var loader = new Task(LoadRuleset);
 				loader.Start();
 
 				// Animate the loadscreen while we wait
@@ -230,17 +219,17 @@ namespace OpenRA
 					modData.HandleLoadingProgress();
 			}
 			else
-				f();
+				LoadRuleset();
 
 			return ruleset;
 		}
 
 		static bool AnyCustomYaml(MiniYaml yaml)
 		{
-			return yaml != null && (yaml.Value != null || yaml.Nodes.Any());
+			return yaml != null && (yaml.Value != null || yaml.Nodes.Length > 0);
 		}
 
-		static bool AnyFlaggedTraits(ModData modData, List<MiniYamlNode> actors)
+		static bool AnyFlaggedTraits(ModData modData, IEnumerable<MiniYamlNode> actors)
 		{
 			foreach (var actorNode in actors)
 			{
@@ -250,12 +239,12 @@ namespace OpenRA
 					{
 						var traitName = traitNode.Key.Split('@')[0];
 						var traitType = modData.ObjectCreator.FindType(traitName + "Info");
-						if (traitType != null && traitType.GetInterface("ILobbyCustomRulesIgnore") == null)
+						if (traitType != null && traitType.GetInterface(nameof(ILobbyCustomRulesIgnore)) == null)
 							return true;
 					}
 					catch (Exception ex)
 					{
-						Log.Write("debug", "Error in AnyFlaggedTraits\r\n" + ex.ToString());
+						Log.Write("debug", "Error in AnyFlaggedTraits\n" + ex.ToString());
 					}
 				}
 			}
@@ -271,18 +260,18 @@ namespace OpenRA
 				return true;
 
 			// Any trait overrides that aren't explicitly whitelisted are flagged
-			if (mapRules != null)
-			{
-				if (AnyFlaggedTraits(modData, mapRules.Nodes))
-					return true;
+			if (mapRules == null)
+				return false;
 
-				if (mapRules.Value != null)
-				{
-					var mapFiles = FieldLoader.GetValue<string[]>("value", mapRules.Value);
-					foreach (var f in mapFiles)
-						if (AnyFlaggedTraits(modData, MiniYaml.FromStream(fileSystem.Open(f), f)))
-							return true;
-				}
+			if (AnyFlaggedTraits(modData, mapRules.Nodes))
+				return true;
+
+			if (mapRules.Value != null)
+			{
+				var mapFiles = FieldLoader.GetValue<string[]>("value", mapRules.Value);
+				foreach (var f in mapFiles)
+					if (AnyFlaggedTraits(modData, MiniYaml.FromStream(fileSystem.Open(f), f)))
+						return true;
 			}
 
 			return false;

OpenRA.Game/GameRules/SoundInfo.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -17,14 +17,14 @@ namespace OpenRA.GameRules
 {
 	public class SoundInfo
 	{
-		public readonly Dictionary<string, string[]> Variants = new Dictionary<string, string[]>();
-		public readonly Dictionary<string, string[]> Prefixes = new Dictionary<string, string[]>();
-		public readonly Dictionary<string, string[]> Voices = new Dictionary<string, string[]>();
-		public readonly Dictionary<string, string[]> Notifications = new Dictionary<string, string[]>();
+		public readonly Dictionary<string, string[]> Variants = new();
+		public readonly Dictionary<string, string[]> Prefixes = new();
+		public readonly Dictionary<string, string[]> Voices = new();
+		public readonly Dictionary<string, string[]> Notifications = new();
 		public readonly string DefaultVariant = ".aud";
 		public readonly string DefaultPrefix = "";
-		public readonly HashSet<string> DisableVariants = new HashSet<string>();
-		public readonly HashSet<string> DisablePrefixes = new HashSet<string>();
+		public readonly HashSet<string> DisableVariants = new();
+		public readonly HashSet<string> DisablePrefixes = new();
 
 		public readonly Lazy<Dictionary<string, SoundPool>> VoicePools;
 		public readonly Lazy<Dictionary<string, SoundPool>> NotificationsPools;
@@ -33,23 +33,28 @@ namespace OpenRA.GameRules
 		{
 			FieldLoader.Load(this, y);
 
-			VoicePools = Exts.Lazy(() => Voices.ToDictionary(a => a.Key, a => new SoundPool(1f, a.Value)));
+			VoicePools = Exts.Lazy(() => Voices.ToDictionary(a => a.Key, a => new SoundPool(1f, SoundPool.DefaultInterruptType, a.Value)));
 			NotificationsPools = Exts.Lazy(() => ParseSoundPool(y, "Notifications"));
 		}
 
-		Dictionary<string, SoundPool> ParseSoundPool(MiniYaml y, string key)
+		static Dictionary<string, SoundPool> ParseSoundPool(MiniYaml y, string key)
 		{
 			var ret = new Dictionary<string, SoundPool>();
-			var classifiction = y.Nodes.First(x => x.Key == key);
+			var classifiction = y.NodeWithKey(key);
 			foreach (var t in classifiction.Value.Nodes)
 			{
 				var volumeModifier = 1f;
-				var volumeModifierNode = t.Value.Nodes.FirstOrDefault(x => x.Key == "VolumeModifier");
+				var volumeModifierNode = t.Value.NodeWithKeyOrDefault(nameof(SoundPool.VolumeModifier));
 				if (volumeModifierNode != null)
 					volumeModifier = FieldLoader.GetValue<float>(volumeModifierNode.Key, volumeModifierNode.Value.Value);
 
+				var interruptType = SoundPool.DefaultInterruptType;
+				var interruptTypeNode = t.Value.NodeWithKeyOrDefault(nameof(SoundPool.InterruptType));
+				if (interruptTypeNode != null)
+					interruptType = FieldLoader.GetValue<SoundPool.InterruptType>(interruptTypeNode.Key, interruptTypeNode.Value.Value);
+
 				var names = FieldLoader.GetValue<string[]>(t.Key, t.Value.Value);
-				var sp = new SoundPool(volumeModifier, names);
+				var sp = new SoundPool(volumeModifier, interruptType, names);
 				ret.Add(t.Key, sp);
 			}
 
@@ -59,13 +64,17 @@ namespace OpenRA.GameRules
 
 	public class SoundPool
 	{
+		public enum InterruptType { DoNotPlay, Interrupt, Overlap }
+		public const InterruptType DefaultInterruptType = InterruptType.DoNotPlay;
 		public readonly float VolumeModifier;
+		public readonly InterruptType Type;
 		readonly string[] clips;
-		readonly List<string> liveclips = new List<string>();
+		readonly List<string> liveclips = new();
 
-		public SoundPool(float volumeModifier, params string[] clips)
+		public SoundPool(float volumeModifier, InterruptType interruptType, params string[] clips)
 		{
 			VolumeModifier = volumeModifier;
+			Type = interruptType;
 			this.clips = clips;
 		}
 

OpenRA.Game/GameRules/WeaponInfo.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -36,7 +36,7 @@ namespace OpenRA.GameRules
 	public class WarheadArgs
 	{
 		public WeaponInfo Weapon;
-		public int[] DamageModifiers = { };
+		public int[] DamageModifiers = Array.Empty<int>();
 		public WPos? Source;
 		public WRot ImpactOrientation;
 		public WPos ImpactPosition;
@@ -99,17 +99,20 @@ namespace OpenRA.GameRules
 		[Desc("Number of shots in a single ammo magazine.")]
 		public readonly int Burst = 1;
 
+		[Desc("Can this weapon target the attacker itself?")]
+		public readonly bool CanTargetSelf = false;
+
 		[Desc("What types of targets are affected.")]
-		public readonly BitSet<TargetableType> ValidTargets = new BitSet<TargetableType>("Ground", "Water");
+		public readonly BitSet<TargetableType> ValidTargets = new("Ground", "Water");
 
 		[Desc("What types of targets are unaffected.", "Overrules ValidTargets.")]
 		public readonly BitSet<TargetableType> InvalidTargets;
 
-		static readonly BitSet<TargetableType> TargetTypeAir = new BitSet<TargetableType>("Air");
+		static readonly BitSet<TargetableType> TargetTypeAir = new("Air");
 
 		[Desc("If weapon is not directly targeting an actor and targeted position is above this altitude,",
 			"the weapon will ignore terrain target types and only check TargetTypeAir for validity.")]
-		public readonly WDist AirThreshold = new WDist(128);
+		public readonly WDist AirThreshold = new(128);
 
 		[Desc("Delay in ticks between firing shots from the same ammo magazine. If one entry, it will be used for all bursts.",
 			"If multiple entries, their number needs to match Burst - 1.")]
@@ -121,25 +124,35 @@ namespace OpenRA.GameRules
 		[Desc("Does this weapon aim at the target's center regardless of other targetable offsets?")]
 		public readonly bool TargetActorCenter = false;
 
-		[FieldLoader.LoadUsing("LoadProjectile")]
+		[FieldLoader.LoadUsing(nameof(LoadProjectile))]
 		public readonly IProjectileInfo Projectile;
 
-		[FieldLoader.LoadUsing("LoadWarheads")]
-		public readonly List<IWarhead> Warheads = new List<IWarhead>();
+		[FieldLoader.LoadUsing(nameof(LoadWarheads))]
+		public readonly List<IWarhead> Warheads = new();
 
-		public WeaponInfo(string name, MiniYaml content)
+		/// <summary>
+		/// This constructor is used solely for documentation generation.
+		/// </summary>
+		public WeaponInfo() { }
+
+		public WeaponInfo(MiniYaml content)
 		{
 			// Resolve any weapon-level yaml inheritance or removals
 			// HACK: The "Defaults" sequence syntax prevents us from doing this generally during yaml parsing
-			content.Nodes = MiniYaml.Merge(new[] { content.Nodes });
+			content = content.WithNodes(MiniYaml.Merge(new IReadOnlyCollection<MiniYamlNode>[] { content.Nodes }));
 			FieldLoader.Load(this, content);
 		}
 
 		static object LoadProjectile(MiniYaml yaml)
 		{
-			if (!yaml.ToDictionary().TryGetValue("Projectile", out var proj))
+			var proj = yaml.NodeWithKeyOrDefault("Projectile")?.Value;
+			if (proj == null)
 				return null;
+
 			var ret = Game.CreateObject<IProjectileInfo>(proj.Value + "Info");
+			if (ret == null)
+				return null;
+
 			FieldLoader.Load(ret, proj);
 			return ret;
 		}
@@ -147,9 +160,12 @@ namespace OpenRA.GameRules
 		static object LoadWarheads(MiniYaml yaml)
 		{
 			var retList = new List<IWarhead>();
-			foreach (var node in yaml.Nodes.Where(n => n.Key.StartsWith("Warhead")))
+			foreach (var node in yaml.Nodes.Where(n => n.Key.StartsWith("Warhead", StringComparison.Ordinal)))
 			{
 				var ret = Game.CreateObject<IWarhead>(node.Value.Value + "Warhead");
+				if (ret == null)
+					continue;
+
 				FieldLoader.Load(ret, node.Value);
 				retList.Add(ret);
 			}
@@ -194,29 +210,24 @@ namespace OpenRA.GameRules
 		/// <summary>Checks if the weapon is valid against (can target) the actor.</summary>
 		public bool IsValidAgainst(Actor victim, Actor firedBy)
 		{
-			var targetTypes = victim.GetEnabledTargetTypes();
-
-			if (!IsValidTarget(targetTypes))
+			if (!CanTargetSelf && victim == firedBy)
 				return false;
 
-			// PERF: Avoid LINQ.
-			foreach (var warhead in Warheads)
-				if (warhead.IsValidAgainst(victim, firedBy))
-					return true;
+			var targetTypes = victim.GetEnabledTargetTypes();
 
-			return false;
+			return IsValidTarget(targetTypes);
 		}
 
 		/// <summary>Checks if the weapon is valid against (can target) the frozen actor.</summary>
 		public bool IsValidAgainst(FrozenActor victim, Actor firedBy)
 		{
-			if (!IsValidTarget(victim.TargetTypes))
+			if (!victim.IsValid)
 				return false;
 
-			if (!Warheads.Any(w => w.IsValidAgainst(victim, firedBy)))
+			if (!CanTargetSelf && victim.Actor == firedBy)
 				return false;
 
-			return true;
+			return IsValidTarget(victim.TargetTypes);
 		}
 
 		/// <summary>Applies all the weapon's warheads to the target.</summary>

OpenRA.Game/GameSpeed.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,22 +15,44 @@ namespace OpenRA
 {
 	public class GameSpeed
 	{
-		[Translate]
-		public readonly string Name = "Default";
-		public readonly int Timestep = 40;
-		public readonly int OrderLatency = 3;
+		[TranslationReference]
+		[FieldLoader.Require]
+		public readonly string Name;
+
+		[FieldLoader.Require]
+		public readonly int Timestep;
+
+		[FieldLoader.Require]
+		public readonly int OrderLatency;
 	}
 
 	public class GameSpeeds : IGlobalModData
 	{
-		[FieldLoader.LoadUsing("LoadSpeeds")]
+		[FieldLoader.Require]
+		public readonly string DefaultSpeed;
+
+		[FieldLoader.LoadUsing(nameof(LoadSpeeds))]
 		public readonly Dictionary<string, GameSpeed> Speeds;
 
 		static object LoadSpeeds(MiniYaml y)
 		{
 			var ret = new Dictionary<string, GameSpeed>();
-			foreach (var node in y.Nodes)
-				ret.Add(node.Key, FieldLoader.Load<GameSpeed>(node.Value));
+			var speedsNode = y.NodeWithKeyOrDefault("Speeds");
+			if (speedsNode == null)
+				throw new YamlException("Error parsing GameSpeeds: Missing Speeds node!");
+
+			foreach (var node in speedsNode.Value.Nodes)
+			{
+				try
+				{
+					ret.Add(node.Key, FieldLoader.Load<GameSpeed>(node.Value));
+				}
+				catch (FieldLoader.MissingFieldsException e)
+				{
+					var label = e.Missing.Length > 1 ? "Required properties missing" : "Required property missing";
+					throw new YamlException($"Error parsing GameSpeed {node.Key}: {label}: {e.Missing.JoinWith(", ")}");
+				}
+			}
 
 			return ret;
 		}

OpenRA.Game/Graphics/Animation.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,7 +22,7 @@ namespace OpenRA.Graphics
 		public string Name { get; private set; }
 		public bool IsDecoration { get; set; }
 
-		readonly SequenceProvider sequenceProvider;
+		readonly SequenceSet sequences;
 		readonly Func<WAngle> facingFunc;
 		readonly Func<bool> paused;
 
@@ -30,7 +30,7 @@ namespace OpenRA.Graphics
 		bool backwards;
 		bool tickAlways;
 		int timeUntilNextFrame;
-		Action tickFunc = () => { };
+		Action tickFunc;
 
 		public Animation(World world, string name)
 			: this(world, name, () => WAngle.Zero) { }
@@ -43,48 +43,57 @@ namespace OpenRA.Graphics
 
 		public Animation(World world, string name, Func<WAngle> facingFunc, Func<bool> paused)
 		{
-			sequenceProvider = world.Map.Rules.Sequences;
+			sequences = world.Map.Sequences;
 			Name = name.ToLowerInvariant();
 			this.facingFunc = facingFunc;
 			this.paused = paused;
 		}
 
-		public int CurrentFrame { get { return backwards ? CurrentSequence.Length - frame - 1 : frame; } }
-		public Sprite Image { get { return CurrentSequence.GetSprite(CurrentFrame, facingFunc()); } }
+		public int CurrentFrame => backwards ? CurrentSequence.Length - frame - 1 : frame;
 
-		public IRenderable[] Render(WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale)
+		public Sprite Image => CurrentSequence.GetSprite(CurrentFrame, facingFunc());
+
+		public IRenderable[] Render(WPos pos, in WVec offset, int zOffset, PaletteReference palette)
 		{
-			var imageRenderable = new SpriteRenderable(Image, pos, offset, CurrentSequence.ZOffset + zOffset, palette, scale, IsDecoration, CurrentSequence.IgnoreWorldTint);
+			var tintModifiers = CurrentSequence.IgnoreWorldTint ? TintModifiers.IgnoreWorldTint : TintModifiers.None;
+			var alpha = CurrentSequence.GetAlpha(CurrentFrame);
+			var (image, rotation) = CurrentSequence.GetSpriteWithRotation(CurrentFrame, facingFunc());
+			var imageRenderable = new SpriteRenderable(image, pos, offset, CurrentSequence.ZOffset + zOffset, palette, CurrentSequence.Scale, alpha, float3.Ones, tintModifiers, IsDecoration,
+				rotation);
 
-			if (CurrentSequence.ShadowStart >= 0)
+			var shadow = CurrentSequence.GetShadow(CurrentFrame, facingFunc());
+			if (shadow != null)
 			{
-				var shadow = CurrentSequence.GetShadow(CurrentFrame, facingFunc());
-				var shadowRenderable = new SpriteRenderable(shadow, pos, offset, CurrentSequence.ShadowZOffset + zOffset, palette, scale, true, CurrentSequence.IgnoreWorldTint);
+				var shadowRenderable = new SpriteRenderable(shadow, pos, offset, CurrentSequence.ShadowZOffset + zOffset, palette, CurrentSequence.Scale, 1f, float3.Ones, tintModifiers,
+					true, rotation);
 				return new IRenderable[] { shadowRenderable, imageRenderable };
 			}
 
 			return new IRenderable[] { imageRenderable };
 		}
 
-		public IRenderable[] RenderUI(WorldRenderer wr, int2 pos, WVec offset, int zOffset, PaletteReference palette, float scale)
+		public IRenderable[] RenderUI(WorldRenderer wr, int2 pos, in WVec offset, int zOffset, PaletteReference palette, float scale = 1f, float rotation = 0f)
 		{
+			scale *= CurrentSequence.Scale;
 			var screenOffset = (scale * wr.ScreenVectorComponents(offset)).XY.ToInt2();
 			var imagePos = pos + screenOffset - new int2((int)(scale * Image.Size.X / 2), (int)(scale * Image.Size.Y / 2));
-			var imageRenderable = new UISpriteRenderable(Image, WPos.Zero + offset, imagePos, CurrentSequence.ZOffset + zOffset, palette, scale);
+			var alpha = CurrentSequence.GetAlpha(CurrentFrame);
+			var imageRenderable = new UISpriteRenderable(Image, WPos.Zero + offset, imagePos, CurrentSequence.ZOffset + zOffset, palette, scale, alpha, rotation);
 
-			if (CurrentSequence.ShadowStart >= 0)
+			var shadow = CurrentSequence.GetShadow(CurrentFrame, facingFunc());
+			if (shadow != null)
 			{
-				var shadow = CurrentSequence.GetShadow(CurrentFrame, facingFunc());
 				var shadowPos = pos - new int2((int)(scale * shadow.Size.X / 2), (int)(scale * shadow.Size.Y / 2));
-				var shadowRenderable = new UISpriteRenderable(shadow, WPos.Zero + offset, shadowPos, CurrentSequence.ShadowZOffset + zOffset, palette, scale);
+				var shadowRenderable = new UISpriteRenderable(shadow, WPos.Zero + offset, shadowPos, CurrentSequence.ShadowZOffset + zOffset, palette, scale, 1f, rotation);
 				return new IRenderable[] { shadowRenderable, imageRenderable };
 			}
 
 			return new IRenderable[] { imageRenderable };
 		}
 
-		public Rectangle ScreenBounds(WorldRenderer wr, WPos pos, WVec offset, float scale)
+		public Rectangle ScreenBounds(WorldRenderer wr, WPos pos, in WVec offset)
 		{
+			var scale = CurrentSequence.Scale;
 			var xy = wr.ScreenPxPosition(pos) + wr.ScreenPxOffset(offset);
 			var cb = CurrentSequence.Bounds;
 			return Rectangle.FromLTRB(
@@ -96,7 +105,7 @@ namespace OpenRA.Graphics
 
 		public IRenderable[] Render(WPos pos, PaletteReference palette)
 		{
-			return Render(pos, WVec.Zero, 0, palette, 1f);
+			return Render(pos, WVec.Zero, 0, palette);
 		}
 
 		public void Play(string sequenceName)
@@ -107,7 +116,7 @@ namespace OpenRA.Graphics
 		int CurrentSequenceTickOrDefault()
 		{
 			const int DefaultTick = 40; // 25 fps == 40 ms
-			return CurrentSequence != null ? CurrentSequence.Tick : DefaultTick;
+			return CurrentSequence?.Tick ?? DefaultTick;
 		}
 
 		void PlaySequence(string sequenceName)
@@ -155,7 +164,7 @@ namespace OpenRA.Graphics
 				if (frame >= CurrentSequence.Length)
 				{
 					frame = CurrentSequence.Length - 1;
-					tickFunc = () => { };
+					tickFunc = null;
 					after?.Invoke();
 				}
 			};
@@ -203,13 +212,13 @@ namespace OpenRA.Graphics
 		public void Tick(int t)
 		{
 			if (tickAlways)
-				tickFunc();
+				tickFunc?.Invoke();
 			else
 			{
 				timeUntilNextFrame -= t;
 				while (timeUntilNextFrame <= 0)
 				{
-					tickFunc();
+					tickFunc?.Invoke();
 					timeUntilNextFrame += CurrentSequenceTickOrDefault();
 				}
 			}
@@ -227,11 +236,11 @@ namespace OpenRA.Graphics
 			}
 		}
 
-		public bool HasSequence(string seq) { return sequenceProvider.HasSequence(Name, seq); }
+		public bool HasSequence(string seq) { return sequences.HasSequence(Name, seq); }
 
 		public ISpriteSequence GetSequence(string sequenceName)
 		{
-			return sequenceProvider.GetSequence(Name, sequenceName);
+			return sequences.GetSequence(Name, sequenceName);
 		}
 
 		public string GetRandomExistingSequence(string[] sequences, MersenneTwister random)

OpenRA.Game/Graphics/AnimationWithOffset.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -35,21 +35,21 @@ namespace OpenRA.Graphics
 			ZOffset = zOffset;
 		}
 
-		public IRenderable[] Render(Actor self, WorldRenderer wr, PaletteReference pal, float scale)
+		public IRenderable[] Render(Actor self, PaletteReference pal)
 		{
 			var center = self.CenterPosition;
-			var offset = OffsetFunc != null ? OffsetFunc() : WVec.Zero;
+			var offset = OffsetFunc?.Invoke() ?? WVec.Zero;
 
-			var z = (ZOffset != null) ? ZOffset(center + offset) : 0;
-			return Animation.Render(center, offset, z, pal, scale);
+			var z = ZOffset?.Invoke(center + offset) ?? 0;
+			return Animation.Render(center, offset, z, pal);
 		}
 
-		public Rectangle ScreenBounds(Actor self, WorldRenderer wr, float scale)
+		public Rectangle ScreenBounds(Actor self, WorldRenderer wr)
 		{
 			var center = self.CenterPosition;
-			var offset = OffsetFunc != null ? OffsetFunc() : WVec.Zero;
+			var offset = OffsetFunc?.Invoke() ?? WVec.Zero;
 
-			return Animation.ScreenBounds(wr, center, offset, scale);
+			return Animation.ScreenBounds(wr, center, offset);
 		}
 
 		public static implicit operator AnimationWithOffset(Animation a)

OpenRA.Game/Graphics/ChromeProvider.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -49,10 +49,10 @@ namespace OpenRA.Graphics
 
 			public readonly int[] PanelRegion = null;
 			public readonly PanelSides PanelSides = PanelSides.All;
-			public readonly Dictionary<string, Rectangle> Regions = new Dictionary<string, Rectangle>();
+			public readonly Dictionary<string, Rectangle> Regions = new();
 		}
 
-		public static IReadOnlyDictionary<string, Collection> Collections { get; private set; }
+		public static IReadOnlyDictionary<string, Collection> Collections => collections;
 		static Dictionary<string, Collection> collections;
 		static Dictionary<string, (Sheet Sheet, int Density)> cachedSheets;
 		static Dictionary<string, Dictionary<string, Sprite>> cachedSprites;
@@ -77,13 +77,12 @@ namespace OpenRA.Graphics
 			cachedPanelSprites = new Dictionary<string, Sprite[]>();
 			cachedCollectionSheets = new Dictionary<Collection, (Sheet, int)>();
 
-			Collections = new ReadOnlyDictionary<string, Collection>(collections);
-
+			var stringPool = new HashSet<string>(); // Reuse common strings in YAML
 			var chrome = MiniYaml.Merge(modData.Manifest.Chrome
-				.Select(s => MiniYaml.FromStream(fileSystem.Open(s), s)));
+				.Select(s => MiniYaml.FromStream(fileSystem.Open(s), s, stringPool: stringPool)));
 
 			foreach (var c in chrome)
-				if (!c.Key.StartsWith("^", StringComparison.Ordinal))
+				if (!c.Key.StartsWith('^'))
 					LoadCollection(c.Key, c.Value);
 		}
 
@@ -102,9 +101,7 @@ namespace OpenRA.Graphics
 
 		static void LoadCollection(string name, MiniYaml yaml)
 		{
-			if (Game.ModData.LoadScreen != null)
-				Game.ModData.LoadScreen.Display();
-
+			Game.ModData.LoadScreen?.Display();
 			collections.Add(name, FieldLoader.Load<Collection>(yaml));
 		}
 
@@ -146,6 +143,15 @@ namespace OpenRA.Graphics
 		}
 
 		public static Sprite GetImage(string collectionName, string imageName)
+		{
+			var image = TryGetImage(collectionName, imageName);
+			if (image == null)
+				throw new ArgumentException($"Sprite `{collectionName}/{imageName}` was not found.");
+
+			return image;
+		}
+
+		public static Sprite TryGetImage(string collectionName, string imageName)
 		{
 			if (string.IsNullOrEmpty(collectionName))
 				return null;
@@ -155,10 +161,7 @@ namespace OpenRA.Graphics
 				return sprite;
 
 			if (!collections.TryGetValue(collectionName, out var collection))
-			{
-				Log.Write("debug", "Could not find collection '{0}'", collectionName);
 				return null;
-			}
 
 			if (!collection.Regions.TryGetValue(imageName, out var mi))
 				return null;
@@ -178,6 +181,15 @@ namespace OpenRA.Graphics
 		}
 
 		public static Sprite[] GetPanelImages(string collectionName)
+		{
+			var panel = TryGetPanelImages(collectionName);
+			if (panel == null)
+				throw new ArgumentException($"Panel `{collectionName}` was not found.");
+
+			return panel;
+		}
+
+		public static Sprite[] TryGetPanelImages(string collectionName)
 		{
 			if (string.IsNullOrEmpty(collectionName))
 				return null;
@@ -187,17 +199,14 @@ namespace OpenRA.Graphics
 				return cachedSprites;
 
 			if (!collections.TryGetValue(collectionName, out var collection))
-			{
-				Log.Write("debug", "Could not find collection '{0}'", collectionName);
 				return null;
-			}
 
 			Sprite[] sprites;
 			if (collection.PanelRegion != null)
 			{
 				if (collection.PanelRegion.Length != 8)
 				{
-					Log.Write("debug", "Collection '{0}' does not define a valid PanelRegion", collectionName);
+					Log.Write("debug", $"Collection '{collectionName}' does not define a valid PanelRegion");
 					return null;
 				}
 
@@ -224,18 +233,23 @@ namespace OpenRA.Graphics
 			}
 			else
 			{
+				// PERF: We don't need to search for images if there are no definitions.
+				// PERF: It's more efficient to send an empty array rather than an array of 9 nulls.
+				if (collection.Regions.Count == 0)
+					return Array.Empty<Sprite>();
+
 				// Support manual definitions for unusual dialog layouts
 				sprites = new[]
 				{
-					GetImage(collectionName, "corner-tl"),
-					GetImage(collectionName, "border-t"),
-					GetImage(collectionName, "corner-tr"),
-					GetImage(collectionName, "border-l"),
-					GetImage(collectionName, "background"),
-					GetImage(collectionName, "border-r"),
-					GetImage(collectionName, "corner-bl"),
-					GetImage(collectionName, "border-b"),
-					GetImage(collectionName, "corner-br")
+					TryGetImage(collectionName, "corner-tl"),
+					TryGetImage(collectionName, "border-t"),
+					TryGetImage(collectionName, "corner-tr"),
+					TryGetImage(collectionName, "border-l"),
+					TryGetImage(collectionName, "background"),
+					TryGetImage(collectionName, "border-r"),
+					TryGetImage(collectionName, "corner-bl"),
+					TryGetImage(collectionName, "border-b"),
+					TryGetImage(collectionName, "corner-br")
 				};
 			}
 
@@ -250,13 +264,13 @@ namespace OpenRA.Graphics
 
 			if (!collections.TryGetValue(collectionName, out var collection))
 			{
-				Log.Write("debug", "Could not find collection '{0}'", collectionName);
+				Log.Write("debug", $"Could not find collection '{collectionName}'");
 				return new Size(0, 0);
 			}
 
 			if (collection.PanelRegion == null || collection.PanelRegion.Length != 8)
 			{
-				Log.Write("debug", "Collection '{0}' does not define a valid PanelRegion", collectionName);
+				Log.Write("debug", $"Collection '{collectionName}' does not define a valid PanelRegion");
 				return new Size(0, 0);
 			}
 

OpenRA.Game/Graphics/CursorManager.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -17,7 +17,7 @@ namespace OpenRA.Graphics
 {
 	public sealed class CursorManager
 	{
-		class Cursor
+		sealed class Cursor
 		{
 			public string Name;
 			public int2 PaddedSize;
@@ -28,14 +28,14 @@ namespace OpenRA.Graphics
 			public IHardwareCursor[] Cursors;
 		}
 
-		readonly Dictionary<string, Cursor> cursors = new Dictionary<string, Cursor>();
+		readonly Dictionary<string, Cursor> cursors = new();
 		readonly SheetBuilder sheetBuilder;
 		readonly GraphicSettings graphicSettings;
 
 		Cursor cursor;
 		bool isLocked = false;
 		int2 lockedPosition;
-		bool hardwareCursorsDisabled = false;
+		readonly bool hardwareCursorsDisabled = false;
 		bool hardwareCursorsDoubled = false;
 
 		public CursorManager(CursorProvider cursorProvider)
@@ -69,9 +69,16 @@ namespace OpenRA.Graphics
 					// Hotspot is specified relative to the center of the frame
 					var hotspot = f.Offset.ToInt2() - kv.Value.Hotspot - new int2(f.Size) / 2;
 
-					// SheetBuilder expects data in BGRA
-					var data = FrameToBGRA(kv.Key, f, palette);
-					c.Sprites[c.Length++] = sheetBuilder.Add(data, f.Size, 0, hotspot);
+					// Resolve indexed data to real colours
+					var data = f.Data;
+					var type = f.Type;
+					if (type == SpriteFrameType.Indexed8)
+					{
+						data = ConvertIndexedToBgra(kv.Key, f, palette);
+						type = SpriteFrameType.Bgra32;
+					}
+
+					c.Sprites[c.Length++] = sheetBuilder.Add(data, type, f.Size, 0, hotspot);
 
 					// Bounds relative to the hotspot
 					c.Bounds = Rectangle.Union(c.Bounds, new Rectangle(hotspot, f.Size));
@@ -99,34 +106,27 @@ namespace OpenRA.Graphics
 			// Dispose any existing cursors to avoid leaking native resources
 			ClearHardwareCursors();
 
-			try
+			foreach (var kv in cursors)
 			{
-				foreach (var kv in cursors)
+				var template = kv.Value;
+				for (var i = 0; i < template.Sprites.Length; i++)
 				{
-					var template = kv.Value;
-					for (var i = 0; i < template.Sprites.Length; i++)
+					template.Cursors[i]?.Dispose();
+
+					// Calculate the padding to position the frame within sequenceBounds
+					var paddingTL = -(template.Bounds.Location - template.Sprites[i].Offset.XY.ToInt2());
+					var paddingBR = template.PaddedSize - new int2(template.Sprites[i].Bounds.Size) - paddingTL;
+
+					var hardwareCursor = CreateHardwareCursor(kv.Key, template.Sprites[i], paddingTL, paddingBR, -template.Bounds.Location);
+					if (hardwareCursor != null)
+						template.Cursors[i] = hardwareCursor;
+					else
 					{
-						if (template.Cursors[i] != null)
-							template.Cursors[i].Dispose();
-
-						// Calculate the padding to position the frame within sequenceBounds
-						var paddingTL = -(template.Bounds.Location - template.Sprites[i].Offset.XY.ToInt2());
-						var paddingBR = template.PaddedSize - new int2(template.Sprites[i].Bounds.Size) - paddingTL;
-
-						template.Cursors[i] = CreateHardwareCursor(kv.Key, template.Sprites[i], paddingTL, paddingBR, -template.Bounds.Location);
+						Log.Write("debug", $"Failed to initialize hardware cursor for {template.Name}.");
+						Console.WriteLine($"Failed to initialize hardware cursor for {template.Name}.");
 					}
 				}
 			}
-			catch (Exception e)
-			{
-				Log.Write("debug", "Failed to initialize hardware cursors. Falling back to software cursors.");
-				Log.Write("debug", "Error was: " + e.Message);
-
-				Console.WriteLine("Failed to initialize hardware cursors. Falling back to software cursors.");
-				Console.WriteLine("Error was: " + e.Message);
-
-				ClearHardwareCursors();
-			}
 
 			hardwareCursorsDoubled = graphicSettings.CursorDouble;
 		}
@@ -170,10 +170,11 @@ namespace OpenRA.Graphics
 			if (cursor != null && frame >= cursor.Cursors.Length)
 				frame %= cursor.Cursors.Length;
 
-			if (cursor == null || isLocked)
+			var hardwareCursor = cursor?.Cursors[frame];
+			if (hardwareCursor == null || isLocked)
 				Game.Renderer.Window.SetHardwareCursor(null);
 			else
-				Game.Renderer.Window.SetHardwareCursor(cursor.Cursors[frame]);
+				Game.Renderer.Window.SetHardwareCursor(hardwareCursor);
 		}
 
 		public void Render(Renderer renderer)
@@ -189,17 +190,17 @@ namespace OpenRA.Graphics
 			// Render cursor in software
 			var doubleCursor = graphicSettings.CursorDouble;
 			var cursorSprite = cursor.Sprites[frame % cursor.Length];
-			var cursorSize = doubleCursor ? 2.0f * cursorSprite.Size : cursorSprite.Size;
+			var cursorScale = doubleCursor ? 2 : 1;
 
 			// Cursor is rendered in native window coordinates
 			// Apply same scaling rules as hardware cursors
 			if (Game.Renderer.NativeWindowScale > 1.5f)
-				cursorSize = 2 * cursorSize;
+				cursorScale *= 2;
 
 			var mousePos = isLocked ? lockedPosition : Viewport.LastMousePos;
 			renderer.RgbaSpriteRenderer.DrawSprite(cursorSprite,
 				mousePos,
-				cursorSize / Game.Renderer.WindowScale);
+				cursorScale / Game.Renderer.WindowScale);
 		}
 
 		public void Lock()
@@ -217,33 +218,27 @@ namespace OpenRA.Graphics
 			Update();
 		}
 
-		public static byte[] FrameToBGRA(string name, ISpriteFrame frame, ImmutablePalette palette)
+		public static byte[] ConvertIndexedToBgra(string name, ISpriteFrame frame, ImmutablePalette palette)
 		{
-			// Data is already in BGRA format
-			if (frame.Type == SpriteFrameType.BGRA)
-				return frame.Data;
+			if (frame.Type != SpriteFrameType.Indexed8)
+				throw new ArgumentException("ConvertIndexedToBgra requires input frames to be indexed.", nameof(frame));
 
-			// Cursors may be either native BGRA or Indexed.
-			// Indexed sprites are converted to BGRA using the referenced palette.
 			// All palettes must be explicitly referenced, even if they are embedded in the sprite.
-			if (frame.Type == SpriteFrameType.Indexed && palette == null)
-				throw new InvalidOperationException("Cursor sequence `{0}` attempted to load an indexed sprite but does not define Palette".F(name));
+			if (palette == null)
+				throw new InvalidOperationException($"Cursor sequence `{name}` attempted to load an indexed sprite but does not define Palette");
 
 			var width = frame.Size.Width;
 			var height = frame.Size.Height;
 			var data = new byte[4 * width * height];
-			for (var j = 0; j < height; j++)
+			unsafe
 			{
-				for (var i = 0; i < width; i++)
+				// Cast the data to an int array so we can copy the src data directly
+				fixed (byte* bd = &data[0])
 				{
-					var rgba = palette[frame.Data[j * width + i]];
-					var k = 4 * (j * width + i);
-
-					// Convert RGBA to BGRA
-					data[k] = (byte)(rgba >> 16);
-					data[k + 1] = (byte)(rgba >> 8);
-					data[k + 2] = (byte)(rgba >> 0);
-					data[k + 3] = (byte)(rgba >> 24);
+					var rgba = (uint*)bd;
+					for (var j = 0; j < height; j++)
+						for (var i = 0; i < width; i++)
+							rgba[j * width + i] = palette[frame.Data[j * width + i]];
 				}
 			}
 

OpenRA.Game/Graphics/CursorProvider.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -24,30 +24,30 @@ namespace OpenRA.Graphics
 		public CursorProvider(ModData modData)
 		{
 			var fileSystem = modData.DefaultFileSystem;
+			var stringPool = new HashSet<string>(); // Reuse common strings in YAML
 			var sequenceYaml = MiniYaml.Merge(modData.Manifest.Cursors.Select(
-				s => MiniYaml.FromStream(fileSystem.Open(s), s)));
+				s => MiniYaml.FromStream(fileSystem.Open(s), s, stringPool: stringPool)));
 
-			var nodesDict = new MiniYaml(null, sequenceYaml).ToDictionary();
+			var cursorsYaml = new MiniYaml(null, sequenceYaml).NodeWithKey("Cursors").Value;
 
 			// Overwrite previous definitions if there are duplicates
 			var pals = new Dictionary<string, IProvidesCursorPaletteInfo>();
-			foreach (var p in modData.DefaultRules.Actors["world"].TraitInfos<IProvidesCursorPaletteInfo>())
+			foreach (var p in modData.DefaultRules.Actors[SystemActors.World].TraitInfos<IProvidesCursorPaletteInfo>())
 				if (p.Palette != null)
 					pals[p.Palette] = p;
 
-			Palettes = nodesDict["Cursors"].Nodes.Select(n => n.Value.Value)
+			Palettes = cursorsYaml.Nodes.Select(n => n.Value.Value)
 				.Where(p => p != null)
 				.Distinct()
-				.ToDictionary(p => p, p => pals[p].ReadPalette(modData.DefaultFileSystem))
-				.AsReadOnly();
+				.ToDictionary(p => p, p => pals[p].ReadPalette(modData.DefaultFileSystem));
 
 			var frameCache = new FrameCache(fileSystem, modData.SpriteLoaders);
 			var cursors = new Dictionary<string, CursorSequence>();
-			foreach (var s in nodesDict["Cursors"].Nodes)
+			foreach (var s in cursorsYaml.Nodes)
 				foreach (var sequence in s.Value.Nodes)
 					cursors.Add(sequence.Key, new CursorSequence(frameCache, sequence.Key, s.Key, s.Value.Value, sequence.Value));
 
-			Cursors = cursors.AsReadOnly();
+			Cursors = cursors;
 		}
 
 		public bool HasCursorSequence(string cursor)
@@ -60,7 +60,7 @@ namespace OpenRA.Graphics
 			try { return Cursors[cursor]; }
 			catch (KeyNotFoundException)
 			{
-				throw new InvalidOperationException("Cursor does not have a sequence `{0}`".F(cursor));
+				throw new InvalidOperationException($"Cursor does not have a sequence `{cursor}`");
 			}
 		}
 	}

OpenRA.Game/Graphics/CursorSequence.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -27,32 +27,40 @@ namespace OpenRA.Graphics
 		{
 			var d = info.ToDictionary();
 
-			Start = Exts.ParseIntegerInvariant(d["Start"].Value);
+			Start = Exts.ParseInt32Invariant(d["Start"].Value);
 			Palette = palette;
 			Name = name;
 
-			Frames = cache[cursorSrc].Skip(Start).ToArray();
+			var cursorSprites = cache[cursorSrc];
+			Frames = cursorSprites.Skip(Start).ToArray();
 
-			if ((d.ContainsKey("Length") && d["Length"].Value == "*") || (d.ContainsKey("End") && d["End"].Value == "*"))
+			if ((d.TryGetValue("Length", out var yaml) && yaml.Value == "*") ||
+				(d.TryGetValue("End", out yaml) && yaml.Value == "*"))
 				Length = Frames.Length;
-			else if (d.ContainsKey("Length"))
-				Length = Exts.ParseIntegerInvariant(d["Length"].Value);
-			else if (d.ContainsKey("End"))
-				Length = Exts.ParseIntegerInvariant(d["End"].Value) - Start;
+			else if (d.TryGetValue("Length", out yaml))
+				Length = Exts.ParseInt32Invariant(yaml.Value);
+			else if (d.TryGetValue("End", out yaml))
+				Length = Exts.ParseInt32Invariant(yaml.Value) - Start;
 			else
 				Length = 1;
 
 			Frames = Frames.Take(Length).ToArray();
 
-			if (d.ContainsKey("X"))
+			if (Start > cursorSprites.Length)
+				throw new YamlException($"Cursor {name}: {nameof(Start)} is greater than the length of the sprite sequence.");
+
+			if (Length > cursorSprites.Length)
+				throw new YamlException($"Cursor {name}: {nameof(Length)} is greater than the length of the sprite sequence.");
+
+			if (d.TryGetValue("X", out yaml))
 			{
-				Exts.TryParseIntegerInvariant(d["X"].Value, out var x);
+				Exts.TryParseInt32Invariant(yaml.Value, out var x);
 				Hotspot = Hotspot.WithX(x);
 			}
 
-			if (d.ContainsKey("Y"))
+			if (d.TryGetValue("Y", out yaml))
 			{
-				Exts.TryParseIntegerInvariant(d["Y"].Value, out var y);
+				Exts.TryParseInt32Invariant(yaml.Value, out var y);
 				Hotspot = Hotspot.WithY(y);
 			}
 		}

OpenRA.Game/Graphics/HardwarePalette.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -17,73 +17,98 @@ namespace OpenRA.Graphics
 {
 	public sealed class HardwarePalette : IDisposable
 	{
-		public ITexture Texture { get; private set; }
+		public ITexture Texture { get; }
+		public ITexture ColorShifts { get; }
+
 		public int Height { get; private set; }
-		readonly Dictionary<string, ImmutablePalette> palettes = new Dictionary<string, ImmutablePalette>();
-		readonly Dictionary<string, MutablePalette> modifiablePalettes = new Dictionary<string, MutablePalette>();
-		readonly IReadOnlyDictionary<string, MutablePalette> readOnlyModifiablePalettes;
-		readonly Dictionary<string, int> indices = new Dictionary<string, int>();
-		byte[] buffer = new byte[0];
+		readonly Dictionary<string, ImmutablePalette> palettes = new();
+		readonly Dictionary<string, MutablePalette> mutablePalettes = new();
+		readonly Dictionary<string, int> indices = new();
+		byte[] buffer = Array.Empty<byte>();
+		float[] colorShiftBuffer = Array.Empty<float>();
 
 		public HardwarePalette()
 		{
 			Texture = Game.Renderer.Context.CreateTexture();
-			readOnlyModifiablePalettes = modifiablePalettes.AsReadOnly();
+			ColorShifts = Game.Renderer.Context.CreateTexture();
 		}
 
 		public bool Contains(string name)
 		{
-			return modifiablePalettes.ContainsKey(name) || palettes.ContainsKey(name);
+			return mutablePalettes.ContainsKey(name) || palettes.ContainsKey(name);
 		}
 
 		public IPalette GetPalette(string name)
 		{
-			if (modifiablePalettes.TryGetValue(name, out var mutable))
+			if (mutablePalettes.TryGetValue(name, out var mutable))
 				return mutable.AsReadOnly();
 			if (palettes.TryGetValue(name, out var immutable))
 				return immutable;
-			throw new InvalidOperationException("Palette `{0}` does not exist".F(name));
+			throw new InvalidOperationException($"Palette `{name}` does not exist");
 		}
 
 		public int GetPaletteIndex(string name)
 		{
 			if (!indices.TryGetValue(name, out var ret))
-				throw new InvalidOperationException("Palette `{0}` does not exist".F(name));
+				throw new InvalidOperationException($"Palette `{name}` does not exist");
 			return ret;
 		}
 
 		public void AddPalette(string name, ImmutablePalette p, bool allowModifiers)
 		{
 			if (palettes.ContainsKey(name))
-				throw new InvalidOperationException("Palette {0} has already been defined".F(name));
+				throw new InvalidOperationException($"Palette {name} has already been defined");
 
-			int index = palettes.Count;
+			// PERF: the first row in the palette textures is reserved as a placeholder for non-indexed sprites
+			// that do not have a color-shift applied. This provides a quick shortcut to avoid querying the
+			// color-shift texture for every pixel only to find that most are not shifted.
+			var index = palettes.Count + 1;
 			indices.Add(name, index);
 			palettes.Add(name, p);
 
-			if (palettes.Count > Height)
+			if (index >= Height)
 			{
-				Height = Exts.NextPowerOf2(palettes.Count);
+				Height = Exts.NextPowerOf2(index + 1);
 				Array.Resize(ref buffer, Height * Palette.Size * 4);
+				Array.Resize(ref colorShiftBuffer, Height * 8);
 			}
 
 			if (allowModifiers)
-				modifiablePalettes.Add(name, new MutablePalette(p));
+				mutablePalettes.Add(name, new MutablePalette(p));
 			else
 				CopyPaletteToBuffer(index, p);
 		}
 
+		[System.Diagnostics.CodeAnalysis.SuppressMessage(
+			"Performance", "CA1854:Prefer the 'IDictionary.TryGetValue(TKey, out TValue)' method",
+			Justification = "False positive - indexer is a set not a get.")]
 		public void ReplacePalette(string name, IPalette p)
 		{
-			if (modifiablePalettes.ContainsKey(name))
-				CopyPaletteToBuffer(indices[name], modifiablePalettes[name] = new MutablePalette(p));
+			if (mutablePalettes.ContainsKey(name))
+				CopyPaletteToBuffer(indices[name], mutablePalettes[name] = new MutablePalette(p));
 			else if (palettes.ContainsKey(name))
 				CopyPaletteToBuffer(indices[name], palettes[name] = new ImmutablePalette(p));
 			else
-				throw new InvalidOperationException("Palette `{0}` does not exist".F(name));
+				throw new InvalidOperationException($"Palette `{name}` does not exist");
 			CopyBufferToTexture();
 		}
 
+		public void SetColorShift(string name, float hueOffset, float satOffset, float valueMultiplier, float minHue, float maxHue)
+		{
+			var index = GetPaletteIndex(name);
+			colorShiftBuffer[8 * index + 0] = minHue;
+			colorShiftBuffer[8 * index + 1] = maxHue;
+			colorShiftBuffer[8 * index + 4] = hueOffset;
+			colorShiftBuffer[8 * index + 5] = satOffset;
+			colorShiftBuffer[8 * index + 6] = valueMultiplier;
+		}
+
+		public bool HasColorShift(string name)
+		{
+			var index = GetPaletteIndex(name);
+			return colorShiftBuffer[8 * index] != 0 || colorShiftBuffer[8 * index + 1] != 0;
+		}
+
 		public void Initialize()
 		{
 			CopyModifiablePalettesToBuffer();
@@ -97,26 +122,27 @@ namespace OpenRA.Graphics
 
 		void CopyModifiablePalettesToBuffer()
 		{
-			foreach (var kvp in modifiablePalettes)
+			foreach (var kvp in mutablePalettes)
 				CopyPaletteToBuffer(indices[kvp.Key], kvp.Value);
 		}
 
 		void CopyBufferToTexture()
 		{
 			Texture.SetData(buffer, Palette.Size, Height);
+			ColorShifts.SetFloatData(colorShiftBuffer, 2, Height);
 		}
 
 		public void ApplyModifiers(IEnumerable<IPaletteModifier> paletteMods)
 		{
 			foreach (var mod in paletteMods)
-				mod.AdjustPalette(readOnlyModifiablePalettes);
+				mod.AdjustPalette(mutablePalettes);
 
 			// Update our texture with the changes.
 			CopyModifiablePalettesToBuffer();
 			CopyBufferToTexture();
 
 			// Reset modified palettes back to their original colors, ready for next time.
-			foreach (var kvp in modifiablePalettes)
+			foreach (var kvp in mutablePalettes)
 			{
 				var originalPalette = palettes[kvp.Key];
 				var modifiedPalette = kvp.Value;
@@ -127,6 +153,7 @@ namespace OpenRA.Graphics
 		public void Dispose()
 		{
 			Texture.Dispose();
+			ColorShifts.Dispose();
 		}
 	}
 }

OpenRA.Game/Graphics/MarkerTileRenderable.cs

@@ -0,0 +1,56 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Linq;
+using OpenRA.Primitives;
+
+namespace OpenRA.Graphics
+{
+	public class MarkerTileRenderable : IRenderable, IFinalizedRenderable
+	{
+		readonly CPos pos;
+		readonly Color color;
+
+		public MarkerTileRenderable(CPos pos, Color color)
+		{
+			this.pos = pos;
+			this.color = color;
+		}
+
+		public WPos Pos => WPos.Zero;
+		public int ZOffset => 0;
+		public bool IsDecoration => true;
+
+		public IRenderable WithZOffset(int newOffset) { return this; }
+
+		public IRenderable OffsetBy(in WVec vec)
+		{
+			return new MarkerTileRenderable(pos, color);
+		}
+
+		public IRenderable AsDecoration() { return this; }
+
+		public IFinalizedRenderable PrepareRender(WorldRenderer wr) { return this; }
+		public void Render(WorldRenderer wr)
+		{
+			var map = wr.World.Map;
+			var r = map.Grid.Ramps[map.Ramp[pos]];
+			var wpos = map.CenterOfCell(pos) - new WVec(0, 0, r.CenterHeightOffset);
+
+			var corners = r.Corners.Select(corner => wr.Viewport.WorldToViewPx(wr.Screen3DPosition(wpos + corner))).ToList();
+
+			Game.Renderer.RgbaColorRenderer.FillRect(corners[0], corners[1], corners[2], corners[3], color);
+		}
+
+		public void RenderDebugGeometry(WorldRenderer wr) { }
+		public Rectangle ScreenBounds(WorldRenderer wr) { return Rectangle.Empty; }
+	}
+}

OpenRA.Game/Graphics/Model.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,8 +10,8 @@
 #endregion
 
 using System;
-using OpenRA.FileSystem;
 using OpenRA.Primitives;
+using OpenRA.Traits;
 
 namespace OpenRA.Graphics
 {
@@ -25,11 +25,19 @@ namespace OpenRA.Graphics
 		float[] Bounds(uint frame);
 		ModelRenderData RenderData(uint section);
 
-		/// <summary>Returns the smallest rectangle that covers all rotations of all frames in a model</summary>
+		/// <summary>Returns the smallest rectangle that covers all rotations of all frames in a model.</summary>
 		Rectangle AggregateBounds { get; }
 	}
 
-	public struct ModelRenderData
+	public interface IModelWidget
+	{
+		public string Palette { get; }
+		public float Scale { get; }
+		public void Setup(Func<bool> isVisible, Func<string> getPalette, Func<string> getPlayerPalette,
+			Func<float> getScale, Func<IModel> getVoxel, Func<WRot> getRotation);
+	}
+
+	public readonly struct ModelRenderData
 	{
 		public readonly int Start;
 		public readonly int Count;
@@ -43,45 +51,13 @@ namespace OpenRA.Graphics
 		}
 	}
 
-	public interface IModelCache : IDisposable
+	public interface IModelCacheInfo : ITraitInfoInterface { }
+
+	public interface IModelCache
 	{
+		IModel GetModel(string model);
 		IModel GetModelSequence(string model, string sequence);
 		bool HasModelSequence(string model, string sequence);
-		IVertexBuffer<Vertex> VertexBuffer { get; }
-	}
-
-	public interface IModelSequenceLoader
-	{
-		Action<string> OnMissingModelError { get; set; }
-		IModelCache CacheModels(IReadOnlyFileSystem fileSystem, ModData modData, IReadOnlyDictionary<string, MiniYamlNode> modelDefinitions);
-	}
-
-	public class PlaceholderModelSequenceLoader : IModelSequenceLoader
-	{
-		public Action<string> OnMissingModelError { get; set; }
-
-		class PlaceholderModelCache : IModelCache
-		{
-			public IVertexBuffer<Vertex> VertexBuffer { get { throw new NotImplementedException(); } }
-
-			public void Dispose() { }
-
-			public IModel GetModelSequence(string model, string sequence)
-			{
-				throw new NotImplementedException();
-			}
-
-			public bool HasModelSequence(string model, string sequence)
-			{
-				throw new NotImplementedException();
-			}
-		}
-
-		public PlaceholderModelSequenceLoader(ModData modData) { }
-
-		public IModelCache CacheModels(IReadOnlyFileSystem fileSystem, ModData modData, IReadOnlyDictionary<string, MiniYamlNode> modelDefinitions)
-		{
-			return new PlaceholderModelCache();
-		}
+		IVertexBuffer<ModelVertex> VertexBuffer { get; }
 	}
 }

OpenRA.Game/Graphics/ModelAnimation.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -14,7 +14,7 @@ using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
-	public struct ModelAnimation
+	public readonly struct ModelAnimation
 	{
 		public readonly IModel Model;
 		public readonly Func<WVec> OffsetFunc;
@@ -46,12 +46,6 @@ namespace OpenRA.Graphics
 				xy.Y + (int)(r.Bottom * scale));
 		}
 
-		public bool IsVisible
-		{
-			get
-			{
-				return DisableFunc == null || !DisableFunc();
-			}
-		}
+		public bool IsVisible => DisableFunc == null || !DisableFunc();
 	}
 }

OpenRA.Game/Graphics/ModelVertex.cs

@@ -0,0 +1,53 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Runtime.InteropServices;
+
+namespace OpenRA.Graphics
+{
+	[StructLayout(LayoutKind.Sequential)]
+	public readonly struct ModelVertex
+	{
+		// 3d position
+		public readonly float X, Y, Z;
+
+		// Primary and secondary texture coordinates or RGBA color
+		public readonly float S, T, U, V;
+
+		// Palette and channel flags
+		public readonly float P, C;
+
+		public ModelVertex(in float3 xyz, float s, float t, float u, float v, float p, float c)
+			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, p, c) { }
+
+		public ModelVertex(float x, float y, float z, float s, float t, float u, float v, float p, float c)
+		{
+			X = x; Y = y; Z = z;
+			S = s; T = t;
+			U = u; V = v;
+			P = p; C = c;
+		}
+	}
+
+	public sealed class ModelShaderBindings : ShaderBindings
+	{
+		public ModelShaderBindings()
+			: base("model")
+		{ }
+
+		public override ShaderVertexAttribute[] Attributes { get; } = new[]
+		{
+			new ShaderVertexAttribute("aVertexPosition", ShaderVertexAttributeType.Float, 3, 0),
+			new ShaderVertexAttribute("aVertexTexCoord", ShaderVertexAttributeType.Float, 4, 12),
+			new ShaderVertexAttribute("aVertexTexMetadata", ShaderVertexAttributeType.Float, 2, 28),
+		};
+	}
+}

OpenRA.Game/Graphics/Palette.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -30,7 +30,7 @@ namespace OpenRA.Graphics
 
 		public static Color GetColor(this IPalette palette, int index)
 		{
-			return Color.FromArgb((int)palette[index]);
+			return Color.FromArgb(palette[index]);
 		}
 
 		public static IPalette AsReadOnly(this IPalette palette)
@@ -40,11 +40,12 @@ namespace OpenRA.Graphics
 			return new ReadOnlyPalette(palette);
 		}
 
-		class ReadOnlyPalette : IPalette
+		sealed class ReadOnlyPalette : IPalette
 		{
-			IPalette palette;
+			readonly IPalette palette;
 			public ReadOnlyPalette(IPalette palette) { this.palette = palette; }
-			public uint this[int index] { get { return palette[index]; } }
+			public uint this[int index] => palette[index];
+
 			public void CopyToArray(Array destination, int destinationOffset)
 			{
 				palette.CopyToArray(destination, destinationOffset);
@@ -56,28 +57,25 @@ namespace OpenRA.Graphics
 	{
 		readonly uint[] colors = new uint[Palette.Size];
 
-		public uint this[int index]
-		{
-			get { return colors[index]; }
-		}
+		public uint this[int index] => colors[index];
 
 		public void CopyToArray(Array destination, int destinationOffset)
 		{
 			Buffer.BlockCopy(colors, 0, destination, destinationOffset * 4, Palette.Size * 4);
 		}
 
-		public ImmutablePalette(string filename, int[] remap)
+		public ImmutablePalette(string filename, int[] remapTransparent, int[] remap)
 		{
 			using (var s = File.OpenRead(filename))
-				LoadFromStream(s, remap);
+				LoadFromStream(s, remapTransparent, remap);
 		}
 
-		public ImmutablePalette(Stream s, int[] remapShadow)
+		public ImmutablePalette(Stream s, int[] remapTransparent, int[] remapShadow)
 		{
-			LoadFromStream(s, remapShadow);
+			LoadFromStream(s, remapTransparent, remapShadow);
 		}
 
-		void LoadFromStream(Stream s, int[] remapShadow)
+		void LoadFromStream(Stream s, int[] remapTransparent, int[] remapShadow)
 		{
 			using (var reader = new BinaryReader(s))
 				for (var i = 0; i < Palette.Size; i++)
@@ -94,7 +92,9 @@ namespace OpenRA.Graphics
 					colors[i] = (uint)((255 << 24) | (r << 16) | (g << 8) | b);
 				}
 
-			colors[0] = 0; // Convert black background to transparency.
+			foreach (var i in remapTransparent)
+				colors[i] = 0;
+
 			foreach (var i in remapShadow)
 				colors[i] = 140u << 24;
 		}
@@ -103,12 +103,12 @@ namespace OpenRA.Graphics
 			: this(p)
 		{
 			for (var i = 0; i < Palette.Size; i++)
-				colors[i] = (uint)r.GetRemappedColor(this.GetColor(i), i).ToArgb();
+				colors[i] = r.GetRemappedColor(this.GetColor(i), i).ToArgb();
 		}
 
 		public ImmutablePalette(IPalette p)
 		{
-			for (int i = 0; i < Palette.Size; i++)
+			for (var i = 0; i < Palette.Size; i++)
 				colors[i] = p[i];
 		}
 
@@ -126,8 +126,8 @@ namespace OpenRA.Graphics
 
 		public uint this[int index]
 		{
-			get { return colors[index]; }
-			set { colors[index] = value; }
+			get => colors[index];
+			set => colors[index] = value;
 		}
 
 		public void CopyToArray(Array destination, int destinationOffset)
@@ -142,7 +142,7 @@ namespace OpenRA.Graphics
 
 		public void SetColor(int index, Color color)
 		{
-			colors[index] = (uint)color.ToArgb();
+			colors[index] = color.ToArgb();
 		}
 
 		public void SetFromPalette(IPalette p)
@@ -153,7 +153,7 @@ namespace OpenRA.Graphics
 		public void ApplyRemap(IPaletteRemap r)
 		{
 			for (var i = 0; i < Palette.Size; i++)
-				colors[i] = (uint)r.GetRemappedColor(this.GetColor(i), i).ToArgb();
+				colors[i] = r.GetRemappedColor(this.GetColor(i), i).ToArgb();
 		}
 	}
 }

OpenRA.Game/Graphics/PaletteReference.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -13,20 +13,20 @@ namespace OpenRA.Graphics
 {
 	public sealed class PaletteReference
 	{
-		readonly float index;
 		readonly HardwarePalette hardwarePalette;
 
 		public readonly string Name;
 		public IPalette Palette { get; internal set; }
-		public float TextureIndex { get { return index / hardwarePalette.Height; } }
-		public float TextureMidIndex { get { return (index + 0.5f) / hardwarePalette.Height; } }
+		public int TextureIndex { get; }
 
 		public PaletteReference(string name, int index, IPalette palette, HardwarePalette hardwarePalette)
 		{
 			Name = name;
 			Palette = palette;
-			this.index = index;
+			TextureIndex = index;
 			this.hardwarePalette = hardwarePalette;
 		}
+
+		public bool HasColorShift => hardwarePalette.HasColorShift(Name);
 	}
 }

OpenRA.Game/Graphics/PlatformInterfaces.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -20,13 +20,12 @@ namespace OpenRA
 		Automatic,
 		ANGLE,
 		Modern,
-		Embedded,
-		Legacy
+		Embedded
 	}
 
 	public interface IPlatform
 	{
-		IPlatformWindow CreateWindow(Size size, WindowMode windowMode, float scaleModifier, int batchSize, int videoDisplay, GLProfile profile, bool enableLegacyGL);
+		IPlatformWindow CreateWindow(Size size, WindowMode windowMode, float scaleModifier, int vertexBatchSize, int indexBatchSize, int videoDisplay, GLProfile profile);
 		ISoundEngine CreateSound(string device);
 		IFont CreateFont(byte[] data);
 	}
@@ -59,6 +58,7 @@ namespace OpenRA
 		int DisplayCount { get; }
 		int CurrentDisplay { get; }
 		bool HasInputFocus { get; }
+		bool IsSuspended { get; }
 
 		event Action<float, float, float, float> OnWindowScaleChanged;
 
@@ -71,6 +71,7 @@ namespace OpenRA
 
 		IHardwareCursor CreateHardwareCursor(string name, Size size, byte[] data, int2 hotspot, bool pixelDouble);
 		void SetHardwareCursor(IHardwareCursor cursor);
+		void SetWindowTitle(string title);
 		void SetRelativeMouseMode(bool mode);
 		void SetScaleModifier(float scale);
 
@@ -81,15 +82,18 @@ namespace OpenRA
 
 	public interface IGraphicsContext : IDisposable
 	{
-		IVertexBuffer<Vertex> CreateVertexBuffer(int size);
+		IVertexBuffer<T> CreateVertexBuffer<T>(int size) where T : struct;
+		T[] CreateVertices<T>(int size) where T : struct;
+		IIndexBuffer CreateIndexBuffer(uint[] indices);
 		ITexture CreateTexture();
 		IFrameBuffer CreateFrameBuffer(Size s);
 		IFrameBuffer CreateFrameBuffer(Size s, Color clearColor);
-		IShader CreateShader(string name);
+		IShader CreateShader(IShaderBindings shaderBindings);
 		void EnableScissor(int x, int y, int width, int height);
 		void DisableScissor();
 		void Present();
 		void DrawPrimitives(PrimitiveType pt, int firstVertex, int numVertices);
+		void DrawElements(int numIndices, int offset);
 		void Clear();
 		void EnableDepthBuffer();
 		void DisableDepthBuffer();
@@ -99,13 +103,30 @@ namespace OpenRA
 		string GLVersion { get; }
 	}
 
-	public interface IVertexBuffer<T> : IDisposable
+	public interface IRenderer
+	{
+		void BeginFrame();
+		void EndFrame();
+		void SetPalette(HardwarePalette palette);
+	}
+
+	public interface IVertexBuffer<T> : IDisposable where T : struct
 	{
 		void Bind();
 		void SetData(T[] vertices, int length);
+
+		/// <summary>
+		/// Upon return `vertices` may reference another array object of at least the same size - containing random values.
+		/// </summary>
+		void SetData(ref T[] vertices, int length);
 		void SetData(T[] vertices, int offset, int start, int length);
 	}
 
+	public interface IIndexBuffer : IDisposable
+	{
+		void Bind();
+	}
+
 	public interface IShader
 	{
 		void SetBool(string name, bool value);
@@ -116,14 +137,26 @@ namespace OpenRA
 		void SetTexture(string param, ITexture texture);
 		void SetMatrix(string param, float[] mtx);
 		void PrepareRender();
+		void Bind();
+	}
+
+	public interface IShaderBindings
+	{
+		string VertexShaderName { get; }
+		string VertexShaderCode { get; }
+		string FragmentShaderName { get; }
+		string FragmentShaderCode { get; }
+		int Stride { get; }
+		ShaderVertexAttribute[] Attributes { get; }
 	}
 
 	public enum TextureScaleFilter { Nearest, Linear }
 
 	public interface ITexture : IDisposable
 	{
-		void SetData(uint[,] colors);
 		void SetData(byte[] colors, int width, int height);
+		void SetFloatData(float[] data, int width, int height);
+		void SetDataFromReadBuffer(Rectangle rect);
 		byte[] GetData();
 		Size Size { get; }
 		TextureScaleFilter ScaleFilter { get; set; }
@@ -145,7 +178,7 @@ namespace OpenRA
 		TriangleList,
 	}
 
-	public struct Range<T>
+	public readonly struct Range<T>
 	{
 		public readonly T Start, End;
 		public Range(T start, T end) { Start = start; End = end; }

OpenRA.Game/Graphics/PlayerColorRemap.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,7 +10,6 @@
 #endregion
 
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using OpenRA.Primitives;
 
@@ -18,43 +17,37 @@ namespace OpenRA.Graphics
 {
 	public class PlayerColorRemap : IPaletteRemap
 	{
-		Dictionary<int, Color> remapColors;
+		readonly int[] remapIndices;
+		readonly float hue;
+		readonly float saturation;
+		readonly float value;
 
-		public static int GetRemapIndex(int[] ramp, int i)
+		public PlayerColorRemap(int[] remapIndices, Color color)
 		{
-			return ramp[i];
-		}
+			this.remapIndices = remapIndices;
 
-		public PlayerColorRemap(int[] ramp, Color c, float rampFraction)
-		{
-			var h = c.GetHue() / 360.0f;
-			var s = c.GetSaturation();
-			var l = c.GetBrightness();
-
-			// Increase luminosity if required to represent the full ramp
-			var rampRange = (byte)((1 - rampFraction) * l);
-			var c1 = Color.FromAhsl(h, s, Math.Max(rampRange, l));
-			var c2 = Color.FromAhsl(h, s, (byte)Math.Max(0, l - rampRange));
-			var baseIndex = ramp[0];
-			var remapRamp = ramp.Select(r => r - ramp[0]);
-			var rampMaxIndex = ramp.Length - 1;
-
-			// reversed remapping
-			if (ramp[0] > ramp[rampMaxIndex])
-			{
-				baseIndex = ramp[rampMaxIndex];
-				for (var i = rampMaxIndex; i > 0; i--)
-					remapRamp = ramp.Select(r => r - ramp[rampMaxIndex]);
-			}
-
-			remapColors = remapRamp.Select((x, i) => (baseIndex + i, Exts.ColorLerp(x / (float)ramp.Length, c1, c2)))
-				.ToDictionary(u => u.Item1, u => u.Item2);
+			var (r, g, b) = color.ToLinear();
+			(hue, saturation, value) = Color.RgbToHsv(r, g, b);
 		}
 
 		public Color GetRemappedColor(Color original, int index)
 		{
-			return remapColors.TryGetValue(index, out var c)
-				? c : original;
+			if (!remapIndices.Contains(index))
+				return original;
+
+			// Color remapping is applied in a linear color space, so start
+			// by undoing the pre-multiplied alpha and gamma corrections
+			var (r, g, b) = original.ToLinear();
+
+			// Calculate the brightness (i.e HSV value) of the original colour
+			// This inlines the single line of Color.RgbToHsv() that we need
+			var value = Math.Max(Math.Max(r, g), b);
+
+			// Construct the new RGB color
+			(r, g, b) = Color.HsvToRgb(hue, saturation, value * this.value);
+
+			// Convert linear back to SRGB and pre-multiply by the alpha
+			return Color.FromLinear(original.A, r, g, b);
 		}
 	}
 }

OpenRA.Game/Graphics/RenderPostProcessPassVertex.cs

@@ -0,0 +1,64 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Runtime.InteropServices;
+
+namespace OpenRA.Graphics
+{
+	[StructLayout(LayoutKind.Sequential)]
+	public readonly struct RenderPostProcessPassVertex
+	{
+		public readonly float X, Y;
+
+		public RenderPostProcessPassVertex(float x, float y)
+		{
+			X = x; Y = y;
+		}
+	}
+
+	[StructLayout(LayoutKind.Sequential)]
+	public readonly struct RenderPostProcessPassTexturedVertex
+	{
+		// 3d position
+		public readonly float X, Y;
+		public readonly float S, T;
+
+		public RenderPostProcessPassTexturedVertex(float x, float y, float s, float t)
+		{
+			X = x; Y = y;
+			S = s; T = t;
+		}
+	}
+
+	public sealed class RenderPostProcessPassShaderBindings : ShaderBindings
+	{
+		public RenderPostProcessPassShaderBindings(string name)
+			: base("postprocess", "postprocess_" + name) { }
+
+		public override ShaderVertexAttribute[] Attributes { get; } = new[]
+		{
+			new ShaderVertexAttribute("aVertexPosition", ShaderVertexAttributeType.Float, 2, 0)
+		};
+	}
+
+	public sealed class RenderPostProcessPassTexturedShaderBindings : ShaderBindings
+	{
+		public RenderPostProcessPassTexturedShaderBindings(string name)
+			: base("postprocess_textured", "postprocess_textured_" + name)
+		{ }
+
+		public override ShaderVertexAttribute[] Attributes { get; } = new[]
+		{
+			new ShaderVertexAttribute("aVertexPosition", ShaderVertexAttributeType.Float, 2, 0),
+			new ShaderVertexAttribute("aVertexTexCoord", ShaderVertexAttributeType.Float, 2, 8),
+		};
+	}
+}

OpenRA.Game/Graphics/Renderable.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
@@ -16,21 +17,38 @@ namespace OpenRA.Graphics
 	public interface IRenderable
 	{
 		WPos Pos { get; }
-		PaletteReference Palette { get; }
 		int ZOffset { get; }
 		bool IsDecoration { get; }
 
-		IRenderable WithPalette(PaletteReference newPalette);
 		IRenderable WithZOffset(int newOffset);
-		IRenderable OffsetBy(WVec offset);
+		IRenderable OffsetBy(in WVec offset);
 		IRenderable AsDecoration();
 
 		IFinalizedRenderable PrepareRender(WorldRenderer wr);
 	}
 
-	public interface ITintableRenderable
+	public interface IPalettedRenderable : IRenderable
 	{
-		IRenderable WithTint(in float3 newTint);
+		PaletteReference Palette { get; }
+		IPalettedRenderable WithPalette(PaletteReference newPalette);
+	}
+
+	[Flags]
+	public enum TintModifiers
+	{
+		None = 0,
+		IgnoreWorldTint = 1,
+		ReplaceColor = 2
+	}
+
+	public interface IModifyableRenderable : IRenderable
+	{
+		float Alpha { get; }
+		float3 Tint { get; }
+		TintModifiers TintModifiers { get; }
+
+		IModifyableRenderable WithAlpha(float newAlpha);
+		IModifyableRenderable WithTint(in float3 newTint, TintModifiers newTintModifiers);
 	}
 
 	public interface IFinalizedRenderable

OpenRA.Game/Graphics/RgbaColorRenderer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -18,17 +18,17 @@ namespace OpenRA.Graphics
 {
 	public class RgbaColorRenderer
 	{
-		static readonly float3 Offset = new float3(0.5f, 0.5f, 0f);
+		static readonly float3 Offset = new(0.5f, 0.5f, 0f);
 
 		readonly SpriteRenderer parent;
-		readonly Vertex[] vertices = new Vertex[6];
+		readonly Vertex[] vertices = new Vertex[4];
 
 		public RgbaColorRenderer(SpriteRenderer parent)
 		{
 			this.parent = parent;
 		}
 
-		public void DrawLine(in float3 start, in float3 end, float width, Color startColor, Color endColor)
+		public void DrawLine(in float3 start, in float3 end, float width, Color startColor, Color endColor, BlendMode blendMode = BlendMode.Alpha)
 		{
 			var delta = (end - start) / (end - start).XY.Length;
 			var corner = width / 2 * new float3(-delta.Y, delta.X, delta.Z);
@@ -45,17 +45,15 @@ namespace OpenRA.Graphics
 			var eb = endColor.B / 255.0f;
 			var ea = endColor.A / 255.0f;
 
-			vertices[0] = new Vertex(start - corner + Offset, sr, sg, sb, sa, 0, 0);
-			vertices[1] = new Vertex(start + corner + Offset, sr, sg, sb, sa, 0, 0);
-			vertices[2] = new Vertex(end + corner + Offset, er, eg, eb, ea, 0, 0);
-			vertices[3] = new Vertex(end + corner + Offset, er, eg, eb, ea, 0, 0);
-			vertices[4] = new Vertex(end - corner + Offset, er, eg, eb, ea, 0, 0);
-			vertices[5] = new Vertex(start - corner + Offset, sr, sg, sb, sa, 0, 0);
+			vertices[0] = new Vertex(start - corner + Offset, sr, sg, sb, sa, 0);
+			vertices[1] = new Vertex(start + corner + Offset, sr, sg, sb, sa, 0);
+			vertices[2] = new Vertex(end + corner + Offset, er, eg, eb, ea, 0);
+			vertices[3] = new Vertex(end - corner + Offset, er, eg, eb, ea, 0);
 
-			parent.DrawRGBAVertices(vertices);
+			parent.DrawRGBAQuad(vertices, blendMode);
 		}
 
-		public void DrawLine(in float3 start, in float3 end, float width, Color color)
+		public void DrawLine(in float3 start, in float3 end, float width, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
 			var delta = (end - start) / (end - start).XY.Length;
 			var corner = width / 2 * new float2(-delta.Y, delta.X);
@@ -66,21 +64,19 @@ namespace OpenRA.Graphics
 			var b = color.B / 255.0f;
 			var a = color.A / 255.0f;
 
-			vertices[0] = new Vertex(start - corner + Offset, r, g, b, a, 0, 0);
-			vertices[1] = new Vertex(start + corner + Offset, r, g, b, a, 0, 0);
-			vertices[2] = new Vertex(end + corner + Offset, r, g, b, a, 0, 0);
-			vertices[3] = new Vertex(end + corner + Offset, r, g, b, a, 0, 0);
-			vertices[4] = new Vertex(end - corner + Offset, r, g, b, a, 0, 0);
-			vertices[5] = new Vertex(start - corner + Offset, r, g, b, a, 0, 0);
-			parent.DrawRGBAVertices(vertices);
+			vertices[0] = new Vertex(start - corner + Offset, r, g, b, a, 0);
+			vertices[1] = new Vertex(start + corner + Offset, r, g, b, a, 0);
+			vertices[2] = new Vertex(end + corner + Offset, r, g, b, a, 0);
+			vertices[3] = new Vertex(end - corner + Offset, r, g, b, a, 0);
+			parent.DrawRGBAQuad(vertices, blendMode);
 		}
 
 		/// <summary>
 		/// Calculate the 2D intersection of two lines.
 		/// Will behave badly if the lines are parallel.
-		/// Z position is the average of a and b (ignores actual intersection point if it exists)
+		/// Z position is the average of a and b (ignores actual intersection point if it exists).
 		/// </summary>
-		float3 IntersectionOf(in float3 a, in float3 da, in float3 b, in float3 db)
+		static float3 IntersectionOf(in float3 a, in float3 da, in float3 b, in float3 db)
 		{
 			var crossA = a.X * (a.Y + da.Y) - a.Y * (a.X + da.X);
 			var crossB = b.X * (b.Y + db.Y) - b.Y * (b.X + db.X);
@@ -90,7 +86,7 @@ namespace OpenRA.Graphics
 			return new float3(x / d, y / d, 0.5f * (a.Z + b.Z));
 		}
 
-		void DrawDisconnectedLine(IEnumerable<float3> points, float width, Color color)
+		void DrawDisconnectedLine(IEnumerable<float3> points, float width, Color color, BlendMode blendMode)
 		{
 			using (var e = points.GetEnumerator())
 			{
@@ -101,13 +97,13 @@ namespace OpenRA.Graphics
 				while (e.MoveNext())
 				{
 					var point = e.Current;
-					DrawLine(lastPoint, point, width, color);
+					DrawLine(lastPoint, point, width, color, blendMode);
 					lastPoint = point;
 				}
 			}
 		}
 
-		void DrawConnectedLine(float3[] points, float width, Color color, bool closed)
+		void DrawConnectedLine(float3[] points, float width, Color color, bool closed, BlendMode blendMode)
 		{
 			// Not a line
 			if (points.Length < 2)
@@ -116,7 +112,7 @@ namespace OpenRA.Graphics
 			// Single segment
 			if (points.Length == 2)
 			{
-				DrawLine(points[0], points[1], width, color);
+				DrawLine(points[0], points[1], width, color, blendMode);
 				return;
 			}
 
@@ -138,7 +134,7 @@ namespace OpenRA.Graphics
 			// Segment is part of closed loop
 			if (closed)
 			{
-				var prev = points[points.Length - 1];
+				var prev = points[^1];
 				var prevDir = (start - prev) / (start - prev).XY.Length;
 				var prevCorner = width / 2 * new float3(-prevDir.Y, prevDir.X, prevDir.Z);
 				ca = IntersectionOf(start - prevCorner, prevDir, start - corner, dir);
@@ -157,13 +153,11 @@ namespace OpenRA.Graphics
 				var cd = closed || i < limit - 1 ? IntersectionOf(end - corner, dir, end - nextCorner, nextDir) : end - corner;
 
 				// Fill segment
-				vertices[0] = new Vertex(ca + Offset, r, g, b, a, 0, 0);
-				vertices[1] = new Vertex(cb + Offset, r, g, b, a, 0, 0);
-				vertices[2] = new Vertex(cc + Offset, r, g, b, a, 0, 0);
-				vertices[3] = new Vertex(cc + Offset, r, g, b, a, 0, 0);
-				vertices[4] = new Vertex(cd + Offset, r, g, b, a, 0, 0);
-				vertices[5] = new Vertex(ca + Offset, r, g, b, a, 0, 0);
-				parent.DrawRGBAVertices(vertices);
+				vertices[0] = new Vertex(ca + Offset, r, g, b, a, 0);
+				vertices[1] = new Vertex(cb + Offset, r, g, b, a, 0);
+				vertices[2] = new Vertex(cc + Offset, r, g, b, a, 0);
+				vertices[3] = new Vertex(cd + Offset, r, g, b, a, 0);
+				parent.DrawRGBAQuad(vertices, blendMode);
 
 				// Advance line segment
 				end = next;
@@ -175,32 +169,39 @@ namespace OpenRA.Graphics
 			}
 		}
 
-		public void DrawLine(IEnumerable<float3> points, float width, Color color, bool connectSegments = false)
+		public void DrawLine(IEnumerable<float3> points, float width, Color color, bool connectSegments = false, BlendMode blendMode = BlendMode.Alpha)
 		{
 			if (!connectSegments)
-				DrawDisconnectedLine(points, width, color);
+				DrawDisconnectedLine(points, width, color, blendMode);
 			else
-				DrawConnectedLine(points as float3[] ?? points.ToArray(), width, color, false);
+				DrawConnectedLine(points as float3[] ?? points.ToArray(), width, color, false, blendMode);
 		}
 
-		public void DrawPolygon(float3[] vertices, float width, Color color)
+		public void DrawPolygon(float3[] vertices, float width, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
-			DrawConnectedLine(vertices, width, color, true);
+			DrawConnectedLine(vertices, width, color, true, blendMode);
 		}
 
-		public void DrawPolygon(float2[] vertices, float width, Color color)
+		public void DrawPolygon(float2[] vertices, float width, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
-			DrawConnectedLine(vertices.Select(v => new float3(v, 0)).ToArray(), width, color, true);
+			DrawConnectedLine(vertices.Select(v => new float3(v, 0)).ToArray(), width, color, true, blendMode);
 		}
 
-		public void DrawRect(in float3 tl, in float3 br, float width, Color color)
+		public void DrawRect(in float3 tl, in float3 br, float width, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
 			var tr = new float3(br.X, tl.Y, tl.Z);
 			var bl = new float3(tl.X, br.Y, br.Z);
-			DrawPolygon(new[] { tl, tr, br, bl }, width, color);
+			DrawPolygon(new[] { tl, tr, br, bl }, width, color, blendMode);
 		}
 
-		public void FillTriangle(in float3 a, in float3 b, in float3 c, Color color)
+		public void FillRect(in float3 tl, in float3 br, Color color, BlendMode blendMode = BlendMode.Alpha)
+		{
+			var tr = new float3(br.X, tl.Y, tl.Z);
+			var bl = new float3(tl.X, br.Y, br.Z);
+			FillRect(tl, tr, br, bl, color, blendMode);
+		}
+
+		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
 			color = Util.PremultiplyAlpha(color);
 			var cr = color.R / 255.0f;
@@ -208,46 +209,21 @@ namespace OpenRA.Graphics
 			var cb = color.B / 255.0f;
 			var ca = color.A / 255.0f;
 
-			vertices[0] = new Vertex(a + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[1] = new Vertex(b + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[2] = new Vertex(c + Offset, cr, cg, cb, ca, 0, 0);
-			parent.DrawRGBAVertices(vertices);
+			vertices[0] = new Vertex(a + Offset, cr, cg, cb, ca, 0);
+			vertices[1] = new Vertex(b + Offset, cr, cg, cb, ca, 0);
+			vertices[2] = new Vertex(c + Offset, cr, cg, cb, ca, 0);
+			vertices[3] = new Vertex(d + Offset, cr, cg, cb, ca, 0);
+			parent.DrawRGBAQuad(vertices, blendMode);
 		}
 
-		public void FillRect(in float3 tl, in float3 br, Color color)
-		{
-			var tr = new float3(br.X, tl.Y, tl.Z);
-			var bl = new float3(tl.X, br.Y, br.Z);
-			FillRect(tl, tr, br, bl, color);
-		}
-
-		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color color)
-		{
-			color = Util.PremultiplyAlpha(color);
-			var cr = color.R / 255.0f;
-			var cg = color.G / 255.0f;
-			var cb = color.B / 255.0f;
-			var ca = color.A / 255.0f;
-
-			vertices[0] = new Vertex(a + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[1] = new Vertex(b + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[2] = new Vertex(c + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[3] = new Vertex(c + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[4] = new Vertex(d + Offset, cr, cg, cb, ca, 0, 0);
-			vertices[5] = new Vertex(a + Offset, cr, cg, cb, ca, 0, 0);
-			parent.DrawRGBAVertices(vertices);
-		}
-
-		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor)
+		public void FillRect(in float3 a, in float3 b, in float3 c, in float3 d, Color topLeftColor, Color topRightColor, Color bottomRightColor, Color bottomLeftColor, BlendMode blendMode = BlendMode.Alpha)
 		{
 			vertices[0] = VertexWithColor(a + Offset, topLeftColor);
 			vertices[1] = VertexWithColor(b + Offset, topRightColor);
 			vertices[2] = VertexWithColor(c + Offset, bottomRightColor);
-			vertices[3] = VertexWithColor(c + Offset, bottomRightColor);
-			vertices[4] = VertexWithColor(d + Offset, bottomLeftColor);
-			vertices[5] = VertexWithColor(a + Offset, topLeftColor);
+			vertices[3] = VertexWithColor(d + Offset, bottomLeftColor);
 
-			parent.DrawRGBAVertices(vertices);
+			parent.DrawRGBAQuad(vertices, blendMode);
 		}
 
 		static Vertex VertexWithColor(in float3 xyz, Color color)
@@ -258,10 +234,10 @@ namespace OpenRA.Graphics
 			var cb = color.B / 255.0f;
 			var ca = color.A / 255.0f;
 
-			return new Vertex(xyz, cr, cg, cb, ca, 0, 0);
+			return new Vertex(xyz, cr, cg, cb, ca, 0);
 		}
 
-		public void FillEllipse(in float3 tl, in float3 br, Color color, int vertices = 32)
+		public void FillEllipse(in float3 tl, in float3 br, Color color, BlendMode blendMode = BlendMode.Alpha)
 		{
 			// TODO: Create an ellipse polygon instead
 			var a = (br.X - tl.X) / 2;
@@ -272,7 +248,7 @@ namespace OpenRA.Graphics
 			{
 				var z = float2.Lerp(tl.Z, br.Z, (y - tl.Y) / (br.Y - tl.Y));
 				var dx = a * (float)Math.Sqrt(1 - (y - yc) * (y - yc) / b / b);
-				DrawLine(new float3(xc - dx, y, z), new float3(xc + dx, y, z), 1, color);
+				DrawLine(new float3(xc - dx, y, z), new float3(xc + dx, y, z), 1, color, blendMode);
 			}
 		}
 	}

OpenRA.Game/Graphics/RgbaSpriteRenderer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -22,44 +22,36 @@ namespace OpenRA.Graphics
 			this.parent = parent;
 		}
 
-		public void DrawSprite(Sprite s, in float3 location, in float3 size)
+		public void DrawSprite(Sprite s, in float3 location, in float3 scale, float rotation = 0f)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
 
-			parent.DrawSprite(s, location, 0, size);
+			parent.DrawSprite(s, 0, location, scale, rotation);
 		}
 
-		public void DrawSprite(Sprite s, in float3 location)
+		public void DrawSprite(Sprite s, in float3 location, float scale = 1f, float rotation = 0f)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
 
-			parent.DrawSprite(s, location, 0, s.Size);
+			parent.DrawSprite(s, 0, location, scale, rotation);
 		}
 
-		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d)
+		public void DrawSprite(Sprite s, in float3 location, float scale, in float3 tint, float alpha, float rotation = 0f)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
 
-			parent.DrawSprite(s, a, b, c, d);
+			parent.DrawSprite(s, 0, location, scale, tint, alpha, rotation);
 		}
 
-		public void DrawSpriteWithTint(Sprite s, in float3 location, in float3 size, in float3 tint)
+		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint, float alpha)
 		{
 			if (s.Channel != TextureChannel.RGBA)
 				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
 
-			parent.DrawSpriteWithTint(s, location, 0, size, tint);
-		}
-
-		public void DrawSpriteWithTint(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint)
-		{
-			if (s.Channel != TextureChannel.RGBA)
-				throw new InvalidOperationException("DrawRGBASprite requires a RGBA sprite.");
-
-			parent.DrawSpriteWithTint(s, a, b, c, d, tint);
+			parent.DrawSprite(s, 0, a, b, c, d, tint, alpha);
 		}
 	}
 }

OpenRA.Game/Graphics/SequenceProvider.cs

@@ -1,148 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation, either version 3 of
- * the License, or (at your option) any later version. For more
- * information, see COPYING.
- */
-#endregion
-
-using System;
-using System.Collections.Generic;
-using OpenRA.FileSystem;
-using OpenRA.Primitives;
-
-namespace OpenRA.Graphics
-{
-	using Sequences = IReadOnlyDictionary<string, Lazy<IReadOnlyDictionary<string, ISpriteSequence>>>;
-	using UnitSequences = Lazy<IReadOnlyDictionary<string, ISpriteSequence>>;
-
-	public interface ISpriteSequence
-	{
-		string Name { get; }
-		int Start { get; }
-		int Length { get; }
-		int Stride { get; }
-		int Facings { get; }
-		int Tick { get; }
-		int ZOffset { get; }
-		int ShadowStart { get; }
-		int ShadowZOffset { get; }
-		int[] Frames { get; }
-		Rectangle Bounds { get; }
-		bool IgnoreWorldTint { get; }
-
-		Sprite GetSprite(int frame);
-		Sprite GetSprite(int frame, WAngle facing);
-		Sprite GetShadow(int frame, WAngle facing);
-	}
-
-	public interface ISpriteSequenceLoader
-	{
-		IReadOnlyDictionary<string, ISpriteSequence> ParseSequences(ModData modData, string tileSet, SpriteCache cache, MiniYamlNode node);
-	}
-
-	public class SequenceProvider : IDisposable
-	{
-		readonly ModData modData;
-		readonly string tileSet;
-		readonly Lazy<Sequences> sequences;
-		readonly Lazy<SpriteCache> spriteCache;
-		public SpriteCache SpriteCache { get { return spriteCache.Value; } }
-
-		readonly Dictionary<string, UnitSequences> sequenceCache = new Dictionary<string, UnitSequences>();
-
-		public SequenceProvider(IReadOnlyFileSystem fileSystem, ModData modData, string tileSet, MiniYaml additionalSequences)
-		{
-			this.modData = modData;
-			this.tileSet = tileSet;
-			sequences = Exts.Lazy(() =>
-			{
-				using (new Support.PerfTimer("LoadSequences"))
-					return Load(fileSystem, additionalSequences);
-			});
-
-			spriteCache = Exts.Lazy(() => new SpriteCache(fileSystem, modData.SpriteLoaders));
-		}
-
-		public ISpriteSequence GetSequence(string unitName, string sequenceName)
-		{
-			if (!sequences.Value.TryGetValue(unitName, out var unitSeq))
-				throw new InvalidOperationException("Unit `{0}` does not have any sequences defined.".F(unitName));
-
-			if (!unitSeq.Value.TryGetValue(sequenceName, out var seq))
-				throw new InvalidOperationException("Unit `{0}` does not have a sequence named `{1}`".F(unitName, sequenceName));
-
-			return seq;
-		}
-
-		public IEnumerable<string> Images { get { return sequences.Value.Keys; } }
-
-		public bool HasSequence(string unitName)
-		{
-			return sequences.Value.ContainsKey(unitName);
-		}
-
-		public bool HasSequence(string unitName, string sequenceName)
-		{
-			if (!sequences.Value.TryGetValue(unitName, out var unitSeq))
-				throw new InvalidOperationException("Unit `{0}` does not have any sequences defined.".F(unitName));
-
-			return unitSeq.Value.ContainsKey(sequenceName);
-		}
-
-		public IEnumerable<string> Sequences(string unitName)
-		{
-			if (!sequences.Value.TryGetValue(unitName, out var unitSeq))
-				throw new InvalidOperationException("Unit `{0}` does not have any sequences defined.".F(unitName));
-
-			return unitSeq.Value.Keys;
-		}
-
-		Sequences Load(IReadOnlyFileSystem fileSystem, MiniYaml additionalSequences)
-		{
-			var nodes = MiniYaml.Load(fileSystem, modData.Manifest.Sequences, additionalSequences);
-			var items = new Dictionary<string, UnitSequences>();
-			foreach (var node in nodes)
-			{
-				// Nodes starting with ^ are inheritable but never loaded directly
-				if (node.Key.StartsWith(ActorInfo.AbstractActorPrefix, StringComparison.Ordinal))
-					continue;
-
-				var key = node.Value.ToLines(node.Key).JoinWith("|");
-
-				if (sequenceCache.TryGetValue(key, out var t))
-					items.Add(node.Key, t);
-				else
-				{
-					t = Exts.Lazy(() => modData.SpriteSequenceLoader.ParseSequences(modData, tileSet, SpriteCache, node));
-					sequenceCache.Add(key, t);
-					items.Add(node.Key, t);
-				}
-			}
-
-			return new ReadOnlyDictionary<string, UnitSequences>(items);
-		}
-
-		public void Preload()
-		{
-			foreach (var sb in SpriteCache.SheetBuilders.Values)
-				sb.Current.CreateBuffer();
-
-			foreach (var unitSeq in sequences.Value.Values)
-				foreach (var seq in unitSeq.Value.Values) { }
-
-			foreach (var sb in SpriteCache.SheetBuilders.Values)
-				sb.Current.ReleaseBuffer();
-		}
-
-		public void Dispose()
-		{
-			if (spriteCache.IsValueCreated)
-				foreach (var sb in SpriteCache.SheetBuilders.Values)
-					sb.Dispose();
-		}
-	}
-}

OpenRA.Game/Graphics/SequenceSet.cs

@@ -0,0 +1,119 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using OpenRA.FileSystem;
+using OpenRA.Primitives;
+
+namespace OpenRA.Graphics
+{
+	public interface ISpriteSequence
+	{
+		string Name { get; }
+		int Length { get; }
+		int Facings { get; }
+		int Tick { get; }
+		int ZOffset { get; }
+		int ShadowZOffset { get; }
+		Rectangle Bounds { get; }
+		bool IgnoreWorldTint { get; }
+		float Scale { get; }
+		void ResolveSprites(SpriteCache cache);
+		Sprite GetSprite(int frame);
+		Sprite GetSprite(int frame, WAngle facing);
+		(Sprite Sprite, WAngle Rotation) GetSpriteWithRotation(int frame, WAngle facing);
+		Sprite GetShadow(int frame, WAngle facing);
+		float GetAlpha(int frame);
+	}
+
+	public interface ISpriteSequenceLoader
+	{
+		int BgraSheetSize { get; }
+		int IndexedSheetSize { get; }
+		IReadOnlyDictionary<string, ISpriteSequence> ParseSequences(ModData modData, string tileSet, SpriteCache cache, MiniYamlNode node);
+	}
+
+	public sealed class SequenceSet : IDisposable
+	{
+		readonly ModData modData;
+		readonly string tileSet;
+		readonly IReadOnlyDictionary<string, IReadOnlyDictionary<string, ISpriteSequence>> images;
+		public SpriteCache SpriteCache { get; }
+
+		public SequenceSet(IReadOnlyFileSystem fileSystem, ModData modData, string tileSet, MiniYaml additionalSequences)
+		{
+			this.modData = modData;
+			this.tileSet = tileSet;
+			SpriteCache = new SpriteCache(fileSystem, modData.SpriteLoaders, modData.SpriteSequenceLoader.BgraSheetSize, modData.SpriteSequenceLoader.IndexedSheetSize);
+			using (new Support.PerfTimer("LoadSequences"))
+				images = Load(fileSystem, additionalSequences);
+		}
+
+		public ISpriteSequence GetSequence(string image, string sequence)
+		{
+			if (!images.TryGetValue(image, out var sequences))
+				throw new InvalidOperationException($"Image `{image}` does not have any sequences defined.");
+
+			if (!sequences.TryGetValue(sequence, out var seq))
+				throw new InvalidOperationException($"Image `{image}` does not have a sequence named `{sequence}`.");
+
+			return seq;
+		}
+
+		public IEnumerable<string> Images => images.Keys;
+
+		public bool HasSequence(string image, string sequence)
+		{
+			if (!images.TryGetValue(image, out var sequences))
+				throw new InvalidOperationException($"Image `{image}` does not have any sequences defined.");
+
+			return sequences.ContainsKey(sequence);
+		}
+
+		public IEnumerable<string> Sequences(string image)
+		{
+			if (!images.TryGetValue(image, out var sequences))
+				throw new InvalidOperationException($"Image `{image}` does not have any sequences defined.");
+
+			return sequences.Keys;
+		}
+
+		IReadOnlyDictionary<string, IReadOnlyDictionary<string, ISpriteSequence>> Load(IReadOnlyFileSystem fileSystem, MiniYaml additionalSequences)
+		{
+			var nodes = MiniYaml.Load(fileSystem, modData.Manifest.Sequences, additionalSequences);
+			var images = new Dictionary<string, IReadOnlyDictionary<string, ISpriteSequence>>();
+			foreach (var node in nodes)
+			{
+				// Nodes starting with ^ are inheritable but never loaded directly
+				if (node.Key.StartsWith(ActorInfo.AbstractActorPrefix))
+					continue;
+
+				images[node.Key] = modData.SpriteSequenceLoader.ParseSequences(modData, tileSet, SpriteCache, node);
+			}
+
+			return images;
+		}
+
+		public void LoadSprites()
+		{
+			SpriteCache.LoadReservations(modData);
+			foreach (var sequences in images.Values)
+				foreach (var sequence in sequences)
+					sequence.Value.ResolveSprites(SpriteCache);
+		}
+
+		public void Dispose()
+		{
+			SpriteCache.Dispose();
+		}
+	}
+}

OpenRA.Game/Graphics/ShaderBindings.cs

@@ -0,0 +1,70 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.IO;
+using System.Linq;
+
+namespace OpenRA.Graphics
+{
+	public enum ShaderVertexAttributeType
+	{
+		// Assign the underlying OpenGL type values
+		// to simplify enum use in the shader
+		Float = 0x1406, // GL_FLOAT
+		Int = 0x1404, // GL_INT
+		UInt = 0x1405 // GL_UNSIGNED_INT
+	}
+
+	public readonly struct ShaderVertexAttribute
+	{
+		public readonly string Name;
+		public readonly ShaderVertexAttributeType Type;
+		public readonly int Components;
+		public readonly int Offset;
+
+		public ShaderVertexAttribute(string name, ShaderVertexAttributeType type, int components, int offset)
+		{
+			Name = name;
+			Type = type;
+			Components = components;
+			Offset = offset;
+		}
+	}
+
+	public abstract class ShaderBindings : IShaderBindings
+	{
+		public string VertexShaderName { get; }
+		public string VertexShaderCode { get; }
+		public string FragmentShaderName { get; }
+		public string FragmentShaderCode { get; }
+		public int Stride { get; }
+
+		public abstract ShaderVertexAttribute[] Attributes { get; }
+
+		protected ShaderBindings(string name)
+			: this(name, name) { }
+
+		protected ShaderBindings(string vertexName, string fragmentName)
+		{
+			Stride = Attributes.Sum(a => a.Components * 4);
+			VertexShaderName = vertexName;
+			VertexShaderCode = GetShaderCode(VertexShaderName + ".vert");
+			FragmentShaderName = fragmentName;
+			FragmentShaderCode = GetShaderCode(FragmentShaderName + ".frag");
+		}
+
+		public static string GetShaderCode(string filename)
+		{
+			var filepath = Path.Combine(Platform.EngineDir, "glsl", filename);
+			return File.ReadAllText(filepath);
+		}
+	}
+}

OpenRA.Game/Graphics/Sheet.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -32,7 +32,7 @@ namespace OpenRA.Graphics
 			return data;
 		}
 
-		public bool Buffered { get { return data != null || texture == null; } }
+		public bool Buffered => data != null || texture == null;
 
 		public Sheet(SheetType type, Size size)
 		{
@@ -79,21 +79,17 @@ namespace OpenRA.Graphics
 
 		public Png AsPng()
 		{
-			var data = GetData();
+			if (Type == SheetType.Indexed)
+				throw new InvalidOperationException("AsPng() cannot be called on Indexed sheets.");
 
-			// Convert BGRA to RGBA
-			for (var i = 0; i < Size.Width * Size.Height; i++)
-			{
-				var temp = data[i * 4];
-				data[i * 4] = data[i * 4 + 2];
-				data[i * 4 + 2] = temp;
-			}
-
-			return new Png(data, Size.Width, Size.Height);
+			return new Png(GetData(), SpriteFrameType.Bgra32, Size.Width, Size.Height);
 		}
 
 		public Png AsPng(TextureChannel channel, IPalette pal)
 		{
+			if (Type != SheetType.Indexed)
+				throw new InvalidOperationException("AsPng(TextureChannel, IPalette) can only be called on Indexed sheets.");
+
 			var d = GetData();
 			var plane = new byte[Size.Width * Size.Height];
 			var dataStride = 4 * Size.Width;
@@ -107,7 +103,7 @@ namespace OpenRA.Graphics
 			for (var i = 0; i < Palette.Size; i++)
 				palColors[i] = pal.GetColor(i);
 
-			return new Png(plane, Size.Width, Size.Height, palColors);
+			return new Png(plane, SpriteFrameType.Indexed8, Size.Width, Size.Height, palColors);
 		}
 
 		public void CreateBuffer()

OpenRA.Game/Graphics/SheetBuilder.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -34,15 +34,16 @@ namespace OpenRA.Graphics
 	public sealed class SheetBuilder : IDisposable
 	{
 		public readonly SheetType Type;
-		readonly List<Sheet> sheets = new List<Sheet>();
+		readonly List<Sheet> sheets = new();
 		readonly Func<Sheet> allocateSheet;
 		readonly int margin;
-
-		Sheet current;
-		TextureChannel channel;
 		int rowHeight = 0;
 		int2 p;
 
+		public Sheet Current { get; private set; }
+		public TextureChannel CurrentChannel { get; private set; }
+		public IEnumerable<Sheet> AllSheets => sheets;
+
 		public static Sheet AllocateSheet(SheetType type, int sheetSize)
 		{
 			return new Sheet(type, new Size(sheetSize, sheetSize));
@@ -52,9 +53,16 @@ namespace OpenRA.Graphics
 		{
 			switch (t)
 			{
-				case SpriteFrameType.Indexed: return SheetType.Indexed;
-				case SpriteFrameType.BGRA: return SheetType.BGRA;
-				default: throw new NotImplementedException("Unknown SpriteFrameType {0}".F(t));
+				case SpriteFrameType.Indexed8:
+					return SheetType.Indexed;
+
+				// Util.FastCopyIntoChannel will automatically convert these to BGRA
+				case SpriteFrameType.Bgra32:
+				case SpriteFrameType.Bgr24:
+				case SpriteFrameType.Rgba32:
+				case SpriteFrameType.Rgb24:
+					return SheetType.BGRA;
+				default: throw new NotImplementedException($"Unknown SpriteFrameType {t}");
 			}
 		}
 
@@ -66,45 +74,36 @@ namespace OpenRA.Graphics
 
 		public SheetBuilder(SheetType t, Func<Sheet> allocateSheet, int margin = 1)
 		{
-			channel = t == SheetType.Indexed ? TextureChannel.Red : TextureChannel.RGBA;
+			CurrentChannel = t == SheetType.Indexed ? TextureChannel.Red : TextureChannel.RGBA;
 			Type = t;
-			current = allocateSheet();
-			sheets.Add(current);
+			Current = allocateSheet();
+			sheets.Add(Current);
 			this.allocateSheet = allocateSheet;
 			this.margin = margin;
 		}
 
-		public Sprite Add(ISpriteFrame frame) { return Add(frame.Data, frame.Size, 0, frame.Offset); }
-		public Sprite Add(byte[] src, Size size) { return Add(src, size, 0, float3.Zero); }
-		public Sprite Add(byte[] src, Size size, float zRamp, in float3 spriteOffset)
+		public Sprite Add(ISpriteFrame frame, bool premultiplied = false) { return Add(frame.Data, frame.Type, frame.Size, 0, frame.Offset, premultiplied); }
+		public Sprite Add(byte[] src, SpriteFrameType type, Size size, bool premultiplied = false) { return Add(src, type, size, 0, float3.Zero, premultiplied); }
+		public Sprite Add(byte[] src, SpriteFrameType type, Size size, float zRamp, in float3 spriteOffset, bool premultiplied = false)
 		{
 			// Don't bother allocating empty sprites
 			if (size.Width == 0 || size.Height == 0)
-				return new Sprite(current, Rectangle.Empty, 0, spriteOffset, channel, BlendMode.Alpha);
+				return new Sprite(Current, Rectangle.Empty, 0, spriteOffset, CurrentChannel, BlendMode.Alpha);
 
 			var rect = Allocate(size, zRamp, spriteOffset);
-			Util.FastCopyIntoChannel(rect, src);
-			current.CommitBufferedData();
+			Util.FastCopyIntoChannel(rect, src, type, premultiplied);
+			Current.CommitBufferedData();
 			return rect;
 		}
 
 		public Sprite Add(Png src, float scale = 1f)
 		{
-			var rect = Allocate(new Size(src.Width, src.Height),  scale);
+			var rect = Allocate(new Size(src.Width, src.Height), scale);
 			Util.FastCopyIntoSprite(rect, src);
-			current.CommitBufferedData();
+			Current.CommitBufferedData();
 			return rect;
 		}
 
-		public Sprite Add(Size size, byte paletteIndex)
-		{
-			var data = new byte[size.Width * size.Height];
-			for (var i = 0; i < data.Length; i++)
-				data[i] = paletteIndex;
-
-			return Add(data, size);
-		}
-
 		TextureChannel? NextChannel(TextureChannel t)
 		{
 			var nextChannel = (int)t + (int)Type;
@@ -117,7 +116,7 @@ namespace OpenRA.Graphics
 		public Sprite Allocate(Size imageSize, float scale = 1f) { return Allocate(imageSize, 0, float3.Zero, scale); }
 		public Sprite Allocate(Size imageSize, float zRamp, in float3 spriteOffset, float scale = 1f)
 		{
-			if (imageSize.Width + p.X + margin > current.Size.Width)
+			if (imageSize.Width + p.X + margin > Current.Size.Width)
 			{
 				p = new int2(0, p.Y + rowHeight + margin);
 				rowHeight = imageSize.Height;
@@ -126,33 +125,29 @@ namespace OpenRA.Graphics
 			if (imageSize.Height > rowHeight)
 				rowHeight = imageSize.Height;
 
-			if (p.Y + imageSize.Height + margin > current.Size.Height)
+			if (p.Y + imageSize.Height + margin > Current.Size.Height)
 			{
-				var next = NextChannel(channel);
+				var next = NextChannel(CurrentChannel);
 				if (next == null)
 				{
-					current.ReleaseBuffer();
-					current = allocateSheet();
-					sheets.Add(current);
-					channel = Type == SheetType.Indexed ? TextureChannel.Red : TextureChannel.RGBA;
+					Current.ReleaseBuffer();
+					Current = allocateSheet();
+					sheets.Add(Current);
+					CurrentChannel = Type == SheetType.Indexed ? TextureChannel.Red : TextureChannel.RGBA;
 				}
 				else
-					channel = next.Value;
+					CurrentChannel = next.Value;
 
 				rowHeight = imageSize.Height;
 				p = int2.Zero;
 			}
 
-			var rect = new Sprite(current, new Rectangle(p.X + margin, p.Y + margin, imageSize.Width, imageSize.Height), zRamp, spriteOffset, channel, BlendMode.Alpha, scale);
+			var rect = new Sprite(Current, new Rectangle(p.X + margin, p.Y + margin, imageSize.Width, imageSize.Height), zRamp, spriteOffset, CurrentChannel, BlendMode.Alpha, scale);
 			p += new int2(imageSize.Width + margin, 0);
 
 			return rect;
 		}
 
-		public Sheet Current { get { return current; } }
-		public TextureChannel CurrentChannel { get { return channel; } }
-		public IEnumerable<Sheet> AllSheets { get { return sheets; } }
-
 		public void Dispose()
 		{
 			foreach (var sheet in sheets)

OpenRA.Game/Graphics/Sprite.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -23,7 +23,6 @@ namespace OpenRA.Graphics
 		public readonly float ZRamp;
 		public readonly float3 Size;
 		public readonly float3 Offset;
-		public readonly float3 FractionalOffset;
 		public readonly float Top, Left, Bottom, Right;
 
 		public Sprite(Sheet sheet, Rectangle bounds, TextureChannel channel, float scale = 1)
@@ -38,13 +37,16 @@ namespace OpenRA.Graphics
 			Channel = channel;
 			Size = scale * new float3(bounds.Size.Width, bounds.Size.Height, bounds.Size.Height * zRamp);
 			BlendMode = blendMode;
-			FractionalOffset = Size.Z != 0 ? offset / Size :
-				new float3(offset.X / Size.X, offset.Y / Size.Y, 0);
 
-			Left = (float)Math.Min(bounds.Left, bounds.Right) / sheet.Size.Width;
-			Top = (float)Math.Min(bounds.Top, bounds.Bottom) / sheet.Size.Height;
-			Right = (float)Math.Max(bounds.Left, bounds.Right) / sheet.Size.Width;
-			Bottom = (float)Math.Max(bounds.Top, bounds.Bottom) / sheet.Size.Height;
+			// Some GPUs suffer from precision issues when rendering into non 1:1 framebuffers that result
+			// in rendering a line of texels that sample outside the sprite rectangle.
+			// Insetting the texture coordinates by a small fraction of a pixel avoids this
+			// with negligible impact on the 1:1 rendering case.
+			const float Inset = 1 / 128f;
+			Left = (Math.Min(bounds.Left, bounds.Right) + Inset) / sheet.Size.Width;
+			Top = (Math.Min(bounds.Top, bounds.Bottom) + Inset) / sheet.Size.Height;
+			Right = (Math.Max(bounds.Left, bounds.Right) - Inset) / sheet.Size.Width;
+			Bottom = (Math.Max(bounds.Top, bounds.Bottom) - Inset) / sheet.Size.Height;
 		}
 	}
 

OpenRA.Game/Graphics/SpriteCache.cs

@@ -0,0 +1,170 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using OpenRA.FileSystem;
+using OpenRA.Primitives;
+
+namespace OpenRA.Graphics
+{
+	public sealed class SpriteCache : IDisposable
+	{
+		public readonly Dictionary<SheetType, SheetBuilder> SheetBuilders;
+		readonly ISpriteLoader[] loaders;
+		readonly IReadOnlyFileSystem fileSystem;
+
+		readonly Dictionary<int, (int[] Frames, MiniYamlNode.SourceLocation Location, Func<ISpriteFrame, ISpriteFrame> AdjustFrame, bool Premultiplied)> spriteReservations = new();
+		readonly Dictionary<string, List<int>> reservationsByFilename = new();
+
+		readonly Dictionary<int, Sprite[]> resolvedSprites = new();
+
+		readonly Dictionary<int, (string Filename, MiniYamlNode.SourceLocation Location)> missingFiles = new();
+
+		int nextReservationToken = 1;
+
+		public SpriteCache(IReadOnlyFileSystem fileSystem, ISpriteLoader[] loaders, int bgraSheetSize, int indexedSheetSize, int bgraSheetMargin = 1, int indexedSheetMargin = 1)
+		{
+			SheetBuilders = new Dictionary<SheetType, SheetBuilder>
+			{
+				{ SheetType.Indexed, new SheetBuilder(SheetType.Indexed, indexedSheetSize, indexedSheetMargin) },
+				{ SheetType.BGRA, new SheetBuilder(SheetType.BGRA, bgraSheetSize, bgraSheetMargin) }
+			};
+
+			this.fileSystem = fileSystem;
+			this.loaders = loaders;
+		}
+
+		public int ReserveSprites(string filename, IEnumerable<int> frames, MiniYamlNode.SourceLocation location, Func<ISpriteFrame, ISpriteFrame> adjustFrame = null, bool premultiplied = false)
+		{
+			var token = nextReservationToken++;
+			spriteReservations[token] = (frames?.ToArray(), location, adjustFrame, premultiplied);
+			reservationsByFilename.GetOrAdd(filename, _ => new List<int>()).Add(token);
+			return token;
+		}
+
+		static ISpriteFrame[] GetFrames(IReadOnlyFileSystem fileSystem, string filename, ISpriteLoader[] loaders, out TypeDictionary metadata)
+		{
+			metadata = null;
+			if (!fileSystem.TryOpen(filename, out var stream))
+				return null;
+
+			using (stream)
+			{
+				foreach (var loader in loaders)
+					if (loader.TryParseSprite(stream, filename, out var frames, out metadata))
+						return frames;
+
+				return null;
+			}
+		}
+
+		public void LoadReservations(ModData modData)
+		{
+			foreach (var sb in SheetBuilders.Values)
+				sb.Current.CreateBuffer();
+
+			var pendingResolve = new List<(
+				string Filename,
+				int FrameIndex,
+				bool Premultiplied,
+				Func<ISpriteFrame, ISpriteFrame> AdjustFrame,
+				ISpriteFrame Frame,
+				Sprite[] SpritesForToken)>();
+			foreach (var (filename, tokens) in reservationsByFilename)
+			{
+				modData.LoadScreen?.Display();
+				var loadedFrames = GetFrames(fileSystem, filename, loaders, out _);
+				foreach (var token in tokens)
+				{
+					if (spriteReservations.TryGetValue(token, out var rs))
+					{
+						if (loadedFrames != null)
+						{
+							var resolved = new Sprite[loadedFrames.Length];
+							resolvedSprites[token] = resolved;
+							var frames = rs.Frames ?? Enumerable.Range(0, loadedFrames.Length);
+
+							foreach (var i in frames)
+							{
+								var frame = loadedFrames[i];
+								if (rs.AdjustFrame != null)
+									frame = rs.AdjustFrame(frame);
+								pendingResolve.Add((filename, i, rs.Premultiplied, rs.AdjustFrame, frame, resolved));
+							}
+						}
+						else
+						{
+							resolvedSprites[token] = null;
+							missingFiles[token] = (filename, rs.Location);
+						}
+					}
+				}
+			}
+
+			spriteReservations.Clear();
+			spriteReservations.TrimExcess();
+			reservationsByFilename.Clear();
+			reservationsByFilename.TrimExcess();
+
+			// When the sheet builder is adding sprites, it reserves height for the tallest sprite seen along the row.
+			// We can achieve better sheet packing by keeping sprites with similar heights together.
+			var orderedPendingResolve = pendingResolve.OrderBy(x => x.Frame.Size.Height);
+
+			var spriteCache = new Dictionary<(
+				string Filename,
+				int FrameIndex,
+				bool Premultiplied,
+				Func<ISpriteFrame, ISpriteFrame> AdjustFrame),
+				Sprite>(pendingResolve.Count);
+			foreach (var (filename, frameIndex, premultiplied, adjustFrame, frame, spritesForToken) in orderedPendingResolve)
+			{
+				// Premultiplied and non-premultiplied sprites must be cached separately
+				// to cover the case where the same image is requested in both versions.
+				spritesForToken[frameIndex] = spriteCache.GetOrAdd(
+					(filename, frameIndex, premultiplied, adjustFrame),
+					_ =>
+					{
+						var sheetBuilder = SheetBuilders[SheetBuilder.FrameTypeToSheetType(frame.Type)];
+						return sheetBuilder.Add(frame, premultiplied);
+					});
+
+				modData.LoadScreen?.Display();
+			}
+
+			foreach (var sb in SheetBuilders.Values)
+				sb.Current.ReleaseBuffer();
+		}
+
+		public Sprite[] ResolveSprites(int token)
+		{
+			if (!resolvedSprites.Remove(token, out var resolved))
+				throw new InvalidOperationException($"{nameof(token)} {token} has either already been resolved, or was never reserved via {nameof(ReserveSprites)}");
+
+			resolvedSprites.TrimExcess();
+
+			if (missingFiles.TryGetValue(token, out var r))
+				throw new FileNotFoundException($"{r.Location}: {r.Filename} not found", r.Filename);
+
+			return resolved;
+		}
+
+		public IEnumerable<(string Filename, MiniYamlNode.SourceLocation Location)> MissingFiles => missingFiles.Values.ToHashSet();
+
+		public void Dispose()
+		{
+			foreach (var sb in SheetBuilders.Values)
+				sb.Dispose();
+		}
+	}
+}

OpenRA.Game/Graphics/SpriteFont.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,7 +10,6 @@
 #endregion
 
 using System;
-using System.Linq;
 using OpenRA.Primitives;
 using OpenRA.Support;
 
@@ -18,10 +17,9 @@ namespace OpenRA.Graphics
 {
 	public sealed class SpriteFont : IDisposable
 	{
-		public int TopOffset { get; private set; }
+		public int TopOffset { get; }
 		readonly int size;
 		readonly SheetBuilder builder;
-		readonly Func<string, float> lineWidth;
 		readonly IFont font;
 		readonly Cache<char, GlyphInfo> glyphs;
 		readonly Cache<(char C, int Radius), Sprite> contrastGlyphs;
@@ -32,7 +30,7 @@ namespace OpenRA.Graphics
 		public SpriteFont(string name, byte[] data, int size, int ascender, float scale, SheetBuilder builder)
 		{
 			if (builder.Type != SheetType.BGRA)
-				throw new ArgumentException("The sheet builder must create BGRA sheets.", "builder");
+				throw new ArgumentException("The sheet builder must create BGRA sheets.", nameof(builder));
 
 			deviceScale = scale;
 			this.size = size;
@@ -43,13 +41,9 @@ namespace OpenRA.Graphics
 			contrastGlyphs = new Cache<(char, int), Sprite>(CreateContrastGlyph);
 			dilationElements = new Cache<int, float[]>(CreateCircularWeightMap);
 
-			// PERF: Cache these delegates for Measure calls.
-			Func<char, float> characterWidth = character => glyphs[character].Advance;
-			lineWidth = line => line.Sum(characterWidth) / deviceScale;
-
 			// Pre-cache small font sizes so glyphs are immediately available when we need them
 			if (size <= 24)
-				using (new PerfTimer("Precache {0} {1}px".F(name, size)))
+				using (new PerfTimer($"Precache {name} {size}px"))
 					for (var n = (char)0x20; n < (char)0x7f; n++)
 						if (glyphs[n] == null)
 							throw new InvalidOperationException();
@@ -89,10 +83,10 @@ namespace OpenRA.Graphics
 				if (g.Sprite != null)
 				{
 					var contrastSprite = contrastGlyphs[(s, screenContrast)];
-					Game.Renderer.RgbaSpriteRenderer.DrawSpriteWithTint(contrastSprite,
+					Game.Renderer.RgbaSpriteRenderer.DrawSprite(contrastSprite,
 						(screen + g.Offset - contrastVector) / deviceScale,
-						contrastSprite.Size / deviceScale,
-						tint);
+						1f / deviceScale,
+						tint, 1f);
 				}
 
 				screen += new int2((int)(g.Advance + 0.5f), 0);
@@ -120,16 +114,16 @@ namespace OpenRA.Graphics
 
 				// Convert screen coordinates back to UI coordinates for drawing
 				if (g.Sprite != null)
-					Game.Renderer.RgbaSpriteRenderer.DrawSpriteWithTint(g.Sprite,
+					Game.Renderer.RgbaSpriteRenderer.DrawSprite(g.Sprite,
 					(screen + g.Offset).ToFloat2() / deviceScale,
-					g.Sprite.Size / deviceScale,
-					tint);
+					1f / deviceScale,
+					tint, 1f);
 
 				screen += new int2((int)(g.Advance + 0.5f), 0);
 			}
 		}
 
-		float2 Rotate(float2 v, float sina, float cosa, float2 offset)
+		static float2 Rotate(float2 v, float sina, float cosa, float2 offset)
 		{
 			return new float2(
 				v.X * cosa - v.Y * sina + offset.X,
@@ -172,12 +166,12 @@ namespace OpenRA.Graphics
 
 					// Offset rotated glyph to align the top-left corner with the screen pixel grid
 					var screenOffset = new float2((int)(ra.X * deviceScale + 0.5f), (int)(ra.Y * deviceScale + 0.5f)) / deviceScale - ra;
-					Game.Renderer.RgbaSpriteRenderer.DrawSpriteWithTint(g.Sprite,
+					Game.Renderer.RgbaSpriteRenderer.DrawSprite(g.Sprite,
 						ra + screenOffset,
 						rb + screenOffset,
 						rc + screenOffset,
 						rd + screenOffset,
-						tint);
+						tint, 1f);
 				}
 
 				p += new float2(g.Advance / deviceScale, 0);
@@ -238,16 +232,26 @@ namespace OpenRA.Graphics
 			if (string.IsNullOrEmpty(text))
 				return new int2(0, size);
 
-			var lines = text.Split('\n');
-			return new int2((int)Math.Ceiling(MaxLineWidth(lines, lineWidth)), lines.Length * size);
+			var lines = text.SplitLines('\n');
+
+			var maxWidth = 0f;
+			var rows = 0;
+			foreach (var line in lines)
+			{
+				rows++;
+				maxWidth = Math.Max(maxWidth, LineWidth(line));
+			}
+
+			return new int2((int)Math.Ceiling(maxWidth), rows * size);
 		}
 
-		static float MaxLineWidth(string[] lines, Func<string, float> lineWidth)
+		float LineWidth(ReadOnlySpan<char> line)
 		{
-			var maxWidth = 0f;
-			foreach (var line in lines)
-				maxWidth = Math.Max(maxWidth, lineWidth(line));
-			return maxWidth;
+			var result = 0f;
+			foreach (var c in line)
+				result += glyphs[c].Advance;
+
+			return result / deviceScale;
 		}
 
 		GlyphInfo CreateGlyph(char c)
@@ -423,7 +427,7 @@ namespace OpenRA.Graphics
 		}
 	}
 
-	class GlyphInfo
+	sealed class GlyphInfo
 	{
 		public float Advance;
 		public int2 Offset;

OpenRA.Game/Graphics/SpriteLoader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -9,20 +9,49 @@
  */
 #endregion
 
-using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using OpenRA.FileSystem;
 using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
-	public enum SpriteFrameType { Indexed, BGRA }
+	/// <summary>
+	/// Describes the format of the pixel data in a ISpriteFrame.
+	/// Note that the channel order is defined for little-endian bytes, so BGRA corresponds
+	/// to a 32bit ARGB value, such as that returned by Color.ToArgb().
+	/// </summary>
+	public enum SpriteFrameType
+	{
+		/// <summary>
+		/// 8 bit index into an external palette.
+		/// </summary>
+		Indexed8,
+
+		/// <summary>
+		/// 32 bit color such as returned by Color.ToArgb() or the bmp file format
+		/// (remember that little-endian systems place the little bits in the first byte).
+		/// </summary>
+		Bgra32,
+
+		/// <summary>
+		/// Like BGRA, but without an alpha channel.
+		/// </summary>
+		Bgr24,
+
+		/// <summary>
+		/// 32 bit color in big-endian format, like png.
+		/// </summary>
+		Rgba32,
+
+		/// <summary>
+		/// Like RGBA, but without an alpha channel.
+		/// </summary>
+		Rgb24
+	}
 
 	public interface ISpriteLoader
 	{
-		bool TryParseSprite(Stream s, out ISpriteFrame[] frames, out TypeDictionary metadata);
+		bool TryParseSprite(Stream s, string filename, out ISpriteFrame[] frames, out TypeDictionary metadata);
 	}
 
 	public interface ISpriteFrame
@@ -45,94 +74,6 @@ namespace OpenRA.Graphics
 		bool DisableExportPadding { get; }
 	}
 
-	public class SpriteCache
-	{
-		public readonly Cache<SpriteFrameType, SheetBuilder> SheetBuilders;
-		readonly ISpriteLoader[] loaders;
-		readonly IReadOnlyFileSystem fileSystem;
-
-		readonly Dictionary<string, List<Sprite[]>> sprites = new Dictionary<string, List<Sprite[]>>();
-		readonly Dictionary<string, ISpriteFrame[]> unloadedFrames = new Dictionary<string, ISpriteFrame[]>();
-		readonly Dictionary<string, TypeDictionary> metadata = new Dictionary<string, TypeDictionary>();
-
-		public SpriteCache(IReadOnlyFileSystem fileSystem, ISpriteLoader[] loaders)
-		{
-			SheetBuilders = new Cache<SpriteFrameType, SheetBuilder>(t => new SheetBuilder(SheetBuilder.FrameTypeToSheetType(t)));
-
-			this.fileSystem = fileSystem;
-			this.loaders = loaders;
-		}
-
-		/// <summary>
-		/// Returns the first set of sprites with the given filename.
-		/// If getUsedFrames is defined then the indices returned by the function call
-		/// are guaranteed to be loaded.  The value of other indices in the returned
-		/// array are undefined and should never be accessed.
-		/// </summary>
-		public Sprite[] this[string filename, Func<int, IEnumerable<int>> getUsedFrames = null]
-		{
-			get
-			{
-				var allSprites = sprites.GetOrAdd(filename);
-				var sprite = allSprites.FirstOrDefault();
-
-				if (!unloadedFrames.TryGetValue(filename, out var unloaded))
-					unloaded = null;
-
-				// This is the first time that the file has been requested
-				// Load all of the frames into the unused buffer and initialize
-				// the loaded cache (initially empty)
-				if (sprite == null)
-				{
-					unloaded = FrameLoader.GetFrames(fileSystem, filename, loaders, out var fileMetadata);
-					unloadedFrames[filename] = unloaded;
-					metadata[filename] = fileMetadata;
-
-					sprite = new Sprite[unloaded.Length];
-					allSprites.Add(sprite);
-				}
-
-				// HACK: The sequence code relies on side-effects from getUsedFrames
-				var indices = getUsedFrames != null ? getUsedFrames(sprite.Length) :
-					Enumerable.Range(0, sprite.Length);
-
-				// Load any unused frames into the SheetBuilder
-				if (unloaded != null)
-				{
-					foreach (var i in indices)
-					{
-						if (unloaded[i] != null)
-						{
-							sprite[i] = SheetBuilders[unloaded[i].Type].Add(unloaded[i]);
-							unloaded[i] = null;
-						}
-					}
-
-					// All frames have been loaded
-					if (unloaded.All(f => f == null))
-						unloadedFrames.Remove(filename);
-				}
-
-				return sprite;
-			}
-		}
-
-		/// <summary>
-		/// Returns a TypeDictionary containing any metadata defined by the frame
-		/// or null if the frame does not define metadata.
-		/// </summary>
-		public TypeDictionary FrameMetadata(string filename)
-		{
-			if (!metadata.TryGetValue(filename, out var fileMetadata))
-			{
-				FrameLoader.GetFrames(fileSystem, filename, loaders, out fileMetadata);
-				metadata[filename] = fileMetadata;
-			}
-
-			return fileMetadata;
-		}
-	}
-
 	public class FrameCache
 	{
 		readonly Cache<string, ISpriteFrame[]> frames;
@@ -142,7 +83,7 @@ namespace OpenRA.Graphics
 			frames = new Cache<string, ISpriteFrame[]>(filename => FrameLoader.GetFrames(fileSystem, filename, loaders, out _));
 		}
 
-		public ISpriteFrame[] this[string filename] { get { return frames[filename]; } }
+		public ISpriteFrame[] this[string filename] => frames[filename];
 	}
 
 	public static class FrameLoader
@@ -151,7 +92,7 @@ namespace OpenRA.Graphics
 		{
 			using (var stream = fileSystem.Open(filename))
 			{
-				var spriteFrames = GetFrames(stream, loaders, out metadata);
+				var spriteFrames = GetFrames(stream, loaders, filename, out metadata);
 				if (spriteFrames == null)
 					throw new InvalidDataException(filename + " is not a valid sprite file!");
 
@@ -159,12 +100,12 @@ namespace OpenRA.Graphics
 			}
 		}
 
-		public static ISpriteFrame[] GetFrames(Stream stream, ISpriteLoader[] loaders, out TypeDictionary metadata)
+		public static ISpriteFrame[] GetFrames(Stream stream, ISpriteLoader[] loaders, string filename, out TypeDictionary metadata)
 		{
 			metadata = null;
 
 			foreach (var loader in loaders)
-				if (loader.TryParseSprite(stream, out var frames, out metadata))
+				if (loader.TryParseSprite(stream, filename, out var frames, out metadata))
 					return frames;
 
 			return null;

OpenRA.Game/Graphics/SpriteRenderable.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -9,79 +9,107 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
-	public struct SpriteRenderable : IRenderable, ITintableRenderable, IFinalizedRenderable
+	public class SpriteRenderable : IPalettedRenderable, IModifyableRenderable, IFinalizedRenderable
 	{
-		public static readonly IEnumerable<IRenderable> None = new IRenderable[0];
+		public static readonly IEnumerable<IRenderable> None = Array.Empty<IRenderable>();
 
 		readonly Sprite sprite;
 		readonly WPos pos;
-		readonly WVec offset;
-		readonly int zOffset;
-		readonly PaletteReference palette;
 		readonly float scale;
-		readonly float3 tint;
-		readonly bool isDecoration;
-		readonly bool ignoreWorldTint;
+		readonly WAngle rotation = WAngle.Zero;
 
-		public SpriteRenderable(Sprite sprite, WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale, bool isDecoration)
-			: this(sprite, pos, offset, zOffset, palette, scale, float3.Ones, isDecoration, false) { }
-
-		public SpriteRenderable(Sprite sprite, WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale, bool isDecoration, bool ignoreWorldTint)
-			: this(sprite, pos, offset, zOffset, palette, scale, float3.Ones, isDecoration, ignoreWorldTint) { }
-
-		public SpriteRenderable(Sprite sprite, WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale, float3 tint, bool isDecoration, bool ignoreWorldTint)
+		public SpriteRenderable(Sprite sprite, WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale, float alpha,
+			float3 tint, TintModifiers tintModifiers, bool isDecoration, WAngle rotation)
 		{
 			this.sprite = sprite;
 			this.pos = pos;
-			this.offset = offset;
-			this.zOffset = zOffset;
-			this.palette = palette;
+			Offset = offset;
+			ZOffset = zOffset;
+			Palette = palette;
 			this.scale = scale;
-			this.tint = tint;
-			this.isDecoration = isDecoration;
-			this.ignoreWorldTint = ignoreWorldTint;
+			this.rotation = rotation;
+			Tint = tint;
+			IsDecoration = isDecoration;
+			TintModifiers = tintModifiers;
+			Alpha = alpha;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the fact that palettes are defined on traits rather than sequences
+			// and can be removed once this has been fixed
+			if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+				Palette = null;
 		}
 
-		public WPos Pos { get { return pos + offset; } }
-		public WVec Offset { get { return offset; } }
-		public PaletteReference Palette { get { return palette; } }
-		public int ZOffset { get { return zOffset; } }
-		public bool IsDecoration { get { return isDecoration; } }
+		public SpriteRenderable(Sprite sprite, WPos pos, WVec offset, int zOffset, PaletteReference palette, float scale, float alpha,
+			float3 tint, TintModifiers tintModifiers, bool isDecoration)
+			: this(sprite, pos, offset, zOffset, palette, scale, alpha, tint, tintModifiers, isDecoration, WAngle.Zero) { }
 
-		public IRenderable WithPalette(PaletteReference newPalette) { return new SpriteRenderable(sprite, pos, offset, zOffset, newPalette, scale, tint, isDecoration, ignoreWorldTint); }
-		public IRenderable WithZOffset(int newOffset) { return new SpriteRenderable(sprite, pos, offset, newOffset, palette, scale, tint, isDecoration, ignoreWorldTint); }
-		public IRenderable OffsetBy(WVec vec) { return new SpriteRenderable(sprite, pos + vec, offset, zOffset, palette, scale, tint, isDecoration, ignoreWorldTint); }
-		public IRenderable AsDecoration() { return new SpriteRenderable(sprite, pos, offset, zOffset, palette, scale, tint, true, ignoreWorldTint); }
+		public WPos Pos => pos + Offset;
+		public WVec Offset { get; }
+		public PaletteReference Palette { get; }
+		public int ZOffset { get; }
+		public bool IsDecoration { get; }
 
-		public IRenderable WithTint(in float3 newTint) { return new SpriteRenderable(sprite, pos, offset, zOffset, palette, scale, newTint, isDecoration, ignoreWorldTint); }
+		public float Alpha { get; }
+		public float3 Tint { get; }
+		public TintModifiers TintModifiers { get; }
+
+		public IPalettedRenderable WithPalette(PaletteReference newPalette)
+		{
+			return new SpriteRenderable(sprite, pos, Offset, ZOffset, newPalette, scale, Alpha, Tint, TintModifiers, IsDecoration, rotation);
+		}
+
+		public IRenderable WithZOffset(int newOffset)
+		{
+			return new SpriteRenderable(sprite, pos, Offset, newOffset, Palette, scale, Alpha, Tint, TintModifiers, IsDecoration, rotation);
+		}
+
+		public IRenderable OffsetBy(in WVec vec)
+		{
+			return new SpriteRenderable(sprite, pos + vec, Offset, ZOffset, Palette, scale, Alpha, Tint, TintModifiers, IsDecoration, rotation);
+		}
+
+		public IRenderable AsDecoration()
+		{
+			return new SpriteRenderable(sprite, pos, Offset, ZOffset, Palette, scale, Alpha, Tint, TintModifiers, true, rotation);
+		}
+
+		public IModifyableRenderable WithAlpha(float newAlpha)
+		{
+			return new SpriteRenderable(sprite, pos, Offset, ZOffset, Palette, scale, newAlpha, Tint, TintModifiers, IsDecoration, rotation);
+		}
+
+		public IModifyableRenderable WithTint(in float3 newTint, TintModifiers newTintModifiers)
+		{
+			return new SpriteRenderable(sprite, pos, Offset, ZOffset, Palette, scale, Alpha, newTint, newTintModifiers, IsDecoration, rotation);
+		}
 
 		float3 ScreenPosition(WorldRenderer wr)
 		{
-			var xy = wr.ScreenPxPosition(pos) + wr.ScreenPxOffset(offset) - (0.5f * scale * sprite.Size.XY).ToInt2();
-
-			// HACK: The z offset needs to be applied somewhere, but this probably is the wrong place.
-			return new float3(xy, sprite.Offset.Z + wr.ScreenZPosition(pos, 0) - 0.5f * scale * sprite.Size.Z);
+			var s = 0.5f * scale * sprite.Size;
+			return wr.Screen3DPxPosition(pos) + wr.ScreenPxOffset(Offset) - new float3((int)s.X, (int)s.Y, s.Z);
 		}
 
 		public IFinalizedRenderable PrepareRender(WorldRenderer wr) { return this; }
 		public void Render(WorldRenderer wr)
 		{
 			var wsr = Game.Renderer.WorldSpriteRenderer;
-			if (ignoreWorldTint)
-				wsr.DrawSprite(sprite, ScreenPosition(wr), palette, scale * sprite.Size);
-			else
-			{
-				var t = tint;
-				if (wr.TerrainLighting != null)
-					t *= wr.TerrainLighting.TintAt(pos);
+			var t = Alpha * Tint;
+			if (wr.TerrainLighting != null && (TintModifiers & TintModifiers.IgnoreWorldTint) == 0)
+				t *= wr.TerrainLighting.TintAt(pos);
 
-				wsr.DrawSpriteWithTint(sprite, ScreenPosition(wr), palette, scale * sprite.Size, t);
-			}
+			// Shader interprets negative alpha as a flag to use the tint colour directly instead of multiplying the sprite colour
+			var a = Alpha;
+			if ((TintModifiers & TintModifiers.ReplaceColor) != 0)
+				a *= -1;
+
+			wsr.DrawSprite(sprite, Palette, ScreenPosition(wr), scale, t, a, rotation.RendererRadians());
 		}
 
 		public void RenderDebugGeometry(WorldRenderer wr)
@@ -89,13 +117,16 @@ namespace OpenRA.Graphics
 			var pos = ScreenPosition(wr) + sprite.Offset;
 			var tl = wr.Viewport.WorldToViewPx(pos);
 			var br = wr.Viewport.WorldToViewPx(pos + sprite.Size);
-			Game.Renderer.RgbaColorRenderer.DrawRect(tl, br, 1, Color.Red);
+			if (rotation == WAngle.Zero)
+				Game.Renderer.RgbaColorRenderer.DrawRect(tl, br, 1, Color.Red);
+			else
+				Game.Renderer.RgbaColorRenderer.DrawPolygon(Util.RotateQuad(tl, br - tl, rotation.RendererRadians()), 1, Color.Red);
 		}
 
 		public Rectangle ScreenBounds(WorldRenderer wr)
 		{
 			var screenOffset = ScreenPosition(wr) + sprite.Offset;
-			return new Rectangle((int)screenOffset.X, (int)screenOffset.Y, (int)sprite.Size.X, (int)sprite.Size.Y);
+			return Util.BoundingRectangle(screenOffset, sprite.Size, rotation.RendererRadians());
 		}
 	}
 }

OpenRA.Game/Graphics/SpriteRenderer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,38 +10,40 @@
 #endregion
 
 using System;
-using System.Linq;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
 	public class SpriteRenderer : Renderer.IBatchRenderer
 	{
-		const int SheetCount = 7;
-		static readonly string[] SheetIndexToTextureName = Exts.MakeArray(SheetCount, i => "Texture{0}".F(i));
+		public const int SheetCount = 8;
+		static readonly string[] SheetIndexToTextureName = Exts.MakeArray(SheetCount, i => $"Texture{i}");
+		static readonly int UintSize = Marshal.SizeOf(typeof(uint));
 
 		readonly Renderer renderer;
 		readonly IShader shader;
 
-		readonly Vertex[] vertices;
+		Vertex[] vertices;
 		readonly Sheet[] sheets = new Sheet[SheetCount];
 
 		BlendMode currentBlend = BlendMode.Alpha;
-		int nv = 0;
-		int ns = 0;
+		int vertexCount = 0;
+		int sheetCount = 0;
 
 		public SpriteRenderer(Renderer renderer, IShader shader)
 		{
 			this.renderer = renderer;
 			this.shader = shader;
-			vertices = new Vertex[renderer.TempBufferSize];
+			vertices = renderer.Context.CreateVertices<Vertex>(renderer.TempVertexBufferSize);
 		}
 
 		public void Flush()
 		{
-			if (nv > 0)
+			if (vertexCount > 0)
 			{
-				for (var i = 0; i < ns; i++)
+				for (var i = 0; i < sheetCount; i++)
 				{
 					shader.SetTexture(SheetIndexToTextureName[i], sheets[i].GetTexture());
 					sheets[i] = null;
@@ -49,11 +51,12 @@ namespace OpenRA.Graphics
 
 				renderer.Context.SetBlendMode(currentBlend);
 				shader.PrepareRender();
-				renderer.DrawBatch(vertices, nv, PrimitiveType.TriangleList);
+
+				renderer.DrawQuadBatch(ref vertices, shader, vertexCount);
 				renderer.Context.SetBlendMode(BlendMode.None);
 
-				nv = 0;
-				ns = 0;
+				vertexCount = 0;
+				sheetCount = 0;
 			}
 		}
 
@@ -61,7 +64,7 @@ namespace OpenRA.Graphics
 		{
 			renderer.CurrentBatchRenderer = this;
 
-			if (s.BlendMode != currentBlend || nv + 6 > renderer.TempBufferSize)
+			if (s.BlendMode != currentBlend || vertexCount + 4 > renderer.TempVertexBufferSize)
 				Flush();
 
 			currentBlend = s.BlendMode;
@@ -69,7 +72,7 @@ namespace OpenRA.Graphics
 			// Check if the sheet (or secondary data sheet) have already been mapped
 			var sheet = s.Sheet;
 			var sheetIndex = 0;
-			for (; sheetIndex < ns; sheetIndex++)
+			for (; sheetIndex < sheetCount; sheetIndex++)
 				if (sheets[sheetIndex] == sheet)
 					break;
 
@@ -78,122 +81,176 @@ namespace OpenRA.Graphics
 			if (ss != null)
 			{
 				var secondarySheet = ss.SecondarySheet;
-				for (; secondarySheetIndex < ns; secondarySheetIndex++)
+				for (; secondarySheetIndex < sheetCount; secondarySheetIndex++)
 					if (sheets[secondarySheetIndex] == secondarySheet)
 						break;
+
+				// If neither sheet has been mapped both index values will be set to ns.
+				// This is fine if they both reference the same texture, but if they don't
+				// we must increment the secondary sheet index to the next free sampler.
+				if (secondarySheetIndex == sheetIndex && secondarySheet != sheet)
+					secondarySheetIndex++;
 			}
 
 			// Make sure that we have enough free samplers to map both if needed, otherwise flush
-			var needSamplers = (sheetIndex == ns ? 1 : 0) + (secondarySheetIndex == ns ? 1 : 0);
-			if (ns + needSamplers >= sheets.Length)
+			if (Math.Max(sheetIndex, secondarySheetIndex) >= sheets.Length)
 			{
 				Flush();
 				sheetIndex = 0;
-				if (ss != null)
-					secondarySheetIndex = 1;
+				secondarySheetIndex = ss != null && ss.SecondarySheet != sheet ? 1 : 0;
 			}
 
-			if (sheetIndex >= ns)
+			if (sheetIndex >= sheetCount)
 			{
 				sheets[sheetIndex] = sheet;
-				ns += 1;
+				sheetCount++;
 			}
 
-			if (secondarySheetIndex >= ns && ss != null)
+			if (secondarySheetIndex >= sheetCount && ss != null)
 			{
 				sheets[secondarySheetIndex] = ss.SecondarySheet;
-				ns += 1;
+				sheetCount++;
 			}
 
 			return new int2(sheetIndex, secondarySheetIndex);
 		}
 
-		internal void DrawSprite(Sprite s, in float3 location, float paletteTextureIndex, in float3 size)
+		static int ResolveTextureIndex(Sprite s, PaletteReference pal)
+		{
+			if (pal == null)
+				return 0;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the limitation that palettes are defined on traits rather than on sequences,
+			// and can be removed once this has been fixed
+			if (s.Channel == TextureChannel.RGBA && !pal.HasColorShift)
+				return 0;
+
+			return pal.TextureIndex;
+		}
+
+		internal void DrawSprite(Sprite s, int paletteTextureIndex, in float3 location, in float3 scale, float rotation = 0f)
 		{
 			var samplers = SetRenderStateForSprite(s);
-			Util.FastCreateQuad(vertices, location + s.FractionalOffset * size, s, samplers, paletteTextureIndex, nv, size, float3.Ones);
-			nv += 6;
+			Util.FastCreateQuad(vertices, location + scale * s.Offset, s, samplers, paletteTextureIndex, vertexCount, scale * s.Size, float3.Ones,
+								1f, rotation);
+			vertexCount += 4;
 		}
 
-		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal)
-		{
-			DrawSprite(s, location, pal.TextureIndex, s.Size);
-		}
-
-		public void DrawSprite(Sprite s, in float3 location, PaletteReference pal, float3 size)
-		{
-			DrawSprite(s, location, pal.TextureIndex, size);
-		}
-
-		public void DrawSprite(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d)
+		internal void DrawSprite(Sprite s, int paletteTextureIndex, in float3 location, float scale, float rotation = 0f)
 		{
 			var samplers = SetRenderStateForSprite(s);
-			Util.FastCreateQuad(vertices, a, b, c, d, s, samplers, 0, float3.Ones, nv);
-			nv += 6;
+			Util.FastCreateQuad(vertices, location + scale * s.Offset, s, samplers, paletteTextureIndex, vertexCount, scale * s.Size, float3.Ones,
+								1f, rotation);
+			vertexCount += 4;
 		}
 
-		internal void DrawSpriteWithTint(Sprite s, in float3 location, float paletteTextureIndex, in float3 size, in float3 tint)
+		public void DrawSprite(Sprite s, PaletteReference pal, in float3 location, float scale = 1f, float rotation = 0f)
+		{
+			DrawSprite(s, ResolveTextureIndex(s, pal), location, scale, rotation);
+		}
+
+		internal void DrawSprite(Sprite s, int paletteTextureIndex, in float3 location, float scale, in float3 tint, float alpha,
+			float rotation = 0f)
 		{
 			var samplers = SetRenderStateForSprite(s);
-			Util.FastCreateQuad(vertices, location + s.FractionalOffset * size, s, samplers, paletteTextureIndex, nv, size, tint);
-			nv += 6;
+			Util.FastCreateQuad(vertices, location + scale * s.Offset, s, samplers, paletteTextureIndex, vertexCount, scale * s.Size, tint, alpha,
+								rotation);
+			vertexCount += 4;
 		}
 
-		public void DrawSpriteWithTint(Sprite s, in float3 location, PaletteReference pal, in float3 size, in float3 tint)
+		public void DrawSprite(Sprite s, PaletteReference pal, in float3 location, float scale, in float3 tint, float alpha,
+			float rotation = 0f)
 		{
-			DrawSpriteWithTint(s, location, pal.TextureIndex, size, tint);
+			DrawSprite(s, ResolveTextureIndex(s, pal), location, scale, tint, alpha, rotation);
 		}
 
-		public void DrawSpriteWithTint(Sprite s, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint)
+		internal void DrawSprite(Sprite s, int paletteTextureIndex, in float3 a, in float3 b, in float3 c, in float3 d, in float3 tint, float alpha)
 		{
 			var samplers = SetRenderStateForSprite(s);
-			Util.FastCreateQuad(vertices, a, b, c, d, s, samplers, 0, tint, nv);
-			nv += 6;
+			Util.FastCreateQuad(vertices, a, b, c, d, s, samplers, paletteTextureIndex, tint, alpha, vertexCount);
+			vertexCount += 4;
 		}
 
-		public void DrawVertexBuffer(IVertexBuffer<Vertex> buffer, int start, int length, PrimitiveType type, Sheet sheet, BlendMode blendMode)
+		public void DrawVertexBuffer(IVertexBuffer<Vertex> buffer, IIndexBuffer indices, int start, int length, IEnumerable<Sheet> sheets, BlendMode blendMode)
 		{
-			shader.SetTexture("Texture0", sheet.GetTexture());
+			var i = 0;
+			foreach (var s in sheets)
+			{
+				if (i >= SheetCount)
+					ThrowSheetOverflow(nameof(sheets));
+
+				if (s != null)
+					shader.SetTexture(SheetIndexToTextureName[i++], s.GetTexture());
+			}
+
 			renderer.Context.SetBlendMode(blendMode);
 			shader.PrepareRender();
-			renderer.DrawBatch(buffer, start, length, type);
+			renderer.DrawQuadBatch(buffer, indices, shader, length, UintSize * start);
 			renderer.Context.SetBlendMode(BlendMode.None);
 		}
 
+		// PERF: methods that throw won't be inlined by the JIT, so extract a static helper for use on hot paths
+		static void ThrowSheetOverflow(string paramName)
+		{
+			throw new ArgumentException($"SpriteRenderer only supports {SheetCount} simultaneous textures", paramName);
+		}
+
 		// For RGBAColorRenderer
-		internal void DrawRGBAVertices(Vertex[] v)
+		internal void DrawRGBAQuad(Vertex[] v, BlendMode blendMode)
 		{
 			renderer.CurrentBatchRenderer = this;
 
-			if (currentBlend != BlendMode.Alpha || nv + v.Length > renderer.TempBufferSize)
+			if (currentBlend != blendMode || vertexCount + 4 > renderer.TempVertexBufferSize)
 				Flush();
 
-			currentBlend = BlendMode.Alpha;
-			Array.Copy(v, 0, vertices, nv, v.Length);
-			nv += v.Length;
+			currentBlend = blendMode;
+
+			Array.Copy(v, 0, vertices, vertexCount, v.Length);
+			vertexCount += 4;
 		}
 
-		public void SetPalette(ITexture palette)
+		public void SetPalette(HardwarePalette palette)
 		{
-			shader.SetTexture("Palette", palette);
+			shader.SetTexture("Palette", palette.Texture);
+			shader.SetTexture("ColorShifts", palette.ColorShifts);
+			shader.SetVec("PaletteRows", palette.Height);
 		}
 
-		public void SetViewportParams(Size screen, float depthScale, float depthOffset, int2 scroll)
+		public void SetViewportParams(Size sheetSize, int downscale, float depthMargin, int2 scroll)
 		{
-			shader.SetVec("Scroll", scroll.X, scroll.Y, scroll.Y);
-			shader.SetVec("r1",
-				2f / screen.Width,
-				2f / screen.Height,
-				-depthScale / screen.Height);
-			shader.SetVec("r2", -1, -1, 1 - depthOffset);
+			// OpenGL only renders x and y coordinates inside [-1, 1] range. We project world coordinates
+			// using p1 to values [0, 2] and then subtract by 1 using p2, where p stands for projection. It's
+			// standard practice for shaders to use a projection matrix, but as we project orthographically
+			// we are able to send less data to the GPU.
+			var width = 2f / (downscale * sheetSize.Width);
+			var height = 2f / (downscale * sheetSize.Height);
 
-			// Texture index is sampled as a float, so convert to pixels then scale
-			shader.SetVec("DepthTextureScale", 128 * depthScale / screen.Height);
+			// Depth is more complicated:
+			// * The OpenGL z axis is inverted (negative is closer) relative to OpenRA (positive is closer).
+			// * We want to avoid clipping pixels that are behind the nominal z == y plane at the
+			//   top of the map, or above the nominal z == y plane at the bottom of the map.
+			//   We therefore expand the depth range by an extra margin that is calculated based on
+			//   the maximum expected world height (see Renderer.InitializeDepthBuffer).
+			// * Sprites can specify an additional per-pixel depth offset map, which is applied in the
+			//   fragment shader. The fragment shader operates in OpenGL window coordinates, not NDC,
+			//   with a depth range [0, 1] corresponding to the NDC [-1, 1]. We must therefore multiply the
+			//   sprite channel value [0, 1] by 255 to find the pixel depth offset, then by our depth scale
+			//   to find the equivalent NDC offset, then divide by 2 to find the window coordinate offset.
+			// * If depthMargin == 0 (which indicates per-pixel depth testing is disabled) sprites that
+			//   extend beyond the top of bottom edges of the screen may be pushed outside [-1, 1] and
+			//   culled by the GPU. We avoid this by forcing everything into the z = 0 plane.
+			var depth = depthMargin != 0f ? 2f / (downscale * (sheetSize.Height + depthMargin)) : 0;
+			shader.SetVec("DepthTextureScale", 128 * depth);
+			shader.SetVec("Scroll", scroll.X, scroll.Y, depthMargin != 0f ? scroll.Y : 0);
+			shader.SetVec("p1", width, height, -depth);
+			shader.SetVec("p2", -1, -1, depthMargin != 0f ? 1 : 0);
 		}
 
-		public void SetDepthPreviewEnabled(bool enabled)
+		public void SetDepthPreview(bool enabled, float contrast, float offset)
 		{
 			shader.SetBool("EnableDepthPreview", enabled);
+			shader.SetVec("DepthPreviewParams", contrast, offset);
 		}
 
 		public void SetAntialiasingPixelsPerTexel(float pxPerTx)

OpenRA.Game/Graphics/TargetLineRenderable.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,14 +15,14 @@ using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
-	public struct TargetLineRenderable : IRenderable, IFinalizedRenderable
+	public class TargetLineRenderable : IRenderable, IFinalizedRenderable
 	{
 		readonly IEnumerable<WPos> waypoints;
 		readonly Color color;
 		readonly int width;
 		readonly int markerSize;
 
-		public TargetLineRenderable(IEnumerable<WPos> waypoints, Color color, int width = 1, int markerSize = 1)
+		public TargetLineRenderable(IEnumerable<WPos> waypoints, Color color, int width, int markerSize)
 		{
 			this.waypoints = waypoints;
 			this.color = color;
@@ -30,14 +30,19 @@ namespace OpenRA.Graphics
 			this.markerSize = markerSize;
 		}
 
-		public WPos Pos { get { return waypoints.First(); } }
-		public PaletteReference Palette { get { return null; } }
-		public int ZOffset { get { return 0; } }
-		public bool IsDecoration { get { return true; } }
+		public WPos Pos => waypoints.First();
+		public int ZOffset => 0;
+		public bool IsDecoration => true;
+
+		public IRenderable WithZOffset(int newOffset) { return this; }
+
+		public IRenderable OffsetBy(in WVec vec)
+		{
+			// Lambdas can't use 'in' variables, so capture a copy for later
+			var offset = vec;
+			return new TargetLineRenderable(waypoints.Select(w => w + offset), color, width, markerSize);
+		}
 
-		public IRenderable WithPalette(PaletteReference newPalette) { return new TargetLineRenderable(waypoints, color); }
-		public IRenderable WithZOffset(int newOffset) { return new TargetLineRenderable(waypoints, color); }
-		public IRenderable OffsetBy(WVec vec) { return new TargetLineRenderable(waypoints.Select(w => w + vec), color); }
 		public IRenderable AsDecoration() { return this; }
 
 		public IFinalizedRenderable PrepareRender(WorldRenderer wr) { return this; }
@@ -51,14 +56,14 @@ namespace OpenRA.Graphics
 			foreach (var b in waypoints.Skip(1).Select(pos => wr.Viewport.WorldToViewPx(wr.Screen3DPosition(pos))))
 			{
 				Game.Renderer.RgbaColorRenderer.DrawLine(a, b, width, color);
-				DrawTargetMarker(wr, color, b, markerSize);
+				DrawTargetMarker(color, b, markerSize);
 				a = b;
 			}
 
-			DrawTargetMarker(wr, color, first);
+			DrawTargetMarker(color, first);
 		}
 
-		public static void DrawTargetMarker(WorldRenderer wr, Color color, int2 screenPos, int size = 1)
+		public static void DrawTargetMarker(Color color, int2 screenPos, int size = 1)
 		{
 			var offset = new int2(size, size);
 			var tl = screenPos - offset;

OpenRA.Game/Graphics/TerrainSpriteLayer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -12,63 +12,72 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using OpenRA.Primitives;
+using System.Runtime.CompilerServices;
 
 namespace OpenRA.Graphics
 {
 	public sealed class TerrainSpriteLayer : IDisposable
 	{
-		static readonly int[] CornerVertexMap = { 0, 1, 2, 2, 3, 0 };
+		// PERF: we can reuse the IndexBuffer as all layers have the same size.
+		static readonly ConditionalWeakTable<World, IndexBufferRc> IndexBuffers = new();
+		readonly IndexBufferRc indexBufferWrapper;
 
-		public readonly Sheet Sheet;
 		public readonly BlendMode BlendMode;
 
+		readonly Sheet[] sheets;
 		readonly Sprite emptySprite;
 
 		readonly IVertexBuffer<Vertex> vertexBuffer;
 		readonly Vertex[] vertices;
 		readonly bool[] ignoreTint;
-		readonly HashSet<int> dirtyRows = new HashSet<int>();
-		readonly int rowStride;
+		readonly HashSet<int> dirtyRows = new();
+		readonly int indexRowStride;
+		readonly int vertexRowStride;
 		readonly bool restrictToBounds;
 
 		readonly WorldRenderer worldRenderer;
 		readonly Map map;
 
-		readonly PaletteReference palette;
+		readonly PaletteReference[] palettes;
 
-		public TerrainSpriteLayer(World world, WorldRenderer wr, Sheet sheet, BlendMode blendMode, PaletteReference palette, bool restrictToBounds)
+		public TerrainSpriteLayer(World world, WorldRenderer wr, Sprite emptySprite, BlendMode blendMode, bool restrictToBounds)
 		{
 			worldRenderer = wr;
 			this.restrictToBounds = restrictToBounds;
-			Sheet = sheet;
+			this.emptySprite = emptySprite;
+			sheets = new Sheet[SpriteRenderer.SheetCount];
 			BlendMode = blendMode;
-			this.palette = palette;
-
 			map = world.Map;
-			rowStride = 6 * map.MapSize.X;
 
-			vertices = new Vertex[rowStride * map.MapSize.Y];
-			vertexBuffer = Game.Renderer.Context.CreateVertexBuffer(vertices.Length);
-			emptySprite = new Sprite(sheet, Rectangle.Empty, TextureChannel.Alpha);
+			vertexRowStride = 4 * map.MapSize.X;
+			vertices = new Vertex[vertexRowStride * map.MapSize.Y];
+			vertexBuffer = Game.Renderer.Context.CreateVertexBuffer<Vertex>(vertices.Length);
 
+			indexRowStride = 6 * map.MapSize.X;
+			lock (IndexBuffers)
+			{
+				indexBufferWrapper = IndexBuffers.GetValue(world, world => new IndexBufferRc(world));
+				indexBufferWrapper.AddRef();
+			}
+
+			palettes = new PaletteReference[map.MapSize.X * map.MapSize.Y];
 			wr.PaletteInvalidated += UpdatePaletteIndices;
 
 			if (wr.TerrainLighting != null)
 			{
-				ignoreTint = new bool[rowStride * map.MapSize.Y];
+				ignoreTint = new bool[vertexRowStride * map.MapSize.Y];
 				wr.TerrainLighting.CellChanged += UpdateTint;
 			}
 		}
 
 		void UpdatePaletteIndices()
 		{
-			// Everything in the layer uses the same palette,
-			// so we can fix the indices in one pass
 			for (var i = 0; i < vertices.Length; i++)
 			{
 				var v = vertices[i];
-				vertices[i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, palette.TextureIndex, v.C, v.R, v.G, v.B);
+				var p = palettes[i / 4]?.TextureIndex ?? 0;
+				var c = (uint)((p & 0xFFFF) << 16) | (v.C & 0xFFFF);
+				vertices[i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, c, v.R, v.G, v.B, v.A);
 			}
 
 			for (var row = 0; row < map.MapSize.Y; row++)
@@ -77,36 +86,35 @@ namespace OpenRA.Graphics
 
 		public void Clear(CPos cell)
 		{
-			Update(cell, null, true);
+			Update(cell, null, null, 1f, 1f, true);
 		}
 
-		public void Update(CPos cell, ISpriteSequence sequence, int frame)
+		public void Update(CPos cell, ISpriteSequence sequence, PaletteReference palette, int frame)
 		{
-			Update(cell, sequence.GetSprite(frame), sequence.IgnoreWorldTint);
+			Update(cell, sequence.GetSprite(frame), palette, sequence.Scale, sequence.GetAlpha(frame), sequence.IgnoreWorldTint);
 		}
 
-		public void Update(CPos cell, Sprite sprite, bool ignoreTint)
+		public void Update(CPos cell, Sprite sprite, PaletteReference palette, float scale = 1f, float alpha = 1f, bool ignoreTint = false)
 		{
 			var xyz = float3.Zero;
 			if (sprite != null)
 			{
 				var cellOrigin = map.CenterOfCell(cell) - new WVec(0, 0, map.Grid.Ramps[map.Ramp[cell]].CenterHeightOffset);
-				xyz = worldRenderer.Screen3DPosition(cellOrigin) + sprite.Offset - 0.5f * sprite.Size;
+				xyz = worldRenderer.Screen3DPosition(cellOrigin) + scale * (sprite.Offset - 0.5f * sprite.Size);
 			}
 
-			Update(cell.ToMPos(map.Grid.Type), sprite, xyz, ignoreTint);
+			Update(cell.ToMPos(map.Grid.Type), sprite, palette, xyz, scale, alpha, ignoreTint);
 		}
 
 		void UpdateTint(MPos uv)
 		{
-			var offset = rowStride * uv.V + 6 * uv.U;
+			var offset = vertexRowStride * uv.V + 4 * uv.U;
 			if (ignoreTint[offset])
 			{
-				var noTint = float3.Ones;
-				for (var i = 0; i < 6; i++)
+				for (var i = 0; i < 4; i++)
 				{
 					var v = vertices[offset + i];
-					vertices[offset + i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, palette.TextureIndex, v.C, noTint);
+					vertices[offset + i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, v.C, v.A * float3.Ones, v.A);
 				}
 
 				return;
@@ -117,7 +125,7 @@ namespace OpenRA.Graphics
 			// transparent for isometric tiles
 			var tl = worldRenderer.TerrainLighting;
 			var pos = map.CenterOfCell(uv.ToCPos(map));
-			var step = map.Grid.Type == MapGridType.RectangularIsometric ? 724 : 512;
+			var step = map.Grid.TileScale / 2;
 			var weights = new[]
 			{
 				tl.TintAt(pos + new WVec(-step, -step, 0)),
@@ -128,34 +136,64 @@ namespace OpenRA.Graphics
 
 			// Apply tint directly to the underlying vertices
 			// This saves us from having to re-query the sprite information, which has not changed
-			for (var i = 0; i < 6; i++)
+			for (var i = 0; i < 4; i++)
 			{
 				var v = vertices[offset + i];
-				vertices[offset + i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, palette.TextureIndex, v.C, weights[CornerVertexMap[i]]);
+				vertices[offset + i] = new Vertex(v.X, v.Y, v.Z, v.S, v.T, v.U, v.V, v.C, v.A * weights[i], v.A);
 			}
 
 			dirtyRows.Add(uv.V);
 		}
 
-		public void Update(MPos uv, Sprite sprite, in float3 pos, bool ignoreTint)
+		int GetOrAddSheetIndex(Sheet sheet)
 		{
+			if (sheet == null)
+				return 0;
+
+			for (var i = 0; i < sheets.Length; i++)
+			{
+				if (sheets[i] == sheet)
+					return i;
+
+				if (sheets[i] == null)
+				{
+					sheets[i] = sheet;
+					return i;
+				}
+			}
+
+			throw new InvalidDataException("Sheet overflow");
+		}
+
+		public void Update(MPos uv, Sprite sprite, PaletteReference palette, in float3 pos, float scale, float alpha, bool ignoreTint)
+		{
+			int2 samplers;
 			if (sprite != null)
 			{
-				if (sprite.Sheet != Sheet)
-					throw new InvalidDataException("Attempted to add sprite from a different sheet");
-
 				if (sprite.BlendMode != BlendMode)
 					throw new InvalidDataException("Attempted to add sprite with a different blend mode");
+
+				samplers = new int2(GetOrAddSheetIndex(sprite.Sheet), GetOrAddSheetIndex((sprite as SpriteWithSecondaryData)?.SecondarySheet));
+
+				// PERF: Remove useless palette assignments for RGBA sprites
+				// HACK: This is working around the limitation that palettes are defined on traits rather than on sequences,
+				// and can be removed once this has been fixed
+				if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+					palette = null;
 			}
 			else
+			{
 				sprite = emptySprite;
+				samplers = int2.Zero;
+			}
 
 			// The vertex buffer does not have geometry for cells outside the map
 			if (!map.Tiles.Contains(uv))
 				return;
 
-			var offset = rowStride * uv.V + 6 * uv.U;
-			Util.FastCreateQuad(vertices, pos, sprite, int2.Zero, palette.TextureIndex, offset, sprite.Size, float3.Ones);
+			var offset = vertexRowStride * uv.V + 4 * uv.U;
+			Util.FastCreateQuad(vertices, pos, sprite, samplers, palette?.TextureIndex ?? 0, offset, scale * sprite.Size, alpha * float3.Ones, alpha);
+			palettes[uv.V * map.MapSize.X + uv.U] = palette;
 
 			if (worldRenderer.TerrainLighting != null)
 			{
@@ -182,13 +220,13 @@ namespace OpenRA.Graphics
 				if (!dirtyRows.Remove(row))
 					continue;
 
-				var rowOffset = rowStride * row;
-				vertexBuffer.SetData(vertices, rowOffset, rowOffset, rowStride);
+				var rowOffset = vertexRowStride * row;
+				vertexBuffer.SetData(vertices, rowOffset, rowOffset, vertexRowStride);
 			}
 
 			Game.Renderer.WorldSpriteRenderer.DrawVertexBuffer(
-				vertexBuffer, rowStride * firstRow, rowStride * (lastRow - firstRow),
-				PrimitiveType.TriangleList, Sheet, BlendMode);
+				vertexBuffer, indexBufferWrapper.Buffer, indexRowStride * firstRow,
+				indexRowStride * (lastRow - firstRow), sheets, BlendMode);
 
 			Game.Renderer.Flush();
 		}
@@ -200,6 +238,29 @@ namespace OpenRA.Graphics
 				worldRenderer.TerrainLighting.CellChanged -= UpdateTint;
 
 			vertexBuffer.Dispose();
+
+			lock (IndexBuffers)
+				indexBufferWrapper.Dispose();
+		}
+
+		sealed class IndexBufferRc : IDisposable
+		{
+			public IIndexBuffer Buffer;
+			int count;
+
+			public IndexBufferRc(World world)
+			{
+				Buffer = Game.Renderer.Context.CreateIndexBuffer(Util.CreateQuadIndices(world.Map.MapSize.X * world.Map.MapSize.Y));
+			}
+
+			public void AddRef() { count++; }
+
+			public void Dispose()
+			{
+				count--;
+				if (count == 0)
+					Buffer.Dispose();
+			}
 		}
 	}
 }

OpenRA.Game/Graphics/Theater.cs

@@ -1,197 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation, either version 3 of
- * the License, or (at your option) any later version. For more
- * information, see COPYING.
- */
-#endregion
-
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using OpenRA.Primitives;
-using OpenRA.Support;
-
-namespace OpenRA.Graphics
-{
-	class TheaterTemplate
-	{
-		public readonly Sprite[] Sprites;
-		public readonly int Stride;
-		public readonly int Variants;
-
-		public TheaterTemplate(Sprite[] sprites, int stride, int variants)
-		{
-			Sprites = sprites;
-			Stride = stride;
-			Variants = variants;
-		}
-	}
-
-	public sealed class Theater : IDisposable
-	{
-		readonly Dictionary<ushort, TheaterTemplate> templates = new Dictionary<ushort, TheaterTemplate>();
-		SheetBuilder sheetBuilder;
-		readonly Sprite missingTile;
-		readonly MersenneTwister random;
-		TileSet tileset;
-
-		public Theater(TileSet tileset, Action<uint, string> onMissingImage = null)
-		{
-			this.tileset = tileset;
-			var allocated = false;
-
-			Func<Sheet> allocate = () =>
-			{
-				if (allocated)
-					throw new SheetOverflowException("Terrain sheet overflow. Try increasing the tileset SheetSize parameter.");
-				allocated = true;
-
-				return new Sheet(SheetType.Indexed, new Size(tileset.SheetSize, tileset.SheetSize));
-			};
-
-			random = new MersenneTwister();
-
-			var frameCache = new FrameCache(Game.ModData.DefaultFileSystem, Game.ModData.SpriteLoaders);
-			foreach (var t in tileset.Templates)
-			{
-				var variants = new List<Sprite[]>();
-
-				foreach (var i in t.Value.Images)
-				{
-					ISpriteFrame[] allFrames;
-					if (onMissingImage != null)
-					{
-						try
-						{
-							allFrames = frameCache[i];
-						}
-						catch (FileNotFoundException)
-						{
-							onMissingImage(t.Key, i);
-							continue;
-						}
-					}
-					else
-						allFrames = frameCache[i];
-
-					var frameCount = tileset.EnableDepth ? allFrames.Length / 2 : allFrames.Length;
-					var indices = t.Value.Frames != null ? t.Value.Frames : Exts.MakeArray(t.Value.TilesCount, j => j);
-
-					var start = indices.Min();
-					var end = indices.Max();
-					if (start < 0 || end >= frameCount)
-						throw new YamlException("Template `{0}` uses frames [{1}..{2}] of {3}, but only [0..{4}] actually exist"
-							.F(t.Key, start, end, i, frameCount - 1));
-
-					variants.Add(indices.Select(j =>
-					{
-						var f = allFrames[j];
-						var tile = t.Value.Contains(j) ? t.Value[j] : null;
-
-						// The internal z axis is inverted from expectation (negative is closer)
-						var zOffset = tile != null ? -tile.ZOffset : 0;
-						var zRamp = tile != null ? tile.ZRamp : 1f;
-						var offset = new float3(f.Offset, zOffset);
-						var type = SheetBuilder.FrameTypeToSheetType(f.Type);
-
-						// Defer SheetBuilder creation until we know what type of frames we are loading!
-						// TODO: Support mixed indexed and BGRA frames
-						if (sheetBuilder == null)
-							sheetBuilder = new SheetBuilder(SheetBuilder.FrameTypeToSheetType(f.Type), allocate);
-						else if (type != sheetBuilder.Type)
-							throw new YamlException("Sprite type mismatch. Terrain sprites must all be either Indexed or RGBA.");
-
-						var s = sheetBuilder.Allocate(f.Size, zRamp, offset);
-						Util.FastCopyIntoChannel(s, f.Data);
-
-						if (tileset.EnableDepth)
-						{
-							var ss = sheetBuilder.Allocate(f.Size, zRamp, offset);
-							Util.FastCopyIntoChannel(ss, allFrames[j + frameCount].Data);
-
-							// s and ss are guaranteed to use the same sheet
-							// because of the custom terrain sheet allocation
-							s = new SpriteWithSecondaryData(s, s.Sheet, ss.Bounds, ss.Channel);
-						}
-
-						return s;
-					}).ToArray());
-				}
-
-				var allSprites = variants.SelectMany(s => s);
-
-				// Ignore the offsets baked into R8 sprites
-				if (tileset.IgnoreTileSpriteOffsets)
-					allSprites = allSprites.Select(s => new Sprite(s.Sheet, s.Bounds, s.ZRamp, new float3(float2.Zero, s.Offset.Z), s.Channel, s.BlendMode));
-
-				if (onMissingImage != null && !variants.Any())
-					continue;
-
-				templates.Add(t.Value.Id, new TheaterTemplate(allSprites.ToArray(), variants.First().Count(), t.Value.Images.Length));
-			}
-
-			// 1x1px transparent tile
-			missingTile = sheetBuilder.Add(new byte[sheetBuilder.Type == SheetType.BGRA ? 4 : 1], new Size(1, 1));
-
-			Sheet.ReleaseBuffer();
-		}
-
-		public bool HasTileSprite(TerrainTile r, int? variant = null)
-		{
-			return TileSprite(r, variant) != missingTile;
-		}
-
-		public Sprite TileSprite(TerrainTile r, int? variant = null)
-		{
-			if (!templates.TryGetValue(r.Type, out var template))
-				return missingTile;
-
-			if (r.Index >= template.Stride)
-				return missingTile;
-
-			var start = template.Variants > 1 ? variant.HasValue ? variant.Value : random.Next(template.Variants) : 0;
-			return template.Sprites[start * template.Stride + r.Index];
-		}
-
-		public Rectangle TemplateBounds(TerrainTemplateInfo template, Size tileSize, MapGridType mapGrid)
-		{
-			Rectangle? templateRect = null;
-
-			var i = 0;
-			for (var y = 0; y < template.Size.Y; y++)
-			{
-				for (var x = 0; x < template.Size.X; x++)
-				{
-					var tile = new TerrainTile(template.Id, (byte)(i++));
-					var tileInfo = tileset.GetTileInfo(tile);
-
-					// Empty tile
-					if (tileInfo == null)
-						continue;
-
-					var sprite = TileSprite(tile);
-					var u = mapGrid == MapGridType.Rectangular ? x : (x - y) / 2f;
-					var v = mapGrid == MapGridType.Rectangular ? y : (x + y) / 2f;
-
-					var tl = new float2(u * tileSize.Width, (v - 0.5f * tileInfo.Height) * tileSize.Height) - 0.5f * sprite.Size;
-					var rect = new Rectangle((int)(tl.X + sprite.Offset.X), (int)(tl.Y + sprite.Offset.Y), (int)sprite.Size.X, (int)sprite.Size.Y);
-					templateRect = templateRect.HasValue ? Rectangle.Union(templateRect.Value, rect) : rect;
-				}
-			}
-
-			return templateRect.HasValue ? templateRect.Value : Rectangle.Empty;
-		}
-
-		public Sheet Sheet { get { return sheetBuilder.Current; } }
-
-		public void Dispose()
-		{
-			sheetBuilder.Dispose();
-		}
-	}
-}

OpenRA.Game/Graphics/UISpriteRenderable.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -13,54 +13,64 @@ using OpenRA.Primitives;
 
 namespace OpenRA.Graphics
 {
-	public struct UISpriteRenderable : IRenderable, IFinalizedRenderable
+	public class UISpriteRenderable : IRenderable, IPalettedRenderable, IFinalizedRenderable
 	{
 		readonly Sprite sprite;
-		readonly WPos effectiveWorldPos;
 		readonly int2 screenPos;
-		readonly int zOffset;
-		readonly PaletteReference palette;
 		readonly float scale;
+		readonly float alpha;
+		readonly float rotation = 0f;
 
-		public UISpriteRenderable(Sprite sprite, WPos effectiveWorldPos, int2 screenPos, int zOffset, PaletteReference palette, float scale)
+		public UISpriteRenderable(Sprite sprite, WPos effectiveWorldPos, int2 screenPos, int zOffset, PaletteReference palette, float scale = 1f, float alpha = 1f, float rotation = 0f)
 		{
 			this.sprite = sprite;
-			this.effectiveWorldPos = effectiveWorldPos;
+			Pos = effectiveWorldPos;
 			this.screenPos = screenPos;
-			this.zOffset = zOffset;
-			this.palette = palette;
+			ZOffset = zOffset;
+			Palette = palette;
 			this.scale = scale;
+			this.alpha = alpha;
+			this.rotation = rotation;
+
+			// PERF: Remove useless palette assignments for RGBA sprites
+			// HACK: This is working around the fact that palettes are defined on traits rather than sequences
+			// and can be removed once this has been fixed
+			if (sprite.Channel == TextureChannel.RGBA && !(palette?.HasColorShift ?? false))
+				Palette = null;
 		}
 
 		// Does not exist in the world, so a world positions don't make sense
-		public WPos Pos { get { return effectiveWorldPos; } }
-		public WVec Offset { get { return WVec.Zero; } }
-		public bool IsDecoration { get { return true; } }
+		public WPos Pos { get; }
+		public WVec Offset => WVec.Zero;
+		public bool IsDecoration => true;
 
-		public PaletteReference Palette { get { return palette; } }
-		public int ZOffset { get { return zOffset; } }
+		public PaletteReference Palette { get; }
+		public int ZOffset { get; }
 
-		public IRenderable WithPalette(PaletteReference newPalette) { return new UISpriteRenderable(sprite, effectiveWorldPos, screenPos, zOffset, newPalette, scale); }
+		public IPalettedRenderable WithPalette(PaletteReference newPalette) { return new UISpriteRenderable(sprite, Pos, screenPos, ZOffset, newPalette, scale, alpha, rotation); }
 		public IRenderable WithZOffset(int newOffset) { return this; }
-		public IRenderable OffsetBy(WVec vec) { return this; }
+		public IRenderable OffsetBy(in WVec vec) { return this; }
 		public IRenderable AsDecoration() { return this; }
 
 		public IFinalizedRenderable PrepareRender(WorldRenderer wr) { return this; }
 		public void Render(WorldRenderer wr)
 		{
-			Game.Renderer.SpriteRenderer.DrawSprite(sprite, screenPos, palette, scale * sprite.Size);
+			Game.Renderer.SpriteRenderer.DrawSprite(sprite, Palette, screenPos, scale, float3.Ones, alpha, rotation);
 		}
 
 		public void RenderDebugGeometry(WorldRenderer wr)
 		{
 			var offset = screenPos + sprite.Offset.XY;
-			Game.Renderer.RgbaColorRenderer.DrawRect(offset, offset + sprite.Size.XY, 1, Color.Red);
+			if (rotation == 0f)
+				Game.Renderer.RgbaColorRenderer.DrawRect(offset, offset + sprite.Size.XY, 1, Color.Red);
+			else
+				Game.Renderer.RgbaColorRenderer.DrawPolygon(Util.RotateQuad(offset, sprite.Size, rotation), 1, Color.Red);
 		}
 
 		public Rectangle ScreenBounds(WorldRenderer wr)
 		{
 			var offset = screenPos + sprite.Offset;
-			return new Rectangle((int)offset.X, (int)offset.Y, (int)sprite.Size.X, (int)sprite.Size.Y);
+			return Util.BoundingRectangle(offset, sprite.Size, rotation);
 		}
 	}
 }

OpenRA.Game/Graphics/Util.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,6 +10,7 @@
 #endregion
 
 using System;
+using System.Runtime.InteropServices;
 using OpenRA.FileFormats;
 using OpenRA.Primitives;
 
@@ -20,29 +21,70 @@ namespace OpenRA.Graphics
 		// yes, our channel order is nuts.
 		static readonly int[] ChannelMasks = { 2, 1, 0, 3 };
 
-		public static void FastCreateQuad(Vertex[] vertices, in float3 o, Sprite r, int2 samplers, float paletteTextureIndex, int nv, in float3 size, in float3 tint)
+		public static uint[] CreateQuadIndices(int quads)
 		{
-			var b = new float3(o.X + size.X, o.Y, o.Z);
-			var c = new float3(o.X + size.X, o.Y + size.Y, o.Z + size.Z);
-			var d = new float3(o.X, o.Y + size.Y, o.Z + size.Z);
-			FastCreateQuad(vertices, o, b, c, d, r, samplers, paletteTextureIndex, tint, nv);
+			var indices = new uint[quads * 6];
+			ReadOnlySpan<uint> cornerVertexMap = stackalloc uint[] { 0, 1, 2, 2, 3, 0 };
+			for (var i = 0; i < indices.Length; i++)
+				indices[i] = cornerVertexMap[i % 6] + (uint)(4 * (i / 6));
+
+			return indices;
+		}
+
+		public static void FastCreateQuad(Vertex[] vertices, in float3 o, Sprite r, int2 samplers, int paletteTextureIndex, int nv,
+			in float3 size, in float3 tint, float alpha, float rotation = 0f)
+		{
+			float3 a, b, c, d;
+
+			// Rotate sprite if rotation angle is not equal to 0
+			if (rotation != 0f)
+			{
+				var center = o + 0.5f * size;
+				var angleSin = (float)Math.Sin(-rotation);
+				var angleCos = (float)Math.Cos(-rotation);
+
+				// Rotated offset for +/- x with +/- y
+				var ra = 0.5f * new float3(
+					size.X * angleCos - size.Y * angleSin,
+					size.X * angleSin + size.Y * angleCos,
+					(size.X * angleSin + size.Y * angleCos) * size.Z / size.Y);
+
+				// Rotated offset for +/- x with -/+ y
+				var rb = 0.5f * new float3(
+					size.X * angleCos + size.Y * angleSin,
+					size.X * angleSin - size.Y * angleCos,
+					(size.X * angleSin - size.Y * angleCos) * size.Z / size.Y);
+
+				a = center - ra;
+				b = center + rb;
+				c = center + ra;
+				d = center - rb;
+			}
+			else
+			{
+				a = o;
+				b = new float3(o.X + size.X, o.Y, o.Z);
+				c = new float3(o.X + size.X, o.Y + size.Y, o.Z + size.Z);
+				d = new float3(o.X, o.Y + size.Y, o.Z + size.Z);
+			}
+
+			FastCreateQuad(vertices, a, b, c, d, r, samplers, paletteTextureIndex, tint, alpha, nv);
 		}
 
 		public static void FastCreateQuad(Vertex[] vertices,
 			in float3 a, in float3 b, in float3 c, in float3 d,
-			Sprite r, int2 samplers, float paletteTextureIndex,
-			in float3 tint, int nv)
+			Sprite r, int2 samplers, int paletteTextureIndex,
+			in float3 tint, float alpha, int nv)
 		{
 			float sl = 0;
 			float st = 0;
 			float sr = 0;
 			float sb = 0;
 
-			// See shp.vert for documentation on the channel attribute format
+			// See combined.vert for documentation on the channel attribute format
 			var attribC = r.Channel == TextureChannel.RGBA ? 0x02 : ((byte)r.Channel) << 1 | 0x01;
 			attribC |= samplers.X << 6;
-			var ss = r as SpriteWithSecondaryData;
-			if (ss != null)
+			if (r is SpriteWithSecondaryData ss)
 			{
 				sl = ss.SecondaryLeft;
 				st = ss.SecondaryTop;
@@ -53,54 +95,33 @@ namespace OpenRA.Graphics
 				attribC |= samplers.Y << 9;
 			}
 
-			var fAttribC = (float)attribC;
-			vertices[nv] = new Vertex(a, r.Left, r.Top, sl, st, paletteTextureIndex, fAttribC, tint);
-			vertices[nv + 1] = new Vertex(b, r.Right, r.Top, sr, st, paletteTextureIndex, fAttribC, tint);
-			vertices[nv + 2] = new Vertex(c, r.Right, r.Bottom, sr, sb, paletteTextureIndex, fAttribC, tint);
-			vertices[nv + 3] = new Vertex(c, r.Right, r.Bottom, sr, sb, paletteTextureIndex, fAttribC, tint);
-			vertices[nv + 4] = new Vertex(d, r.Left, r.Bottom, sl, sb, paletteTextureIndex, fAttribC, tint);
-			vertices[nv + 5] = new Vertex(a, r.Left, r.Top, sl, st, paletteTextureIndex, fAttribC, tint);
+			attribC |= (paletteTextureIndex & 0xFFFF) << 16;
+
+			var uAttribC = (uint)attribC;
+			vertices[nv] = new Vertex(a, r.Left, r.Top, sl, st, uAttribC, tint, alpha);
+			vertices[nv + 1] = new Vertex(b, r.Right, r.Top, sr, st, uAttribC, tint, alpha);
+			vertices[nv + 2] = new Vertex(c, r.Right, r.Bottom, sr, sb, uAttribC, tint, alpha);
+			vertices[nv + 3] = new Vertex(d, r.Left, r.Bottom, sl, sb, uAttribC, tint, alpha);
 		}
 
-		public static void FastCopyIntoChannel(Sprite dest, byte[] src)
+		public static void FastCopyIntoChannel(Sprite dest, byte[] src, SpriteFrameType srcType, bool premultiplied = false)
 		{
 			var destData = dest.Sheet.GetData();
+			var stride = dest.Sheet.Size.Width;
+			var x = dest.Bounds.Left;
+			var y = dest.Bounds.Top;
 			var width = dest.Bounds.Width;
 			var height = dest.Bounds.Height;
 
 			if (dest.Channel == TextureChannel.RGBA)
 			{
-				var destStride = dest.Sheet.Size.Width;
-				unsafe
-				{
-					// Cast the data to an int array so we can copy the src data directly
-					fixed (byte* bd = &destData[0])
-					{
-						var data = (int*)bd;
-						var x = dest.Bounds.Left;
-						var y = dest.Bounds.Top;
-
-						var k = 0;
-						for (var j = 0; j < height; j++)
-						{
-							for (var i = 0; i < width; i++)
-							{
-								var r = src[k++];
-								var g = src[k++];
-								var b = src[k++];
-								var a = src[k++];
-								var cc = Color.FromArgb(a, r, g, b);
-
-								data[(y + j) * destStride + x + i] = PremultiplyAlpha(cc).ToArgb();
-							}
-						}
-					}
-				}
+				CopyIntoRgba(src, srcType, premultiplied, destData, x, y, width, height, stride);
 			}
 			else
 			{
-				var destStride = dest.Sheet.Size.Width * 4;
-				var destOffset = destStride * dest.Bounds.Top + dest.Bounds.Left * 4 + ChannelMasks[(int)dest.Channel];
+				// Copy into single channel of destination.
+				var destStride = stride * 4;
+				var destOffset = destStride * y + x * 4 + ChannelMasks[(int)dest.Channel];
 				var destSkip = destStride - 4 * width;
 
 				var srcOffset = 0;
@@ -117,46 +138,185 @@ namespace OpenRA.Graphics
 			}
 		}
 
+		static void CopyIntoRgba(
+			byte[] src, SpriteFrameType srcType, bool premultiplied, byte[] dest, int x, int y, int width, int height, int stride)
+		{
+			var si = 0;
+			var di = y * stride + x;
+			var d = MemoryMarshal.Cast<byte, uint>(dest);
+
+			// SpriteFrameType.Brga32 is a common source format, and it matches the destination format.
+			// Provide a fast past that just performs memory copies.
+			if (srcType == SpriteFrameType.Bgra32)
+			{
+				var s = MemoryMarshal.Cast<byte, uint>(src);
+				for (var h = 0; h < height; h++)
+				{
+					s[si..(si + width)].CopyTo(d[di..(di + width)]);
+
+					if (!premultiplied)
+					{
+						for (var w = 0; w < width; w++)
+						{
+							d[di] = PremultiplyAlpha(Color.FromArgb(d[di])).ToArgb();
+							di++;
+						}
+
+						di -= width;
+					}
+
+					si += width;
+					di += stride;
+				}
+
+				return;
+			}
+
+			for (var h = 0; h < height; h++)
+			{
+				for (var w = 0; w < width; w++)
+				{
+					byte r, g, b, a;
+					switch (srcType)
+					{
+						case SpriteFrameType.Bgra32:
+						case SpriteFrameType.Bgr24:
+							b = src[si++];
+							g = src[si++];
+							r = src[si++];
+							a = srcType == SpriteFrameType.Bgra32 ? src[si++] : byte.MaxValue;
+							break;
+
+						case SpriteFrameType.Rgba32:
+						case SpriteFrameType.Rgb24:
+							r = src[si++];
+							g = src[si++];
+							b = src[si++];
+							a = srcType == SpriteFrameType.Rgba32 ? src[si++] : byte.MaxValue;
+							break;
+
+						default:
+							throw new InvalidOperationException($"Unknown SpriteFrameType {srcType}");
+					}
+
+					var c = Color.FromArgb(a, r, g, b);
+					if (!premultiplied)
+						c = PremultiplyAlpha(c);
+					d[di++] = c.ToArgb();
+				}
+
+				di += stride - width;
+			}
+		}
+
 		public static void FastCopyIntoSprite(Sprite dest, Png src)
 		{
 			var destData = dest.Sheet.GetData();
-			var destStride = dest.Sheet.Size.Width;
+			var stride = dest.Sheet.Size.Width;
+			var x = dest.Bounds.Left;
+			var y = dest.Bounds.Top;
 			var width = dest.Bounds.Width;
 			var height = dest.Bounds.Height;
 
-			unsafe
+			var si = 0;
+			var di = y * stride + x;
+			var d = MemoryMarshal.Cast<byte, uint>(destData);
+
+			for (var h = 0; h < height; h++)
 			{
-				// Cast the data to an int array so we can copy the src data directly
-				fixed (byte* bd = &destData[0])
+				for (var w = 0; w < width; w++)
 				{
-					var data = (int*)bd;
-					var x = dest.Bounds.Left;
-					var y = dest.Bounds.Top;
-
-					var k = 0;
-					for (var j = 0; j < height; j++)
+					Color c;
+					switch (src.Type)
 					{
-						for (var i = 0; i < width; i++)
-						{
-							Color cc;
-							if (src.Palette == null)
-							{
-								var r = src.Data[k++];
-								var g = src.Data[k++];
-								var b = src.Data[k++];
-								var a = src.Data[k++];
-								cc = Color.FromArgb(a, r, g, b);
-							}
-							else
-								cc = src.Palette[src.Data[k++]];
+						case SpriteFrameType.Indexed8:
+							c = src.Palette[src.Data[si++]];
+							break;
 
-							data[(y + j) * destStride + x + i] = PremultiplyAlpha(cc).ToArgb();
-						}
+						case SpriteFrameType.Rgba32:
+						case SpriteFrameType.Rgb24:
+							var r = src.Data[si++];
+							var g = src.Data[si++];
+							var b = src.Data[si++];
+							var a = src.Type == SpriteFrameType.Rgba32 ? src.Data[si++] : byte.MaxValue;
+							c = Color.FromArgb(a, r, g, b);
+							break;
+
+						// PNGs don't support BGR[A], so no need to include them here
+						default:
+							throw new InvalidOperationException($"Unknown SpriteFrameType {src.Type}");
 					}
+
+					d[di++] = PremultiplyAlpha(c).ToArgb();
 				}
+
+				di += stride - width;
 			}
 		}
 
+		/// <summary>Rotates a quad about its center in the x-y plane.</summary>
+		/// <param name="tl">The top left vertex of the quad.</param>
+		/// <param name="size">A float3 containing the X, Y, and Z lengths of the quad.</param>
+		/// <param name="rotation">The number of radians to rotate by.</param>
+		/// <returns>An array of four vertices representing the rotated quad (top-left, top-right, bottom-right, bottom-left).</returns>
+		public static float3[] RotateQuad(float3 tl, float3 size, float rotation)
+		{
+			var center = tl + 0.5f * size;
+			var angleSin = (float)Math.Sin(-rotation);
+			var angleCos = (float)Math.Cos(-rotation);
+
+			// Rotated offset for +/- x with +/- y
+			var ra = 0.5f * new float3(
+				size.X * angleCos - size.Y * angleSin,
+				size.X * angleSin + size.Y * angleCos,
+				(size.X * angleSin + size.Y * angleCos) * size.Z / size.Y);
+
+			// Rotated offset for +/- x with -/+ y
+			var rb = 0.5f * new float3(
+				size.X * angleCos + size.Y * angleSin,
+				size.X * angleSin - size.Y * angleCos,
+				(size.X * angleSin - size.Y * angleCos) * size.Z / size.Y);
+
+			return new float3[]
+			{
+				center - ra,
+				center + rb,
+				center + ra,
+				center - rb
+			};
+		}
+
+		/// <summary>
+		/// Returns the bounds of an object. Used for determining which objects need to be rendered on screen, and which do not.
+		/// </summary>
+		/// <param name="offset">The top left vertex of the object.</param>
+		/// <param name="size">A float 3 containing the X, Y, and Z lengths of the object.</param>
+		/// <param name="rotation">The angle to rotate the object by (use 0f if there is no rotation).</param>
+		public static Rectangle BoundingRectangle(float3 offset, float3 size, float rotation)
+		{
+			if (rotation == 0f)
+				return new Rectangle((int)offset.X, (int)offset.Y, (int)size.X, (int)size.Y);
+
+			var rotatedQuad = RotateQuad(offset, size, rotation);
+			var minX = rotatedQuad[0].X;
+			var maxX = rotatedQuad[0].X;
+			var minY = rotatedQuad[0].Y;
+			var maxY = rotatedQuad[0].Y;
+			for (var i = 1; i < rotatedQuad.Length; i++)
+			{
+				minX = Math.Min(rotatedQuad[i].X, minX);
+				maxX = Math.Max(rotatedQuad[i].X, maxX);
+				minY = Math.Min(rotatedQuad[i].Y, minY);
+				maxY = Math.Max(rotatedQuad[i].Y, maxY);
+			}
+
+			return new Rectangle(
+				(int)minX,
+				(int)minY,
+				(int)Math.Ceiling(maxX) - (int)minX,
+				(int)Math.Ceiling(maxY) - (int)minY);
+		}
+
 		public static Color PremultiplyAlpha(Color c)
 		{
 			if (c.A == byte.MaxValue)
@@ -176,239 +336,5 @@ namespace OpenRA.Graphics
 				(int)((byte)(t * a2 * c2.G + 0.5f) + (1 - t) * (byte)(a1 * c1.G + 0.5f)),
 				(int)((byte)(t * a2 * c2.B + 0.5f) + (1 - t) * (byte)(a1 * c1.B + 0.5f))));
 		}
-
-		public static float[] IdentityMatrix()
-		{
-			return Exts.MakeArray(16, j => (j % 5 == 0) ? 1.0f : 0);
-		}
-
-		public static float[] ScaleMatrix(float sx, float sy, float sz)
-		{
-			var mtx = IdentityMatrix();
-			mtx[0] = sx;
-			mtx[5] = sy;
-			mtx[10] = sz;
-			return mtx;
-		}
-
-		public static float[] TranslationMatrix(float x, float y, float z)
-		{
-			var mtx = IdentityMatrix();
-			mtx[12] = x;
-			mtx[13] = y;
-			mtx[14] = z;
-			return mtx;
-		}
-
-		public static float[] MatrixMultiply(float[] lhs, float[] rhs)
-		{
-			var mtx = new float[16];
-			for (var i = 0; i < 4; i++)
-				for (var j = 0; j < 4; j++)
-				{
-					mtx[4 * i + j] = 0;
-					for (var k = 0; k < 4; k++)
-						mtx[4 * i + j] += lhs[4 * k + j] * rhs[4 * i + k];
-				}
-
-			return mtx;
-		}
-
-		public static float[] MatrixVectorMultiply(float[] mtx, float[] vec)
-		{
-			var ret = new float[4];
-			for (var j = 0; j < 4; j++)
-			{
-				ret[j] = 0;
-				for (var k = 0; k < 4; k++)
-					ret[j] += mtx[4 * k + j] * vec[k];
-			}
-
-			return ret;
-		}
-
-		public static float[] MatrixInverse(float[] m)
-		{
-			var mtx = new float[16];
-
-			mtx[0] = m[5] * m[10] * m[15] -
-				m[5] * m[11] * m[14] -
-				m[9] * m[6] * m[15] +
-				m[9] * m[7] * m[14] +
-				m[13] * m[6] * m[11] -
-				m[13] * m[7] * m[10];
-
-			mtx[4] = -m[4] * m[10] * m[15] +
-				m[4] * m[11] * m[14] +
-				m[8] * m[6] * m[15] -
-				m[8] * m[7] * m[14] -
-				m[12] * m[6] * m[11] +
-				m[12] * m[7] * m[10];
-
-			mtx[8] = m[4] * m[9] * m[15] -
-				m[4] * m[11] * m[13] -
-				m[8] * m[5] * m[15] +
-				m[8] * m[7] * m[13] +
-				m[12] * m[5] * m[11] -
-				m[12] * m[7] * m[9];
-
-			mtx[12] = -m[4] * m[9] * m[14] +
-				m[4] * m[10] * m[13] +
-				m[8] * m[5] * m[14] -
-				m[8] * m[6] * m[13] -
-				m[12] * m[5] * m[10] +
-				m[12] * m[6] * m[9];
-
-			mtx[1] = -m[1] * m[10] * m[15] +
-				m[1] * m[11] * m[14] +
-				m[9] * m[2] * m[15] -
-				m[9] * m[3] * m[14] -
-				m[13] * m[2] * m[11] +
-				m[13] * m[3] * m[10];
-
-			mtx[5] = m[0] * m[10] * m[15] -
-				m[0] * m[11] * m[14] -
-				m[8] * m[2] * m[15] +
-				m[8] * m[3] * m[14] +
-				m[12] * m[2] * m[11] -
-				m[12] * m[3] * m[10];
-
-			mtx[9] = -m[0] * m[9] * m[15] +
-				m[0] * m[11] * m[13] +
-				m[8] * m[1] * m[15] -
-				m[8] * m[3] * m[13] -
-				m[12] * m[1] * m[11] +
-				m[12] * m[3] * m[9];
-
-			mtx[13] = m[0] * m[9] * m[14] -
-				m[0] * m[10] * m[13] -
-				m[8] * m[1] * m[14] +
-				m[8] * m[2] * m[13] +
-				m[12] * m[1] * m[10] -
-				m[12] * m[2] * m[9];
-
-			mtx[2] = m[1] * m[6] * m[15] -
-				m[1] * m[7] * m[14] -
-				m[5] * m[2] * m[15] +
-				m[5] * m[3] * m[14] +
-				m[13] * m[2] * m[7] -
-				m[13] * m[3] * m[6];
-
-			mtx[6] = -m[0] * m[6] * m[15] +
-				m[0] * m[7] * m[14] +
-				m[4] * m[2] * m[15] -
-				m[4] * m[3] * m[14] -
-				m[12] * m[2] * m[7] +
-				m[12] * m[3] * m[6];
-
-			mtx[10] = m[0] * m[5] * m[15] -
-				m[0] * m[7] * m[13] -
-				m[4] * m[1] * m[15] +
-				m[4] * m[3] * m[13] +
-				m[12] * m[1] * m[7] -
-				m[12] * m[3] * m[5];
-
-			mtx[14] = -m[0] * m[5] * m[14] +
-				m[0] * m[6] * m[13] +
-				m[4] * m[1] * m[14] -
-				m[4] * m[2] * m[13] -
-				m[12] * m[1] * m[6] +
-				m[12] * m[2] * m[5];
-
-			mtx[3] = -m[1] * m[6] * m[11] +
-				m[1] * m[7] * m[10] +
-				m[5] * m[2] * m[11] -
-				m[5] * m[3] * m[10] -
-				m[9] * m[2] * m[7] +
-				m[9] * m[3] * m[6];
-
-			mtx[7] = m[0] * m[6] * m[11] -
-				m[0] * m[7] * m[10] -
-				m[4] * m[2] * m[11] +
-				m[4] * m[3] * m[10] +
-				m[8] * m[2] * m[7] -
-				m[8] * m[3] * m[6];
-
-			mtx[11] = -m[0] * m[5] * m[11] +
-				m[0] * m[7] * m[9] +
-				m[4] * m[1] * m[11] -
-				m[4] * m[3] * m[9] -
-				m[8] * m[1] * m[7] +
-				m[8] * m[3] * m[5];
-
-			mtx[15] = m[0] * m[5] * m[10] -
-				m[0] * m[6] * m[9] -
-				m[4] * m[1] * m[10] +
-				m[4] * m[2] * m[9] +
-				m[8] * m[1] * m[6] -
-				m[8] * m[2] * m[5];
-
-			var det = m[0] * mtx[0] + m[1] * mtx[4] + m[2] * mtx[8] + m[3] * mtx[12];
-			if (det == 0)
-				return null;
-
-			for (var i = 0; i < 16; i++)
-				mtx[i] *= 1 / det;
-
-			return mtx;
-		}
-
-		public static float[] MakeFloatMatrix(Int32Matrix4x4 imtx)
-		{
-			var multipler = 1f / imtx.M44;
-			return new[]
-			{
-				imtx.M11 * multipler,
-				imtx.M12 * multipler,
-				imtx.M13 * multipler,
-				imtx.M14 * multipler,
-
-				imtx.M21 * multipler,
-				imtx.M22 * multipler,
-				imtx.M23 * multipler,
-				imtx.M24 * multipler,
-
-				imtx.M31 * multipler,
-				imtx.M32 * multipler,
-				imtx.M33 * multipler,
-				imtx.M34 * multipler,
-
-				imtx.M41 * multipler,
-				imtx.M42 * multipler,
-				imtx.M43 * multipler,
-				imtx.M44 * multipler,
-			};
-		}
-
-		public static float[] MatrixAABBMultiply(float[] mtx, float[] bounds)
-		{
-			// Corner offsets
-			var ix = new uint[] { 0, 0, 0, 0, 3, 3, 3, 3 };
-			var iy = new uint[] { 1, 1, 4, 4, 1, 1, 4, 4 };
-			var iz = new uint[] { 2, 5, 2, 5, 2, 5, 2, 5 };
-
-			// Vectors to opposing corner
-			var ret = new[]
-			{
-				float.MaxValue, float.MaxValue, float.MaxValue,
-				float.MinValue, float.MinValue, float.MinValue
-			};
-
-			// Transform vectors and find new bounding box
-			for (var i = 0; i < 8; i++)
-			{
-				var vec = new[] { bounds[ix[i]], bounds[iy[i]], bounds[iz[i]], 1 };
-				var tvec = MatrixVectorMultiply(mtx, vec);
-
-				ret[0] = Math.Min(ret[0], tvec[0] / tvec[3]);
-				ret[1] = Math.Min(ret[1], tvec[1] / tvec[3]);
-				ret[2] = Math.Min(ret[2], tvec[2] / tvec[3]);
-				ret[3] = Math.Max(ret[3], tvec[0] / tvec[3]);
-				ret[4] = Math.Max(ret[4], tvec[1] / tvec[3]);
-				ret[5] = Math.Max(ret[5], tvec[2] / tvec[3]);
-			}
-
-			return ret;
-		}
 	}
 }

OpenRA.Game/Graphics/Vertex.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -14,7 +14,7 @@ using System.Runtime.InteropServices;
 namespace OpenRA.Graphics
 {
 	[StructLayout(LayoutKind.Sequential)]
-	public struct Vertex
+	public readonly struct Vertex
 	{
 		// 3d position
 		public readonly float X, Y, Z;
@@ -23,27 +23,42 @@ namespace OpenRA.Graphics
 		public readonly float S, T, U, V;
 
 		// Palette and channel flags
-		public readonly float P, C;
+		public readonly uint C;
 
 		// Color tint
-		public readonly float R, G, B;
+		public readonly float R, G, B, A;
 
-		public Vertex(in float3 xyz, float s, float t, float u, float v, float p, float c)
-			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, p, c, float3.Ones) { }
+		public Vertex(in float3 xyz, float s, float t, float u, float v, uint c)
+			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, c, float3.Ones, 1f) { }
 
-		public Vertex(in float3 xyz, float s, float t, float u, float v, float p, float c, in float3 tint)
-			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, p, c, tint.X, tint.Y, tint.Z) { }
+		public Vertex(in float3 xyz, float s, float t, float u, float v, uint c, in float3 tint, float a)
+			: this(xyz.X, xyz.Y, xyz.Z, s, t, u, v, c, tint.X, tint.Y, tint.Z, a) { }
 
-		public Vertex(float x, float y, float z, float s, float t, float u, float v, float p, float c, in float3 tint)
-			: this(x, y, z, s, t, u, v, p, c, tint.X, tint.Y, tint.Z) { }
+		public Vertex(float x, float y, float z, float s, float t, float u, float v, uint c, in float3 tint, float a)
+			: this(x, y, z, s, t, u, v, c, tint.X, tint.Y, tint.Z, a) { }
 
-		public Vertex(float x, float y, float z, float s, float t, float u, float v, float p, float c, float r, float g, float b)
+		public Vertex(float x, float y, float z, float s, float t, float u, float v, uint c, float r, float g, float b, float a)
 		{
 			X = x; Y = y; Z = z;
 			S = s; T = t;
 			U = u; V = v;
-			P = p; C = c;
-			R = r; G = g; B = b;
+			C = c;
+			R = r; G = g; B = b; A = a;
 		}
 	}
+
+	public sealed class CombinedShaderBindings : ShaderBindings
+	{
+		public CombinedShaderBindings()
+			: base("combined")
+		{ }
+
+		public override ShaderVertexAttribute[] Attributes { get; } = new[]
+		{
+			new ShaderVertexAttribute("aVertexPosition", ShaderVertexAttributeType.Float, 3, 0),
+			new ShaderVertexAttribute("aVertexTexCoord", ShaderVertexAttributeType.Float, 4, 12),
+			new ShaderVertexAttribute("aVertexAttributes", ShaderVertexAttributeType.UInt, 1, 28),
+			new ShaderVertexAttribute("aVertexTint", ShaderVertexAttributeType.Float, 4, 32)
+		};
+	}
 }

OpenRA.Game/Graphics/Video.cs

@@ -0,0 +1,36 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+namespace OpenRA.Video
+{
+	public interface IVideo
+	{
+		ushort FrameCount { get; }
+		byte Framerate { get; }
+		ushort Width { get; }
+		ushort Height { get; }
+
+		/// <summary>
+		/// Current frame color data in 32-bit BGRA.
+		/// </summary>
+		byte[] CurrentFrameData { get; }
+		int CurrentFrameIndex { get; }
+		void AdvanceFrame();
+
+		bool HasAudio { get; }
+		byte[] AudioData { get; }
+		int AudioChannels { get; }
+		int SampleBits { get; }
+		int SampleRate { get; }
+
+		void Reset();
+	}
+}

OpenRA.Game/Graphics/VideoLoader.cs

@@ -0,0 +1,32 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.IO;
+
+namespace OpenRA.Video
+{
+	public interface IVideoLoader
+	{
+		bool TryParseVideo(Stream s, bool useFramePadding, out IVideo video);
+	}
+
+	public static class VideoLoader
+	{
+		public static IVideo GetVideo(Stream stream, bool useFramePadding, IVideoLoader[] loaders)
+		{
+			foreach (var loader in loaders)
+				if (loader.TryParseVideo(stream, useFramePadding, out var video))
+					return video;
+
+			return null;
+		}
+	}
+}

OpenRA.Game/Graphics/Viewport.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -51,11 +51,11 @@ namespace OpenRA.Graphics
 		// Viewport geometry (world-px)
 		public int2 CenterLocation { get; private set; }
 
-		public WPos CenterPosition { get { return worldRenderer.ProjectedPosition(CenterLocation); } }
+		public WPos CenterPosition => worldRenderer.ProjectedPosition(CenterLocation);
 
-		public Rectangle Rectangle { get { return new Rectangle(TopLeft, new Size(viewportSize.X, viewportSize.Y)); } }
-		public int2 TopLeft { get { return CenterLocation - viewportSize / 2; } }
-		public int2 BottomRight { get { return CenterLocation + viewportSize / 2; } }
+		public Rectangle Rectangle => new(TopLeft, new Size(viewportSize.X, viewportSize.Y));
+		public int2 TopLeft => CenterLocation - viewportSize / 2;
+		public int2 BottomRight => CenterLocation + viewportSize / 2;
 		int2 viewportSize;
 		ProjectedCellRegion cells;
 		bool cellsDirty = true;
@@ -66,19 +66,13 @@ namespace OpenRA.Graphics
 		WorldViewport lastViewportDistance;
 
 		float zoom = 1f;
-		float minZoom = 1f;
-		float maxZoom = 2f;
-
 		bool unlockMinZoom;
 		float unlockedMinZoomScale;
 		float unlockedMinZoom = 1f;
 
 		public float Zoom
 		{
-			get
-			{
-				return zoom;
-			}
+			get => zoom;
 
 			private set
 			{
@@ -89,12 +83,13 @@ namespace OpenRA.Graphics
 			}
 		}
 
-		public float MinZoom { get { return minZoom; } }
+		public float MinZoom { get; private set; } = 1f;
+		public float MaxZoom { get; private set; } = 2f;
 
 		public void AdjustZoom(float dz)
 		{
 			// Exponential ensures that equal positive and negative steps have the same effect
-			Zoom = (zoom * (float)Math.Exp(dz)).Clamp(unlockMinZoom ? unlockedMinZoom : minZoom, maxZoom);
+			Zoom = (zoom * (float)Math.Exp(dz)).Clamp(unlockMinZoom ? unlockedMinZoom : MinZoom, MaxZoom);
 		}
 
 		public void AdjustZoom(float dz, int2 center)
@@ -108,10 +103,10 @@ namespace OpenRA.Graphics
 		public void ToggleZoom()
 		{
 			// Unlocked zooms always reset to the default zoom
-			if (zoom < minZoom)
-				Zoom = minZoom;
+			if (zoom < MinZoom)
+				Zoom = MinZoom;
 			else
-				Zoom = zoom > minZoom ? minZoom : maxZoom;
+				Zoom = zoom > MinZoom ? MinZoom : MaxZoom;
 		}
 
 		public void UnlockMinimumZoom(float scale)
@@ -124,23 +119,6 @@ namespace OpenRA.Graphics
 		public static long LastMoveRunTime = 0;
 		public static int2 LastMousePos;
 
-		float ClosestTo(float[] collection, float target)
-		{
-			var closestValue = collection.First();
-			var subtractResult = Math.Abs(closestValue - target);
-
-			foreach (var element in collection)
-			{
-				if (Math.Abs(element - target) < subtractResult)
-				{
-					subtractResult = Math.Abs(element - target);
-					closestValue = element;
-				}
-			}
-
-			return closestValue;
-		}
-
 		public ScrollDirection GetBlockedDirections()
 		{
 			var ret = ScrollDirection.None;
@@ -194,7 +172,7 @@ namespace OpenRA.Graphics
 				UpdateViewportZooms();
 		}
 
-		float CalculateMinimumZoom(float minHeight, float maxHeight)
+		static float CalculateMinimumZoom(float minHeight, float maxHeight)
 		{
 			var h = Game.Renderer.NativeResolution.Height;
 
@@ -230,31 +208,34 @@ namespace OpenRA.Graphics
 
 			var vd = graphicSettings.ViewportDistance;
 			if (viewportSizes.AllowNativeZoom && vd == WorldViewport.Native)
-				minZoom = 1;
+				MinZoom = viewportSizes.DefaultScale;
 			else
 			{
 				var range = viewportSizes.GetSizeRange(vd);
-				minZoom = CalculateMinimumZoom(range.X, range.Y);
+				MinZoom = CalculateMinimumZoom(range.X, range.Y) * viewportSizes.DefaultScale;
 			}
 
-			maxZoom = Math.Min(minZoom * viewportSizes.MaxZoomScale, Game.Renderer.NativeResolution.Height * 1f / viewportSizes.MaxZoomWindowHeight);
+			MaxZoom = Math.Min(MinZoom * viewportSizes.MaxZoomScale, Game.Renderer.NativeResolution.Height * viewportSizes.DefaultScale / viewportSizes.MaxZoomWindowHeight);
 
 			if (unlockMinZoom)
 			{
-				// Specators and the map editor support zooming out by an extra factor of two.
+				// Spectators and the map editor support zooming out by an extra factor of two.
 				// TODO: Allow zooming out until the full map is visible
 				// We need to improve our viewport scroll handling to center the map as we zoom out
 				// before this will work well enough to enable
-				unlockedMinZoom = minZoom * unlockedMinZoomScale;
+				unlockedMinZoom = MinZoom * unlockedMinZoomScale;
 			}
 
 			if (resetCurrentZoom)
-				Zoom = minZoom;
+				Zoom = MinZoom;
 			else
-				Zoom = Zoom.Clamp(minZoom, maxZoom);
+				Zoom = Zoom.Clamp(MinZoom, MaxZoom);
+
+			var maxSize = 1f / (unlockMinZoom ? unlockedMinZoom : MinZoom) * new float2(Game.Renderer.NativeResolution);
+			Game.Renderer.SetMaximumViewportSize(new Size((int)maxSize.X, (int)maxSize.Y));
 
 			foreach (var t in worldRenderer.World.WorldActor.TraitsImplementing<INotifyViewportZoomExtentsChanged>())
-				t.ViewportZoomExtentsChanged(minZoom, maxZoom);
+				t.ViewportZoomExtentsChanged(MinZoom, MaxZoom);
 		}
 
 		public CPos ViewToWorld(int2 view)
@@ -297,15 +278,27 @@ namespace OpenRA.Graphics
 			return worldRenderer.World.Map.CellContaining(worldRenderer.ProjectedPosition(ViewToWorldPx(view)));
 		}
 
-		/// <summary> Returns an unfiltered list of all cells that could potentially contain the mouse cursor</summary>
+		/// <summary>Returns an unfiltered list of all cells that could potentially contain the mouse cursor.</summary>
 		IEnumerable<MPos> CandidateMouseoverCells(int2 world)
 		{
 			var map = worldRenderer.World.Map;
+			var tileScale = map.Grid.TileScale / 2;
 			var minPos = worldRenderer.ProjectedPosition(world);
 
-			// Find all the cells that could potentially have been clicked
-			var a = map.CellContaining(minPos - new WVec(1024, 0, 0)).ToMPos(map.Grid.Type);
-			var b = map.CellContaining(minPos + new WVec(512, 512 * map.Grid.MaximumTerrainHeight, 0)).ToMPos(map.Grid.Type);
+			// Find all the cells that could potentially have been clicked.
+			MPos a;
+			MPos b;
+			if (map.Grid.Type == MapGridType.RectangularIsometric)
+			{
+				// TODO: this generates too many cells.
+				a = map.CellContaining(minPos - new WVec(tileScale, 0, 0)).ToMPos(map.Grid.Type);
+				b = map.CellContaining(minPos + new WVec(tileScale, tileScale * map.Grid.MaximumTerrainHeight, 0)).ToMPos(map.Grid.Type);
+			}
+			else
+			{
+				a = map.CellContaining(minPos).ToMPos(map.Grid.Type);
+				b = map.CellContaining(minPos + new WVec(0, tileScale * map.Grid.MaximumTerrainHeight, 0)).ToMPos(map.Grid.Type);
+			}
 
 			for (var v = b.V; v >= a.V; v--)
 				for (var u = b.U; u >= a.U; u--)
@@ -313,15 +306,18 @@ namespace OpenRA.Graphics
 		}
 
 		public int2 ViewToWorldPx(int2 view) { return (graphicSettings.UIScale / Zoom * view.ToFloat2()).ToInt2() + TopLeft; }
-		public int2 WorldToViewPx(int2 world) { return ((Zoom / graphicSettings.UIScale) * (world - TopLeft).ToFloat2()).ToInt2(); }
-		public int2 WorldToViewPx(in float3 world) { return ((Zoom / graphicSettings.UIScale) * (world - TopLeft).XY).ToInt2(); }
+		public int2 WorldToViewPx(int2 world) { return (Zoom / graphicSettings.UIScale * (world - TopLeft).ToFloat2()).ToInt2(); }
+		public int2 WorldToViewPx(in float3 world) { return (Zoom / graphicSettings.UIScale * (world - TopLeft).XY).ToInt2(); }
 
 		public void Center(IEnumerable<Actor> actors)
 		{
-			if (!actors.Any())
+			var actorsCollection = actors as IReadOnlyCollection<Actor>;
+			actorsCollection ??= actors.ToList();
+
+			if (actorsCollection.Count == 0)
 				return;
 
-			Center(actors.Select(a => a.CenterPosition).Average());
+			Center(actorsCollection.Select(a => a.CenterPosition).Average());
 		}
 
 		public void Center(WPos pos)

OpenRA.Game/Graphics/WorldRenderer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -21,38 +21,37 @@ namespace OpenRA.Graphics
 	public sealed class WorldRenderer : IDisposable
 	{
 		public static readonly Func<IRenderable, int> RenderableZPositionComparisonKey =
-			r => ZPosition(r.Pos, r.ZOffset);
+			r => r.Pos.Y + r.Pos.Z + r.ZOffset;
 
 		public readonly Size TileSize;
 		public readonly int TileScale;
 		public readonly World World;
-		public readonly Theater Theater;
-		public Viewport Viewport { get; private set; }
+		public Viewport Viewport { get; }
 		public readonly ITerrainLighting TerrainLighting;
 
 		public event Action PaletteInvalidated = null;
 
-		readonly HashSet<Actor> onScreenActors = new HashSet<Actor>();
-		readonly HardwarePalette palette = new HardwarePalette();
-		readonly Dictionary<string, PaletteReference> palettes = new Dictionary<string, PaletteReference>();
+		readonly HashSet<Actor> onScreenActors = new();
+		readonly HardwarePalette palette = new();
+		readonly Dictionary<string, PaletteReference> palettes = new();
 		readonly IRenderTerrain terrainRenderer;
 		readonly Lazy<DebugVisualizations> debugVis;
 		readonly Func<string, PaletteReference> createPaletteReference;
 		readonly bool enableDepthBuffer;
 
-		readonly List<IFinalizedRenderable> preparedRenderables = new List<IFinalizedRenderable>();
-		readonly List<IFinalizedRenderable> preparedOverlayRenderables = new List<IFinalizedRenderable>();
-		readonly List<IFinalizedRenderable> preparedAnnotationRenderables = new List<IFinalizedRenderable>();
+		readonly List<IFinalizedRenderable> preparedRenderables = new();
+		readonly List<IFinalizedRenderable> preparedOverlayRenderables = new();
+		readonly List<IFinalizedRenderable> preparedAnnotationRenderables = new();
 
-		readonly List<IRenderable> renderablesBuffer = new List<IRenderable>();
-
-		bool lastDepthPreviewEnabled;
+		readonly List<IRenderable> renderablesBuffer = new();
+		readonly IRenderer[] renderers;
+		readonly IRenderPostProcessPass[] postProcessPasses;
 
 		internal WorldRenderer(ModData modData, World world)
 		{
 			World = world;
 			TileSize = World.Map.Grid.TileSize;
-			TileScale = World.Map.Grid.Type == MapGridType.RectangularIsometric ? 1448 : 1024;
+			TileScale = World.Map.Grid.TileScale;
 			Viewport = new Viewport(this, world.Map);
 
 			createPaletteReference = CreatePaletteReference;
@@ -68,11 +67,25 @@ namespace OpenRA.Graphics
 
 			palette.Initialize();
 
-			Theater = new Theater(world.Map.Rules.TileSet);
 			TerrainLighting = world.WorldActor.TraitOrDefault<ITerrainLighting>();
+			renderers = world.WorldActor.TraitsImplementing<IRenderer>().ToArray();
 			terrainRenderer = world.WorldActor.TraitOrDefault<IRenderTerrain>();
 
 			debugVis = Exts.Lazy(() => world.WorldActor.TraitOrDefault<DebugVisualizations>());
+
+			postProcessPasses = world.WorldActor.TraitsImplementing<IRenderPostProcessPass>().ToArray();
+		}
+
+		public void BeginFrame()
+		{
+			foreach (var r in renderers)
+				r.BeginFrame();
+		}
+
+		public void EndFrame()
+		{
+			foreach (var r in renderers)
+				r.EndFrame();
 		}
 
 		public void UpdatePalettesForPlayer(string internalName, Color color, bool replaceExisting)
@@ -87,7 +100,13 @@ namespace OpenRA.Graphics
 			return new PaletteReference(name, palette.GetPaletteIndex(name), pal, palette);
 		}
 
-		public PaletteReference Palette(string name) { return palettes.GetOrAdd(name, createPaletteReference); }
+		public PaletteReference Palette(string name)
+		{
+			// HACK: This is working around the fact that palettes are defined on traits rather than sequences
+			// and can be removed once this has been fixed.
+			return string.IsNullOrEmpty(name) ? null : palettes.GetOrAdd(name, createPaletteReference);
+		}
+
 		public void AddPalette(string name, ImmutablePalette pal, bool allowModifiers = false, bool allowOverwrite = false)
 		{
 			if (allowOverwrite && palette.Contains(name))
@@ -107,8 +126,13 @@ namespace OpenRA.Graphics
 			palette.ReplacePalette(name, pal);
 
 			// Update cached PlayerReference if one exists
-			if (palettes.ContainsKey(name))
-				palettes[name].Palette = pal;
+			if (palettes.TryGetValue(name, out var paletteReference))
+				paletteReference.Palette = pal;
+		}
+
+		public void SetPaletteColorShift(string name, float hueOffset, float satOffset, float valueModifier, float minHue, float maxHue)
+		{
+			palette.SetColorShift(name, hueOffset, satOffset, valueModifier, minHue, maxHue);
 		}
 
 		// PERF: Avoid LINQ.
@@ -144,14 +168,14 @@ namespace OpenRA.Graphics
 		// PERF: Avoid LINQ.
 		void GenerateOverlayRenderables()
 		{
-			foreach (var a in World.ActorsWithTrait<IRenderAboveShroud>())
+			World.ApplyToActorsWithTrait<IRenderAboveShroud>((actor, trait) =>
 			{
-				if (!a.Actor.IsInWorld || a.Actor.Disposed || (a.Trait.SpatiallyPartitionable && !onScreenActors.Contains(a.Actor)))
-					continue;
+				if (!actor.IsInWorld || actor.Disposed || (trait.SpatiallyPartitionable && !onScreenActors.Contains(actor)))
+					return;
 
-				foreach (var renderable in a.Trait.RenderAboveShroud(a.Actor, this))
+				foreach (var renderable in trait.RenderAboveShroud(actor, this))
 					preparedOverlayRenderables.Add(renderable.PrepareRender(this));
-			}
+			});
 
 			foreach (var a in World.Selection.Actors)
 			{
@@ -170,8 +194,7 @@ namespace OpenRA.Graphics
 
 			foreach (var e in World.Effects)
 			{
-				var ea = e as IEffectAboveShroud;
-				if (ea == null)
+				if (e is not IEffectAboveShroud ea)
 					continue;
 
 				foreach (var renderable in ea.RenderAboveShroud(this))
@@ -186,14 +209,14 @@ namespace OpenRA.Graphics
 		// PERF: Avoid LINQ.
 		void GenerateAnnotationRenderables()
 		{
-			foreach (var a in World.ActorsWithTrait<IRenderAnnotations>())
+			World.ApplyToActorsWithTrait<IRenderAnnotations>((actor, trait) =>
 			{
-				if (!a.Actor.IsInWorld || a.Actor.Disposed || (a.Trait.SpatiallyPartitionable && !onScreenActors.Contains(a.Actor)))
-					continue;
+				if (!actor.IsInWorld || actor.Disposed || (trait.SpatiallyPartitionable && !onScreenActors.Contains(actor)))
+					return;
 
-				foreach (var renderAnnotation in a.Trait.RenderAnnotations(a.Actor, this))
+				foreach (var renderAnnotation in trait.RenderAnnotations(actor, this))
 					preparedAnnotationRenderables.Add(renderAnnotation.PrepareRender(this));
-			}
+			});
 
 			foreach (var a in World.Selection.Actors)
 			{
@@ -212,8 +235,7 @@ namespace OpenRA.Graphics
 
 			foreach (var e in World.Effects)
 			{
-				var ea = e as IEffectAnnotation;
-				if (ea == null)
+				if (e is not IEffectAnnotation ea)
 					continue;
 
 				foreach (var renderAnnotation in ea.RenderAnnotation(this))
@@ -247,11 +269,7 @@ namespace OpenRA.Graphics
 			if (World.WorldActor.Disposed)
 				return;
 
-			if (debugVis.Value != null && lastDepthPreviewEnabled != debugVis.Value.DepthBuffer)
-			{
-				lastDepthPreviewEnabled = debugVis.Value.DepthBuffer;
-				Game.Renderer.WorldSpriteRenderer.SetDepthPreviewEnabled(lastDepthPreviewEnabled);
-			}
+			debugVis.Value?.UpdateDepthBuffer();
 
 			var bounds = Viewport.GetScissorBounds(World.Type != WorldType.Editor);
 			Game.Renderer.EnableScissor(bounds);
@@ -269,15 +287,20 @@ namespace OpenRA.Graphics
 			if (enableDepthBuffer)
 				Game.Renderer.ClearDepthBuffer();
 
-			foreach (var a in World.ActorsWithTrait<IRenderAboveWorld>())
-				if (a.Actor.IsInWorld && !a.Actor.Disposed)
-					a.Trait.RenderAboveWorld(a.Actor, this);
+			ApplyPostProcessing(PostProcessPassType.AfterActors);
+
+			World.ApplyToActorsWithTrait<IRenderAboveWorld>((actor, trait) =>
+			{
+				if (actor.IsInWorld && !actor.Disposed)
+					trait.RenderAboveWorld(actor, this);
+			});
 
 			if (enableDepthBuffer)
 				Game.Renderer.ClearDepthBuffer();
 
-			foreach (var a in World.ActorsWithTrait<IRenderShroud>())
-				a.Trait.RenderShroud(this);
+			ApplyPostProcessing(PostProcessPassType.AfterWorld);
+
+			World.ApplyToActorsWithTrait<IRenderShroud>((actor, trait) => trait.RenderShroud(this));
 
 			if (enableDepthBuffer)
 				Game.Renderer.Context.DisableDepthBuffer();
@@ -290,9 +313,23 @@ namespace OpenRA.Graphics
 				foreach (var r in g)
 					r.Render(this);
 
+			ApplyPostProcessing(PostProcessPassType.AfterShroud);
+
 			Game.Renderer.Flush();
 		}
 
+		void ApplyPostProcessing(PostProcessPassType type)
+		{
+			foreach (var pass in postProcessPasses)
+			{
+				if (pass.Type != type || !pass.Enabled)
+					continue;
+
+				Game.Renderer.Flush();
+				pass.Draw(this);
+			}
+		}
+
 		public void DrawAnnotations()
 		{
 			Game.Renderer.EnableAntialiasingFilter();
@@ -356,7 +393,13 @@ namespace OpenRA.Graphics
 
 		public float3 Screen3DPosition(WPos pos)
 		{
-			var z = ZPosition(pos, 0) * (float)TileSize.Height / TileScale;
+			// The projection from world coordinates to screen coordinates has
+			// a non-obvious relationship between the y and z coordinates:
+			// * A flat surface with constant y (e.g. a vertical wall) in world coordinates
+			//   transforms into a flat surface with constant z (depth) in screen coordinates.
+			// * Increasing the world y coordinate increases screen y and z coordinates equally.
+			// * Increases the world z coordinate decreases screen y but doesn't change screen z.
+			var z = pos.Y * (float)TileSize.Height / TileScale;
 			return new float3((float)TileSize.Width * pos.X / TileScale, (float)TileSize.Height * (pos.Y - pos.Z) / TileScale, z);
 		}
 
@@ -375,7 +418,7 @@ namespace OpenRA.Graphics
 		}
 
 		// For scaling vectors to pixel sizes in the model renderer
-		public float3 ScreenVectorComponents(WVec vec)
+		public float3 ScreenVectorComponents(in WVec vec)
 		{
 			return new float3(
 				(float)TileSize.Width * vec.X / TileScale,
@@ -384,29 +427,19 @@ namespace OpenRA.Graphics
 		}
 
 		// For scaling vectors to pixel sizes in the model renderer
-		public float[] ScreenVector(WVec vec)
+		public float[] ScreenVector(in WVec vec)
 		{
 			var xyz = ScreenVectorComponents(vec);
 			return new[] { xyz.X, xyz.Y, xyz.Z, 1f };
 		}
 
-		public int2 ScreenPxOffset(WVec vec)
+		public int2 ScreenPxOffset(in WVec vec)
 		{
 			// Round to nearest pixel
 			var xyz = ScreenVectorComponents(vec);
 			return new int2((int)Math.Round(xyz.X), (int)Math.Round(xyz.Y));
 		}
 
-		public float ScreenZPosition(WPos pos, int offset)
-		{
-			return ZPosition(pos, offset) * (float)TileSize.Height / TileScale;
-		}
-
-		static int ZPosition(WPos pos, int offset)
-		{
-			return pos.Y + pos.Z + offset;
-		}
-
 		/// <summary>
 		/// Returns a position in the world that is projected to the given screen position.
 		/// There are many possible world positions, and the returned value chooses the value with no elevation.
@@ -425,7 +458,6 @@ namespace OpenRA.Graphics
 			World.Dispose();
 
 			palette.Dispose();
-			Theater.Dispose();
 		}
 	}
 }

OpenRA.Game/HotkeyDefinition.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -10,7 +10,6 @@
 #endregion
 
 using System.Collections.Generic;
-using System.Linq;
 
 namespace OpenRA
 {
@@ -19,7 +18,9 @@ namespace OpenRA
 		public readonly string Name;
 		public readonly Hotkey Default = Hotkey.Invalid;
 		public readonly string Description = "";
-		public readonly HashSet<string> Types = new HashSet<string>();
+		public readonly HashSet<string> Types = new();
+		public readonly HashSet<string> Contexts = new();
+		public readonly bool Readonly = false;
 		public bool HasDuplicates { get; internal set; }
 
 		public HotkeyDefinition(string name, MiniYaml node)
@@ -29,13 +30,26 @@ namespace OpenRA
 			if (!string.IsNullOrEmpty(node.Value))
 				Default = FieldLoader.GetValue<Hotkey>("value", node.Value);
 
-			var descriptionNode = node.Nodes.FirstOrDefault(n => n.Key == "Description");
-			if (descriptionNode != null)
-				Description = descriptionNode.Value.Value;
+			var nodeDict = node.ToDictionary();
 
-			var typesNode = node.Nodes.FirstOrDefault(n => n.Key == "Types");
-			if (typesNode != null)
-				Types = FieldLoader.GetValue<HashSet<string>>("Types", typesNode.Value.Value);
+			if (nodeDict.TryGetValue("Description", out var descriptionYaml))
+				Description = descriptionYaml.Value;
+
+			if (nodeDict.TryGetValue("Types", out var typesYaml))
+				Types = FieldLoader.GetValue<HashSet<string>>("Types", typesYaml.Value);
+
+			if (nodeDict.TryGetValue("Contexts", out var contextYaml))
+				Contexts = FieldLoader.GetValue<HashSet<string>>("Contexts", contextYaml.Value);
+
+			if (nodeDict.TryGetValue("Platform", out var platformYaml))
+			{
+				var platformOverride = platformYaml.NodeWithKeyOrDefault(Platform.CurrentPlatform.ToString());
+				if (platformOverride != null)
+					Default = FieldLoader.GetValue<Hotkey>("value", platformOverride.Value.Value);
+			}
+
+			if (nodeDict.TryGetValue("Readonly", out var readonlyYaml))
+				Readonly = FieldLoader.GetValue<bool>("Readonly", readonlyYaml.Value);
 		}
 	}
 }

OpenRA.Game/HotkeyManager.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -18,8 +18,8 @@ namespace OpenRA
 	public sealed class HotkeyManager
 	{
 		readonly Dictionary<string, Hotkey> settings;
-		readonly Dictionary<string, HotkeyDefinition> definitions = new Dictionary<string, HotkeyDefinition>();
-		readonly Dictionary<string, Hotkey> keys = new Dictionary<string, Hotkey>();
+		readonly Dictionary<string, HotkeyDefinition> definitions = new();
+		readonly Dictionary<string, Hotkey> keys = new();
 
 		public HotkeyManager(IReadOnlyFileSystem fileSystem, Dictionary<string, Hotkey> settings, Manifest manifest)
 		{
@@ -35,14 +35,17 @@ namespace OpenRA
 
 			foreach (var kv in settings)
 			{
-				if (definitions.ContainsKey(kv.Key))
+				if (definitions.TryGetValue(kv.Key, out var definition) && !definition.Readonly)
 					keys[kv.Key] = kv.Value;
 			}
 
 			foreach (var hd in definitions)
-				hd.Value.HasDuplicates = GetFirstDuplicate(hd.Value.Name, this[hd.Value.Name].GetValue(), hd.Value) != null;
+				hd.Value.HasDuplicates = GetFirstDuplicate(hd.Value, this[hd.Value.Name].GetValue()) != null;
 		}
 
+		[System.Diagnostics.CodeAnalysis.SuppressMessage(
+			"Performance", "CA1854:Prefer the 'IDictionary.TryGetValue(TKey, out TValue)' method",
+			Justification = "Func must perform a live lookup in the collection, as the lookup value can change.")]
 		internal Func<Hotkey> GetHotkeyReference(string name)
 		{
 			// Is this a mod-defined hotkey?
@@ -61,6 +64,9 @@ namespace OpenRA
 			if (!definitions.TryGetValue(name, out var definition))
 				return;
 
+			if (definition.Readonly)
+				return;
+
 			keys[name] = value;
 			if (value != definition.Default)
 				settings[name] = value;
@@ -68,7 +74,7 @@ namespace OpenRA
 				settings.Remove(name);
 
 			var hadDuplicates = definition.HasDuplicates;
-			definition.HasDuplicates = GetFirstDuplicate(definition.Name, this[definition.Name].GetValue(), definition) != null;
+			definition.HasDuplicates = GetFirstDuplicate(definition, this[definition.Name].GetValue()) != null;
 
 			if (hadDuplicates || definition.HasDuplicates)
 			{
@@ -77,33 +83,30 @@ namespace OpenRA
 					if (hd.Value == definition)
 						continue;
 
-					hd.Value.HasDuplicates = GetFirstDuplicate(hd.Value.Name, this[hd.Value.Name].GetValue(), hd.Value) != null;
+					hd.Value.HasDuplicates = GetFirstDuplicate(hd.Value, this[hd.Value.Name].GetValue()) != null;
 				}
 			}
 		}
 
-		public HotkeyDefinition GetFirstDuplicate(string name, Hotkey value, HotkeyDefinition definition)
+		public HotkeyDefinition GetFirstDuplicate(HotkeyDefinition definition, Hotkey value)
 		{
+			if (definition == null)
+				return null;
+
 			foreach (var kv in keys)
 			{
-				if (kv.Key == name)
+				if (kv.Key == definition.Name)
 					continue;
 
-				if (kv.Value == value && definitions[kv.Key].Types.Overlaps(definition.Types))
+				if (kv.Value == value && definitions[kv.Key].Contexts.Overlaps(definition.Contexts))
 					return definitions[kv.Key];
 			}
 
 			return null;
 		}
 
-		public HotkeyReference this[string name]
-		{
-			get
-			{
-				return new HotkeyReference(GetHotkeyReference(name));
-			}
-		}
+		public HotkeyReference this[string name] => new(GetHotkeyReference(name));
 
-		public IEnumerable<HotkeyDefinition> Definitions { get { return definitions.Values; } }
+		public IEnumerable<HotkeyDefinition> Definitions => definitions.Values;
 	}
 }

OpenRA.Game/HttpExtension.cs

@@ -0,0 +1,63 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.IO;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace OpenRA
+{
+	public delegate void OnProgress(long total, long totalRead, int progressPercentage);
+
+	public static class HttpExtension
+	{
+		public static async Task ReadAsStreamWithProgress(this HttpResponseMessage response, Stream outputStream, OnProgress onProgress, CancellationToken token)
+		{
+			var total = response.Content.Headers.ContentLength ?? -1;
+			var canReportProgress = total > 0;
+
+#if NET5_0_OR_GREATER
+			using (var contentStream = await response.Content.ReadAsStreamAsync(token))
+#else
+			using (var contentStream = await response.Content.ReadAsStreamAsync())
+#endif
+			{
+				var totalRead = 0L;
+				var buffer = new byte[8192];
+				var hasMoreToRead = true;
+
+				do
+				{
+					var read = await contentStream.ReadAsync(buffer.AsMemory(0, buffer.Length), token);
+					if (read == 0)
+						hasMoreToRead = false;
+					else
+					{
+						await outputStream.WriteAsync(buffer.AsMemory(0, read), token);
+
+						totalRead += read;
+
+						if (canReportProgress)
+						{
+							var progressPercentage = (int)((double)totalRead / total * 100);
+							onProgress?.Invoke(total, totalRead, progressPercentage);
+						}
+					}
+				}
+				while (hasMoreToRead && !token.IsCancellationRequested);
+
+				onProgress?.Invoke(total, totalRead, 100);
+			}
+		}
+	}
+}

OpenRA.Game/IUtilityCommand.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -9,12 +9,41 @@
  */
 #endregion
 
+using System;
+using System.Reflection;
+using OpenRA.Primitives;
 using OpenRA.Traits;
 
 namespace OpenRA
 {
 	public class Utility
 	{
+		static readonly ConcurrentCache<Type, FieldInfo[]> TypeFields =
+			new(type => type.GetFields());
+
+		static readonly ConcurrentCache<(MemberInfo Member, Type AttributeType), bool> MemberHasAttribute =
+			new(x => Attribute.IsDefined(x.Member, x.AttributeType));
+
+		static readonly ConcurrentCache<(MemberInfo Member, Type AttributeType, bool Inherit), object[]> MemberCustomAttributes =
+			new(x => x.Member.GetCustomAttributes(x.AttributeType, x.Inherit));
+
+		public static FieldInfo[] GetFields(Type type)
+		{
+			return TypeFields[type];
+		}
+
+		public static bool HasAttribute<TAttribute>(MemberInfo member)
+			where TAttribute : Attribute
+		{
+			return MemberHasAttribute[(member, typeof(TAttribute))];
+		}
+
+		public static TAttribute[] GetCustomAttributes<TAttribute>(MemberInfo member, bool inherit)
+			where TAttribute : Attribute
+		{
+			return (TAttribute[])MemberCustomAttributes[(member, typeof(TAttribute), inherit)];
+		}
+
 		public readonly ModData ModData;
 		public readonly InstalledMods Mods;
 

OpenRA.Game/Input/Hotkey.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -13,9 +13,9 @@ using System;
 
 namespace OpenRA
 {
-	public struct Hotkey : IEquatable<Hotkey>
+	public readonly struct Hotkey : IEquatable<Hotkey>
 	{
-		public static Hotkey Invalid = new Hotkey(Keycode.UNKNOWN, Modifiers.None);
+		public static Hotkey Invalid = new(Keycode.UNKNOWN, Modifiers.None);
 		public bool IsValid()
 		{
 			return Key != Keycode.UNKNOWN;
@@ -42,7 +42,7 @@ namespace OpenRA
 			var mods = Modifiers.None;
 			if (parts.Length >= 2)
 			{
-				var modString = s.Substring(s.IndexOf(' '));
+				var modString = s[s.IndexOf(' ')..];
 				if (!Enum<Modifiers>.TryParse(modString, true, out mods))
 					return false;
 			}
@@ -81,11 +81,10 @@ namespace OpenRA
 
 		public override bool Equals(object obj)
 		{
-			var o = obj as Hotkey?;
-			return o != null && o == this;
+			return obj is Hotkey o && (Hotkey?)o == this;
 		}
 
-		public override string ToString() { return "{0} {1}".F(Key, Modifiers.ToString("F")); }
+		public override string ToString() { return $"{Key} {Modifiers:F}"; }
 
 		public string DisplayString()
 		{

OpenRA.Game/Input/HotkeyReference.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -14,7 +14,7 @@ using System;
 namespace OpenRA
 {
 	/// <summary>
-	/// A reference to either a named hotkey (defined in the game settings) or a statically assigned hotkey
+	/// A reference to either a named hotkey (defined in the game settings) or a statically assigned hotkey.
 	/// </summary>
 	public class HotkeyReference
 	{

OpenRA.Game/Input/IInputHandler.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of

OpenRA.Game/Input/InputHandler.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -37,36 +37,24 @@ namespace OpenRA
 
 		public void OnKeyInput(KeyInput input)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleKeyPress(input));
+			Sync.RunUnsynced(world, () => Ui.HandleKeyPress(input));
 		}
 
 		public void OnTextInput(string text)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleTextInput(text));
+			Sync.RunUnsynced(world, () => Ui.HandleTextInput(text));
 		}
 
 		public void OnMouseInput(MouseInput input)
 		{
-			Sync.RunUnsynced(Game.Settings.Debug.SyncCheckUnsyncedCode, world, () => Ui.HandleInput(input));
+			Sync.RunUnsynced(world, () => Ui.HandleInput(input));
 		}
 	}
 
 	public class MouseButtonPreference
 	{
-		public MouseButton Action
-		{
-			get
-			{
-				return Game.Settings.Game.UseClassicMouseStyle ? MouseButton.Left : MouseButton.Right;
-			}
-		}
+		public MouseButton Action => Game.Settings.Game.UseClassicMouseStyle ? MouseButton.Left : MouseButton.Right;
 
-		public MouseButton Cancel
-		{
-			get
-			{
-				return Game.Settings.Game.UseClassicMouseStyle ? MouseButton.Right : MouseButton.Left;
-			}
-		}
+		public MouseButton Cancel => Game.Settings.Game.UseClassicMouseStyle ? MouseButton.Right : MouseButton.Left;
 	}
 }

OpenRA.Game/Input/Keycode.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -13,7 +13,8 @@ using System.Collections.Generic;
 
 namespace OpenRA
 {
-	// List of keycodes, duplicated from SDL 2.0.1
+	// List of keycodes. Duplicated from SDL 2.0.1, with the addition
+	// of MOUSE4 and MOUSE5.
 	public enum Keycode
 	{
 		UNKNOWN = 0,
@@ -252,11 +253,13 @@ namespace OpenRA
 		KBDILLUMUP = 280 | (1 << 30),
 		EJECT = 281 | (1 << 30),
 		SLEEP = 282 | (1 << 30),
+		MOUSE4 = 283 | (1 << 30),
+		MOUSE5 = 284 | (1 << 30)
 	}
 
 	public static class KeycodeExts
 	{
-		static readonly Dictionary<Keycode, string> KeyNames = new Dictionary<Keycode, string>
+		static readonly Dictionary<Keycode, string> KeyNames = new()
 		{
 			{ Keycode.UNKNOWN, "Undefined" },
 			{ Keycode.RETURN, "Return" },
@@ -494,6 +497,8 @@ namespace OpenRA
 			{ Keycode.KBDILLUMUP, "KBDIllumUp" },
 			{ Keycode.EJECT, "Eject" },
 			{ Keycode.SLEEP, "Sleep" },
+			{ Keycode.MOUSE4, "Mouse 4" },
+			{ Keycode.MOUSE5, "Mouse 5" },
 		};
 
 		public static string DisplayString(Keycode k)

OpenRA.Game/InstalledMods.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -15,22 +15,18 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using OpenRA.FileSystem;
-using OpenRA.Graphics;
-using OpenRA.Primitives;
 
 namespace OpenRA
 {
 	public class InstalledMods : IReadOnlyDictionary<string, Manifest>
 	{
 		readonly Dictionary<string, Manifest> mods;
-		readonly SheetBuilder sheetBuilder;
 
 		/// <summary>Initializes the collection of locally installed mods.</summary>
 		/// <param name="searchPaths">Filesystem paths to search for mod packages.</param>
 		/// <param name="explicitPaths">Filesystem paths to additional mod packages.</param>
 		public InstalledMods(IEnumerable<string> searchPaths, IEnumerable<string> explicitPaths)
 		{
-			sheetBuilder = new SheetBuilder(SheetType.BGRA, 256);
 			mods = GetInstalledMods(searchPaths, explicitPaths);
 		}
 
@@ -58,7 +54,7 @@ namespace OpenRA
 			return mods;
 		}
 
-		Manifest LoadMod(string id, string path)
+		static Manifest LoadMod(string id, string path)
 		{
 			IReadOnlyPackage package = null;
 			try
@@ -75,7 +71,7 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Log.Write("debug", "Load mod '{0}': {1}".F(path, e));
+				Log.Write("debug", $"Load mod '{path}': {e}");
 			}
 
 			package?.Dispose();
@@ -83,7 +79,7 @@ namespace OpenRA
 			return null;
 		}
 
-		Dictionary<string, Manifest> GetInstalledMods(IEnumerable<string> searchPaths, IEnumerable<string> explicitPaths)
+		static Dictionary<string, Manifest> GetInstalledMods(IEnumerable<string> searchPaths, IEnumerable<string> explicitPaths)
 		{
 			var ret = new Dictionary<string, Manifest>();
 			var candidates = GetCandidateMods(searchPaths)
@@ -99,10 +95,10 @@ namespace OpenRA
 			return ret;
 		}
 
-		public Manifest this[string key] { get { return mods[key]; } }
-		public int Count { get { return mods.Count; } }
-		public ICollection<string> Keys { get { return mods.Keys; } }
-		public ICollection<Manifest> Values { get { return mods.Values; } }
+		public Manifest this[string key] => mods[key];
+		public IEnumerable<string> Keys => mods.Keys;
+		public IEnumerable<Manifest> Values => mods.Values;
+		public int Count => mods.Count;
 		public bool ContainsKey(string key) { return mods.ContainsKey(key); }
 		public IEnumerator<KeyValuePair<string, Manifest>> GetEnumerator() { return mods.GetEnumerator(); }
 		public bool TryGetValue(string key, out Manifest value) { return mods.TryGetValue(key, out value); }

OpenRA.Game/LocalPlayerProfile.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * Copyright (c) The OpenRA Developers and Contributors
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation, either version 3 of
@@ -12,10 +12,10 @@
 using System;
 using System.IO;
 using System.Linq;
-using System.Net;
 using System.Security.Cryptography;
 using System.Text;
 using System.Threading.Tasks;
+using OpenRA.Support;
 
 namespace OpenRA
 {
@@ -24,11 +24,11 @@ namespace OpenRA
 		const int AuthKeySize = 2048;
 		public enum LinkState { Uninitialized, GeneratingKeys, Unlinked, CheckingLink, ConnectionFailed, Linked }
 
-		public LinkState State { get { return innerState; } }
-		public string Fingerprint { get { return innerFingerprint; } }
-		public string PublicKey { get { return innerPublicKey; } }
+		public LinkState State => innerState;
+		public string Fingerprint => innerFingerprint;
+		public string PublicKey => innerPublicKey;
 
-		public PlayerProfile ProfileData { get { return innerData; } }
+		public PlayerProfile ProfileData => innerData;
 
 		volatile LinkState innerState;
 		volatile PlayerProfile innerData;
@@ -66,8 +66,10 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Console.WriteLine("Failed to load keys: {0}", e);
-				Log.Write("debug", "Failed to load player keypair from `{0}` with exception: {1}", filePath, e);
+				Console.WriteLine("Failed to load keys:");
+				Console.WriteLine(e);
+				Log.Write("debug", $"Failed to load player keypair from `{filePath}` with exception:");
+				Log.Write("debug", e);
 			}
 		}
 
@@ -76,23 +78,23 @@ namespace OpenRA
 			if (State != LinkState.Unlinked && State != LinkState.Linked && State != LinkState.ConnectionFailed)
 				return;
 
-			Action<DownloadDataCompletedEventArgs> onQueryComplete = i =>
+			Task.Run(async () =>
 			{
 				try
 				{
-					if (i.Error != null)
-					{
-						innerState = LinkState.ConnectionFailed;
-						return;
-					}
+					var client = HttpClientFactory.Create();
 
-					var yaml = MiniYaml.FromString(Encoding.UTF8.GetString(i.Result)).First();
+					var url = playerDatabase.Profile + Fingerprint;
+					var httpResponseMessage = await client.GetAsync(url);
+					var result = await httpResponseMessage.Content.ReadAsStreamAsync();
+
+					var yaml = MiniYaml.FromStream(result, url).First();
 					if (yaml.Key == "Player")
 					{
 						innerData = FieldLoader.Load<PlayerProfile>(yaml.Value);
 						if (innerData.KeyRevoked)
 						{
-							Log.Write("debug", "Revoking key with fingerprint {0}", Fingerprint);
+							Log.Write("debug", $"Revoking key with fingerprint {Fingerprint}");
 							DeleteKeypair();
 						}
 						else
@@ -103,17 +105,17 @@ namespace OpenRA
 				}
 				catch (Exception e)
 				{
-					Log.Write("debug", "Failed to parse player data result with exception: {0}", e);
+					Log.Write("debug", "Failed to parse player data result with exception:");
+					Log.Write("debug", e);
 					innerState = LinkState.ConnectionFailed;
 				}
 				finally
 				{
 					onComplete?.Invoke();
 				}
-			};
+			});
 
 			innerState = LinkState.CheckingLink;
-			new Download(playerDatabase.Profile + Fingerprint, _ => { }, onQueryComplete);
 		}
 
 		public void GenerateKeypair()
@@ -138,8 +140,10 @@ namespace OpenRA
 				}
 				catch (Exception e)
 				{
-					Log.Write("debug", "Failed to generate keypair with exception: {1}", e);
-					Console.WriteLine("Key generation failed: {0}", e);
+					Log.Write("debug", "Failed to generate keypair with exception:");
+					Log.Write("debug", e);
+					Console.WriteLine("Key generation failed:");
+					Console.WriteLine(e);
 
 					innerState = LinkState.Uninitialized;
 				}
@@ -154,12 +158,14 @@ namespace OpenRA
 			}
 			catch (Exception e)
 			{
-				Log.Write("debug", "Failed to delete keypair with exception: {1}", e);
-				Console.WriteLine("Key deletion failed: {0}", e);
+				Log.Write("debug", "Failed to delete keypair with exception:");
+				Log.Write("debug", e);
+				Console.WriteLine("Key deletion failed:");
+				Console.WriteLine(e);
 			}
 
 			innerState = LinkState.Uninitialized;
-			parameters = default(RSAParameters);
+			parameters = default;
 			innerFingerprint = null;
 			innerData = null;
 		}