diff --git a/glide3x/h3/glide3/src/xdrawtri.asm b/glide3x/h3/glide3/src/xdrawtri.asm
new file mode 100644
index 0000000..a66fc3a
--- /dev/null
+++ b/glide3x/h3/glide3/src/xdrawtri.asm
@@ -0,0 +1,67 @@
+;; THIS SOFTWARE IS SUBJECT TO COPYRIGHT PROTECTION AND IS OFFERED ONLY
+;; PURSUANT TO THE 3DFX GLIDE GENERAL PUBLIC LICENSE. THERE IS NO RIGHT
+;; TO USE THE GLIDE TRADEMARK WITHOUT PRIOR WRITTEN PERMISSION OF 3DFX
+;; INTERACTIVE, INC. A COPY OF THIS LICENSE MAY BE OBTAINED FROM THE
+;; DISTRIBUTOR OR BY CONTACTING 3DFX INTERACTIVE INC(info@3dfx.com).
+;; THIS PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
+;; EXPRESSED OR IMPLIED. SEE THE 3DFX GLIDE GENERAL PUBLIC LICENSE FOR A
+;; FULL TEXT OF THE NON-WARRANTY PROVISIONS.
+;;
+;; USE, DUPLICATION OR DISCLOSURE BY THE GOVERNMENT IS SUBJECT TO
+;; RESTRICTIONS AS SET FORTH IN SUBDIVISION (C)(1)(II) OF THE RIGHTS IN
+;; TECHNICAL DATA AND COMPUTER SOFTWARE CLAUSE AT DFARS 252.227-7013,
+;; AND/OR IN SIMILAR OR SUCCESSOR CLAUSES IN THE FAR, DOD OR NASA FAR
+;; SUPPLEMENT. UNPUBLISHED RIGHTS RESERVED UNDER THE COPYRIGHT LAWS OF
+;; THE UNITED STATES.
+;;
+;; COPYRIGHT 3DFX INTERACTIVE, INC. 1999, ALL RIGHTS RESERVED
+
+;; Adapted from gdraw.c:grDrawTriangle() for nasm
+
+%include "xos.inc"
+
+%if XOS == XOS_WIN32
+%else
+%error This source is only meant for x86/Windows
+%endif
+
+%include "fxgasm.h"
+
+; tls constants (from fxglide.h)
+%define W95_TEB_PTR        0x18
+%define W95_TEB_TLS_OFFSET 0x88
+%define WNT_TEB_PTR        0x18
+%define WNT_TEB_TLS_OFFSET 0xE10
+
+extrn   _GlideRoot
+
+segment SEG_TEXT
+
+            align 4
+proc grDrawTriangle, 12
+
+	mov		eax, dword [fs:WNT_TEB_PTR]
+	add		eax, dword [_GlideRoot+tlsOffset]
+	mov		edx, dword [eax]
+	test		edx, edx
+	je		L0
+	mov		eax, dword [edx+lostContext]
+	test		eax, eax
+	je		L0
+	mov		eax, dword [eax]
+	test		eax, 1
+	jnz		L0
+	mov		eax, dword [edx+kTriProcOffset]
+	jmp		eax
+L0:	; lostContext
+; MSVC doesn't emit a RET here in gdraw.obj, which seems wrong.
+	ret
+
+endp
+
+%ifdef __MINGW32__
+; GNU LD fails with '_' prefix
+export  grDrawTriangle@12
+%else
+export _grDrawTriangle@12
+%endif