/*  V2MemTest - A CLI Tool to test & fix Voodoo² TMU System
*   Copyright (C) 2026  ChaCha
*
*   This program is free software: you can redistribute it and/or modify
*   it 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.
*
*   This program is distributed in the hope that it will be useful,
*   but WITHOUT ANY WARRANTY; without even the implied warranty of
*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*   GNU General Public License for more details.
*
*   You should have received a copy of the GNU General Public License
*   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

#include "cvg.h"
#include "glide.h"
#include "sst1init.h"

#include "Draw.h"

#define XY_ONE (1 << SST_XY_FRACBITS)
#define ST_ONE (1 << SST_ST_FRACBITS)
#define W_ONE  (1 << SST_W_FRACBITS)

typedef struct _def_sPoint
{
	int16_t x;
	int16_t y;
}def_sPoint;

typedef struct _def_sTriangle
{
	def_sPoint vA;
	def_sPoint vB;
	def_sPoint vC;
	int32_t	s;
	int32_t	t;
	int32_t	w;
	int32_t	dsdx;
	int32_t	dtdx;
	int32_t	dwdx;
	int32_t	dsdy;
	int32_t	dtdy;
	int32_t	dwdy;
}def_sTriangle;

static inline uint32_t v2_triangle_cmd_from_abc(const def_sPoint A, 
												const def_sPoint B, 
												const def_sPoint C)
{
	const int32_t abx = (int32_t)B.x - (int32_t)A.x;
	const int32_t aby = (int32_t)B.y - (int32_t)A.y;
	const int32_t acx = (int32_t)C.x - (int32_t)A.x;
	const int32_t acy = (int32_t)C.y - (int32_t)A.y;
	const int64_t  s = (int64_t )abx * (int64_t )acy - (int64_t )aby * (int64_t )acx;
	return (s < 0) ? 0x80000000u : 0u;
}
static void inline drawTriangle(const SstRegs * const sst, const def_sTriangle * const sTri)
{
	ISET(sst->vA.x,	sTri->vA.x*XY_ONE);	ISET(sst->vA.y,	sTri->vA.y*XY_ONE);
	ISET(sst->vB.x,	sTri->vB.x*XY_ONE);	ISET(sst->vB.y,	sTri->vB.y*XY_ONE);
	ISET(sst->vC.x,	sTri->vC.x*XY_ONE);	ISET(sst->vC.y,	sTri->vC.y*XY_ONE);
	ISET(sst->s,		sTri->s*ST_ONE);
	ISET(sst->t,		sTri->t*ST_ONE);
	ISET(sst->w,		sTri->w*W_ONE);
	ISET(sst->dsdx,		sTri->dsdx*ST_ONE);
	ISET(sst->dtdx,		sTri->dtdx*ST_ONE);
	ISET(sst->dwdx,		sTri->dwdx*W_ONE);
	ISET(sst->dsdy,		sTri->dsdy*ST_ONE);
	ISET(sst->dtdy,		sTri->dtdy*ST_ONE);
	ISET(sst->dwdy,		sTri->dwdy*W_ONE);
	ISET(sst->triangleCMD,v2_triangle_cmd_from_abc(sTri->vA, sTri->vB, sTri->vC));
}

void
drawSquare(	const SstRegs * const sst, 
			const int16_t x, 
			const int16_t y, 
			const int16_t tSize)
{
	const def_sTriangle tri1 = {
		.vA = {.x= (x+0),		.y = (y+0)},
		.vB = {.x= (x+tSize),	.y = (y+0)},
		.vC = {.x= (x+0),		.y = (y+tSize)},
		.s = 0,
		.t = 0,
		.w = 1,
		.dsdx = 1, .dtdx = 0,
		.dwdx = 0
		.dsdy = 0, .dtdy = 1,
		.dwdy = 0};
	drawTriangle(sst, &tri1);
	
	const def_sTriangle tri2 = {
		.vA = {.x= (x+0),		.y = (y+tSize)},
		.vB = {.x= (x+tSize),	.y = (y+0)},
		.vC = {.x= (x+tSize),	.y = (y+tSize)},
		.s = 0,
		.t = tSize,
		.w = 1,
		.dsdx = 1, .dtdx = 0,
		.dwdx = 0
		.dsdy = 0, .dtdy = 1,
		.dwdy = 0 };
	drawTriangle(sst, &tri2);
}