First checkpoint for picking apart and reworking transformations

main.c

@@ -357,23 +357,45 @@ void drawModel(ps1mdl_t *model, ps1skin_t *skin, int frameCounter)
 	short u0, u1, u2, uoffs, voffs;
 	int p;
 
+	int frameNum = frameCounter % model->header->frameCount;
+	int vertOffs = frameNum * model->header->vertexCount;
+	short halfSkinWidth = model->header->skinWidth >> 1;
+
+	int *scale = model->header->scale;
+	int *translate = model->header->translate;
+
+	// Expected order of things:
+	// - Initial scale matrix to correct aspect ratio
+	// - Coordinate system swizzle (scale) (can probably be combined with the above)
+	// - Camera inverse translation
+	// - Camera inverse rotation (apply on top of camera translation)
+	// - Multiply light matrix (lights will be in Quake coordinate system)
+	// - Push matrix
+	// - Entity local rotation
+	// - Entity local translation
+	// - Model internal scale
+	// - Model internal translate
+	// - Render
+	// - Pop matrix
+
 	MATRIX mtx, lmtx;
 	RotMatrix(&model->rotation, &mtx);
 	ScaleMatrixL(&mtx, &cam_scale);		// Aspect ratio correction
 	TransMatrix(&mtx, &model->position);
 	MulMatrix0(&light_mtx, &mtx, &lmtx);
 
+	// Model internal scale and translate, to transform vertices from [0..255] range to a larger dynamic range with appropriate world-relative size
+	// Swizzle the coordinates because Quake Z is up
+	// Finding the appropriate scale range here is tricky. Without the << 2 scale the vertex coordinates become so small that you lose depth precision.
+	MATRIX local = { .m = { ONE << 2, 0, 0, 0, 0, -ONE << 2, 0, ONE << 2, 0 }, .t = { 0 } };
+	ScaleMatrixL(&local, (VECTOR*)scale);
+	TransMatrix(&local, (VECTOR*)translate);
+	MulMatrix(&mtx, &local);
+
 	gte_SetRotMatrix(&mtx);
 	gte_SetTransMatrix(&mtx);
 	gte_SetLightMatrix(&lmtx);
 
-	int frameNum = frameCounter % model->header->frameCount;
-	int vertOffs = frameNum * model->header->vertexCount;
-	short halfSkinWidth = model->header->skinWidth >> 1;
-
-	int *scale = model->header->scale;
-	int *translate = model->header->translate;
-
 	for (int triIdx = 0; triIdx < model->header->triangleCount; ++triIdx)
 	{
 		ps1mdl_triangle_t *tri = &model->triangles[triIdx];
@@ -382,12 +404,9 @@ void drawModel(ps1mdl_t *model, ps1skin_t *skin, int frameCounter)
 		ps1mdl_vertex_t *v1 = &model->vertices[tri->vertexIndex[1] + vertOffs];
 		ps1mdl_vertex_t *v2 = &model->vertices[tri->vertexIndex[2] + vertOffs];
 
-		// Swizzle the coordinates because Quake Z is up
-		// TODO: scale and translate should be done by the GTE instead of through software here
-		// Finding the appropriate scale range here is tricky. Normalize with >> 12 as usual and the coordinates become so small that you lose depth precision.
-		SVECTOR pos0 = { (scale[0] * v0->position[0] + translate[0]) >> 10, (scale[2] * -v0->position[2] + translate[2]) >> 10, (scale[1] * v0->position[1] + translate[1]) >> 10, 0 };
-		SVECTOR pos1 = { (scale[0] * v1->position[0] + translate[0]) >> 10, (scale[2] * -v1->position[2] + translate[2]) >> 10, (scale[1] * v1->position[1] + translate[1]) >> 10, 0 };
-		SVECTOR pos2 = { (scale[0] * v2->position[0] + translate[0]) >> 10, (scale[2] * -v2->position[2] + translate[2]) >> 10, (scale[1] * v2->position[1] + translate[1]) >> 10, 0 };
+		SVECTOR pos0 = { v0->position[0], v0->position[1], v0->position[2], 0 };
+		SVECTOR pos1 = { v1->position[0], v1->position[1], v1->position[2], 0 };
+		SVECTOR pos2 = { v2->position[0], v2->position[1], v2->position[2], 0 };
 
 		gte_ldv3(&pos0, &pos1, &pos2);
 		gte_rtpt();	// Rotation, Translation and Perspective triplet (all three vertices at once)
@@ -439,6 +458,7 @@ void drawModel(ps1mdl_t *model, ps1skin_t *skin, int frameCounter)
 		outPos.vz = p;
 
 		// Calculate vertex color based on normal
+		// TODO: we could probably speed this up by precalculating the lighting for each normal, if we need to draw more than 162 vertices
 		gte_ldrgb(&poly->r0);
 		gte_ldv3(anorms[v0->normalIndex], anorms[v1->normalIndex], anorms[v2->normalIndex]);
 		gte_nct();
@@ -466,7 +486,7 @@ void drawStuff(int counter)
 	FntFlush(-1);
 
 	gte_SetBackColor(48, 48, 48);	// Ambient light color
-	gte_SetColorMatrix(&color_mtx);	// Light color and direction
+	gte_SetColorMatrix(&color_mtx);	// Light color (up to three different lights)
 
 	drawModel(&playerModel, &playerSkin, counter >> 2);
 	drawModel(&shamblerModel, &shamblerSkin, counter >> 2);