Add some experimental draw triangle code

src/r_draw_rgba.cpp

@@ -1256,6 +1256,255 @@ void ApplySpecialColormapRGBACommand::Execute(DrawerThread *thread)
 
 /////////////////////////////////////////////////////////////////////////////
 
+struct TriVertex
+{
+	enum { NumVarying = 3 };
+	float x, y, z, w;
+	float varying[NumVarying];
+};
+
+float gradx(float x0, float y0, float x1, float y1, float x2, float y2, float c0, float c1, float c2)
+{
+	float top = (c1 - c2) * (y0 - y2) - (c0 - c2) * (y1 - y2);
+	float bottom = (x1 - x2) * (y0 - y2) - (x0 - x2) * (y1 - y2);
+	return top / bottom;
+}
+
+float grady(float x0, float y0, float x1, float y1, float x2, float y2, float c0, float c1, float c2)
+{
+	float top = (c1 - c2) * (x0 - x2) - (c0 - c2) * (x1 - x2);
+	float bottom = -((x1 - x2) * (y0 - y2) - (x0 - x2) * (y1 - y2));
+	return top / bottom;
+}
+
+void triangle(uint32_t *dest, int pitch, const TriVertex &v1, const TriVertex &v2, const TriVertex &v3)
+{
+	// 28.4 fixed-point coordinates
+	const int Y1 = (int)round(16.0f * v1.y);
+	const int Y2 = (int)round(16.0f * v2.y);
+	const int Y3 = (int)round(16.0f * v3.y);
+
+	const int X1 = (int)round(16.0f * v1.x);
+	const int X2 = (int)round(16.0f * v2.x);
+	const int X3 = (int)round(16.0f * v3.x);
+
+	// Deltas
+	const int DX12 = X1 - X2;
+	const int DX23 = X2 - X3;
+	const int DX31 = X3 - X1;
+
+	const int DY12 = Y1 - Y2;
+	const int DY23 = Y2 - Y3;
+	const int DY31 = Y3 - Y1;
+
+	// Fixed-point deltas
+	const int FDX12 = DX12 << 4;
+	const int FDX23 = DX23 << 4;
+	const int FDX31 = DX31 << 4;
+
+	const int FDY12 = DY12 << 4;
+	const int FDY23 = DY23 << 4;
+	const int FDY31 = DY31 << 4;
+
+	// Bounding rectangle
+	int minx = (MIN(MIN(X1, X2), X3) + 0xF) >> 4;
+	int maxx = (MAX(MAX(X1, X2), X3) + 0xF) >> 4;
+	int miny = (MIN(MIN(Y1, Y2), Y3) + 0xF) >> 4;
+	int maxy = (MAX(MAX(Y1, Y2), Y3) + 0xF) >> 4;
+
+	// Block size, standard 8x8 (must be power of two)
+	const int q = 8;
+
+	// Start in corner of 8x8 block
+	minx &= ~(q - 1);
+	miny &= ~(q - 1);
+
+	dest += miny * pitch;
+
+	// Half-edge constants
+	int C1 = DY12 * X1 - DX12 * Y1;
+	int C2 = DY23 * X2 - DX23 * Y2;
+	int C3 = DY31 * X3 - DX31 * Y3;
+
+	// Correct for fill convention
+	if (DY12 < 0 || (DY12 == 0 && DX12 > 0)) C1++;
+	if (DY23 < 0 || (DY23 == 0 && DX23 > 0)) C2++;
+	if (DY31 < 0 || (DY31 == 0 && DX31 > 0)) C3++;
+
+	// Gradients
+	float gradWX = gradx(v1.x, v1.y, v2.x, v2.y, v3.x, v3.y, v1.w, v2.w, v3.w);
+	float gradWY = grady(v1.x, v1.y, v2.x, v2.y, v3.x, v3.y, v1.w, v2.w, v3.w);
+	float startW = v1.w + gradWX * (minx - v1.x) + gradWY * (miny - v1.y);
+	float gradVaryingX[TriVertex::NumVarying], gradVaryingY[TriVertex::NumVarying], startVarying[TriVertex::NumVarying];
+	for (int i = 0; i < TriVertex::NumVarying; i++)
+	{
+		gradVaryingX[i] = gradx(v1.x, v1.y, v2.x, v2.y, v3.x, v3.y, v1.varying[i] * v1.w, v2.varying[i] * v2.w, v3.varying[i] * v3.w);
+		gradVaryingY[i] = grady(v1.x, v1.y, v2.x, v2.y, v3.x, v3.y, v1.varying[i] * v1.w, v2.varying[i] * v2.w, v3.varying[i] * v3.w);
+		startVarying[i] = v1.varying[i] * v1.w + gradVaryingX[i] * (minx - v1.x) + gradVaryingY[i] * (miny - v1.y);
+	}
+
+	// Loop through blocks
+	for (int y = miny; y < maxy; y += q)
+	{
+		for (int x = minx; x < maxx; x += q)
+		{
+			// Corners of block
+			int x0 = x << 4;
+			int x1 = (x + q - 1) << 4;
+			int y0 = y << 4;
+			int y1 = (y + q - 1) << 4;
+
+			// Evaluate half-space functions
+			bool a00 = C1 + DX12 * y0 - DY12 * x0 > 0;
+			bool a10 = C1 + DX12 * y0 - DY12 * x1 > 0;
+			bool a01 = C1 + DX12 * y1 - DY12 * x0 > 0;
+			bool a11 = C1 + DX12 * y1 - DY12 * x1 > 0;
+			int a = (a00 << 0) | (a10 << 1) | (a01 << 2) | (a11 << 3);
+
+			bool b00 = C2 + DX23 * y0 - DY23 * x0 > 0;
+			bool b10 = C2 + DX23 * y0 - DY23 * x1 > 0;
+			bool b01 = C2 + DX23 * y1 - DY23 * x0 > 0;
+			bool b11 = C2 + DX23 * y1 - DY23 * x1 > 0;
+			int b = (b00 << 0) | (b10 << 1) | (b01 << 2) | (b11 << 3);
+
+			bool c00 = C3 + DX31 * y0 - DY31 * x0 > 0;
+			bool c10 = C3 + DX31 * y0 - DY31 * x1 > 0;
+			bool c01 = C3 + DX31 * y1 - DY31 * x0 > 0;
+			bool c11 = C3 + DX31 * y1 - DY31 * x1 > 0;
+			int c = (c00 << 0) | (c10 << 1) | (c01 << 2) | (c11 << 3);
+
+			// Skip block when outside an edge
+			if (a == 0x0 || b == 0x0 || c == 0x0) continue;
+
+			// Calculate varying variables for affine block
+			float offx0 = (x - minx) + 0.5f;
+			float offy0 = (y - miny) + 0.5f;
+			float offx1 = offx0 + q;
+			float offy1 = offy0 + q;
+			float rcpWTL = 1.0f / (startW + offx0 * gradWX + offy0 * gradWY);
+			float rcpWTR = 1.0f / (startW + offx1 * gradWX + offy0 * gradWY);
+			float rcpWBL = 1.0f / (startW + offx0 * gradWX + offy1 * gradWY);
+			float rcpWBR = 1.0f / (startW + offx1 * gradWX + offy1 * gradWY);
+			float varyingTL[TriVertex::NumVarying];
+			float varyingTR[TriVertex::NumVarying];
+			float varyingBL[TriVertex::NumVarying];
+			float varyingBR[TriVertex::NumVarying];
+			for (int i = 0; i < TriVertex::NumVarying; i++)
+			{
+				varyingTL[i] = (startVarying[i] + offx0 * gradVaryingX[i] + offy0 * gradVaryingY[i]) * rcpWTL;
+				varyingTR[i] = (startVarying[i] + offx1 * gradVaryingX[i] + offy0 * gradVaryingY[i]) * rcpWTR;
+				varyingBL[i] = ((startVarying[i] + offx0 * gradVaryingX[i] + offy1 * gradVaryingY[i]) * rcpWBL - varyingTL[i]) * (1.0f / q);
+				varyingBR[i] = ((startVarying[i] + offx1 * gradVaryingX[i] + offy1 * gradVaryingY[i]) * rcpWBR - varyingTR[i]) * (1.0f / q);
+			}
+
+			uint32_t *buffer = dest;
+
+			// Accept whole block when totally covered
+			if (a == 0xF && b == 0xF && c == 0xF)
+			{
+				for (int iy = 0; iy < q; iy++)
+				{
+					float varying[TriVertex::NumVarying], varyingStep[TriVertex::NumVarying];
+					for (int i = 0; i < TriVertex::NumVarying; i++)
+					{
+						varying[i] = varyingTL[i] + varyingBL[i] * iy;
+						varyingStep[i] = (varyingTR[i] + varyingBR[i] * iy - varying[i]) * (1.0f / q);
+					}
+
+					for (int ix = x; ix < x + q; ix++)
+					{
+						uint32_t red = (uint32_t)clamp(varying[0] * 255.0f + 0.5f, 0.0f, 255.0f);
+						uint32_t green = (uint32_t)clamp(varying[1] * 255.0f + 0.5f, 0.0f, 255.0f);
+						uint32_t blue = (uint32_t)clamp(varying[2] * 255.0f + 0.5f, 0.0f, 255.0f);
+
+						buffer[ix] = 0xff000000 | (red << 16) | (green << 8) | blue;
+
+						for (int i = 0; i < TriVertex::NumVarying; i++)
+							varying[i] += varyingStep[i];
+					}
+
+					buffer += pitch;
+				}
+			}
+			else // Partially covered block
+			{
+				int CY1 = C1 + DX12 * y0 - DY12 * x0;
+				int CY2 = C2 + DX23 * y0 - DY23 * x0;
+				int CY3 = C3 + DX31 * y0 - DY31 * x0;
+
+				for (int iy = 0; iy < q; iy++)
+				{
+					int CX1 = CY1;
+					int CX2 = CY2;
+					int CX3 = CY3;
+
+					float varying[TriVertex::NumVarying], varyingStep[TriVertex::NumVarying];
+					for (int i = 0; i < TriVertex::NumVarying; i++)
+					{
+						varying[i] = varyingTL[i] + varyingBL[i] * iy;
+						varyingStep[i] = (varyingTR[i] + varyingBR[i] * iy - varying[i]) * (1.0f / q);
+					}
+
+					for (int ix = x; ix < x + q; ix++)
+					{
+						if (CX1 > 0 && CX2 > 0 && CX3 > 0)
+						{
+							uint32_t red = (uint32_t)clamp(varying[0] * 255.0f + 0.5f, 0.0f, 255.0f);
+							uint32_t green = (uint32_t)clamp(varying[1] * 255.0f + 0.5f, 0.0f, 255.0f);
+							uint32_t blue = (uint32_t)clamp(varying[2] * 255.0f + 0.5f, 0.0f, 255.0f);
+
+							buffer[ix] = 0xff000000 | (red << 16) | (green << 8) | blue;
+						}
+
+						for (int i = 0; i < TriVertex::NumVarying; i++)
+							varying[i] += varyingStep[i];
+
+						CX1 -= FDY12;
+						CX2 -= FDY23;
+						CX3 -= FDY31;
+					}
+
+					CY1 += FDX12;
+					CY2 += FDX23;
+					CY3 += FDX31;
+
+					buffer += pitch;
+				}
+			}
+		}
+
+		dest += q * pitch;
+	}
+}
+
+void R_DrawTriangle()
+{
+	TriVertex trivert[6];
+
+	trivert[0].x = 100;
+	trivert[0].y = 350;
+	trivert[0].w = 1.0f;
+	trivert[0].varying[0] = 0.0f;
+	trivert[0].varying[1] = 1.0f;
+	trivert[0].varying[2] = 0.0f;
+	trivert[1].x = 400;
+	trivert[1].y = 500;
+	trivert[1].w = 1.0f;
+	trivert[1].varying[0] = 1.0f;
+	trivert[1].varying[1] = 0.0f;
+	trivert[1].varying[2] = 0.0f;
+	trivert[2].x = 200;
+	trivert[2].y = 200;
+	trivert[2].w = 1.0f;
+	trivert[2].varying[0] = 0.0f;
+	trivert[2].varying[1] = 0.0f;
+	trivert[2].varying[2] = 1.0f;
+
+	triangle((uint32_t*)dc_destorg, dc_pitch, trivert[0], trivert[1], trivert[2]);
+}
+
+/////////////////////////////////////////////////////////////////////////////
+
 void R_DrawSingleSkyCol1(uint32_t solid_top, uint32_t solid_bottom)
 {
 	DrawerCommandQueue::QueueCommand<DrawSingleSky1LLVMCommand>(solid_top, solid_bottom);

src/r_swrenderer.cpp

@@ -47,10 +47,13 @@
 
 EXTERN_CVAR(Bool, r_shadercolormaps)
 
+CVAR(Bool, r_drawtriangle, false, 0)
+
 void R_SWRSetWindow(int windowSize, int fullWidth, int fullHeight, int stHeight, float trueratio);
 void R_SetupColormap(player_t *);
 void R_SetupFreelook();
 void R_InitRenderer();
+void R_DrawTriangle();
 
 FSoftwareRenderer::FSoftwareRenderer()
 {
@@ -192,6 +195,8 @@ void FSoftwareRenderer::RenderView(player_t *player)
 	}
 
 	R_EndDrawerCommands();
+	if (r_swtruecolor && r_drawtriangle)
+		R_DrawTriangle();
 }
 
 //==========================================================================