[mtl canvas] Fix artifacts on tiger that was due to epsilon comparison for cubics equation in draw kernel. Removed that (now do <= 0), but then we need to weed out false negatives for solid triangles. So we compute if the triangle is solid in the triangle kernel and store it in the mg_triangle_data struct for now.

examples/tiger/main.c

@@ -65,7 +65,7 @@ int main()
 
 	//NOTE: create surface
 	mg_surface surface = mg_surface_create_for_window(window, MG_BACKEND_DEFAULT);
-	mg_surface_swap_interval(surface, 0);
+	mg_surface_swap_interval(surface, 1);
 
 	//TODO: create canvas
 	mg_canvas canvas = mg_canvas_create(surface);
@@ -85,7 +85,7 @@ int main()
 	bool tracked = false;
 	vec2 trackPoint = {0};
 	f32 zoom = 1;
-	f32 startX = 0, startY = 0;
+	f32 startX = 300, startY = 200;
 
 	f64 frameTime = 0;
 
@@ -112,8 +112,8 @@ int main()
 						{
 							tracked = true;
 							vec2 mousePos = mp_mouse_position();
-							trackPoint.x = mousePos.x/zoom - startX;
+							trackPoint.x = (mousePos.x - startX)/zoom;
-							trackPoint.y = mousePos.y/zoom - startY;
+							trackPoint.y = (mousePos.y - startY)/zoom;
 						}
 						else
 						{
@@ -125,14 +125,14 @@ int main()
 				case MP_EVENT_MOUSE_WHEEL:
 				{
 					vec2 mousePos = mp_mouse_position();
-					f32 trackX = mousePos.x/zoom - startX;
+					f32 pinX = (mousePos.x - startX)/zoom;
-					f32 trackY = mousePos.y/zoom - startY;
+					f32 pinY = (mousePos.y - startY)/zoom;
 
 					zoom *= 1 + event.move.deltaY * 0.01;
-					zoom = Clamp(zoom, 0.2, 10);
+					zoom = Clamp(zoom, 0.5, 5);
 
-					startX = mousePos.x/zoom - trackX;
+					startX = mousePos.x - pinX*zoom;
-					startY = mousePos.y/zoom - trackY;
+					startY = mousePos.y - pinY*zoom;
 				} break;
 
 				default:
@@ -143,8 +143,8 @@ int main()
 		if(tracked)
 		{
 			vec2 mousePos = mp_mouse_position();
-			startX = mousePos.x/zoom - trackPoint.x;
+			startX = mousePos.x - trackPoint.x*zoom;
-			startY = mousePos.y/zoom - trackPoint.y;
+			startY = mousePos.y - trackPoint.y*zoom;
 		}
 
 		mg_surface_prepare(surface);
@@ -152,8 +152,8 @@ int main()
 		mg_set_color_rgba(1, 0, 1, 1);
 		mg_clear();
 
-		mg_matrix_push((mg_mat2x3){zoom, 0, 300+startX*zoom,
+		mg_matrix_push((mg_mat2x3){zoom, 0, startX,
-		                           0, zoom, 200+startY*zoom});
+		                           0, zoom, startY});
 
 		draw_tiger();
 

examples/tiger/svg2mg.py

@@ -208,10 +208,13 @@ for g in tree.iter('{http://www.w3.org/2000/svg}g'):
 			print("\tmg_set_color_rgba(" + f2s(r) + ", " + f2s(g) + ", " + f2s(b) + ", 1);")
 			print("\tmg_fill();")
 
-		if stroke_width != None:
-			print("\tmg_set_width(" + stroke_width + ");");
-
 		if stroke != None and stroke != "none":
+
+			if stroke_width != None:
+				print("\tmg_set_width(" + stroke_width + ");");
+			else:
+				print("\tmg_set_width(1);");
+
 			(r, g, b) = parse_color(stroke)
 			if fill != None:
 				ctx.reset()

examples/tiger/tiger.c

@@ -284,6 +284,7 @@ void draw_tiger()
 	mg_close_path();
 	mg_set_color_rgba(1.000, 1.000, 1.000, 1);
 	mg_fill();
+	mg_set_width(1);
 	mg_move_to(-129.830, 103.060);
 	mg_cubic_to(-129.330, 109.110, -128.340, 115.680, -126.600, 118.800);
 	mg_cubic_to(-126.600, 118.800, -130.200, 131.200, -121.400, 144.400);
@@ -422,6 +423,7 @@ void draw_tiger()
 	mg_close_path();
 	mg_set_color_rgba(0.800, 0.447, 0.149, 1);
 	mg_fill();
+	mg_set_width(1);
 	mg_move_to(299.720, 80.245);
 	mg_cubic_to(300.340, 80.426, 302.550, 81.550, 303.800, 83.200);
 	mg_cubic_to(303.800, 83.200, 310.600, 94.000, 305.400, 75.600);
@@ -909,6 +911,7 @@ void draw_tiger()
 	mg_close_path();
 	mg_set_color_rgba(1.000, 0.447, 0.498, 1);
 	mg_fill();
+	mg_set_width(1);
 	mg_move_to(-9.800, 174.400);
 	mg_cubic_to(-9.800, 174.400, -12.600, 196.800, -9.400, 205.200);
 	mg_cubic_to(-6.200, 213.600, -7.000, 215.600, -7.800, 219.600);
@@ -3879,21 +3882,25 @@ void draw_tiger()
 
 	mg_move_to(-89.250, 169.000);
 	mg_move_to(-67.250, 173.750);
+	mg_set_width(1);
 	mg_set_color_rgba(0.000, 0.000, 0.000, 1);
 	mg_stroke();
 
 	mg_move_to(-39.000, 331.000);
 	mg_cubic_to(-39.000, 331.000, -39.500, 327.500, -48.500, 338.000);
+	mg_set_width(1);
 	mg_set_color_rgba(0.000, 0.000, 0.000, 1);
 	mg_stroke();
 
 	mg_move_to(-33.500, 336.000);
 	mg_cubic_to(-33.500, 336.000, -31.500, 329.500, -38.000, 334.000);
+	mg_set_width(1);
 	mg_set_color_rgba(0.000, 0.000, 0.000, 1);
 	mg_stroke();
 
 	mg_move_to(20.500, 344.500);
 	mg_cubic_to(20.500, 344.500, 22.000, 333.500, 10.500, 346.500);
+	mg_set_width(1);
 	mg_set_color_rgba(0.000, 0.000, 0.000, 1);
 	mg_stroke();
 

src/mtl_shader.h

@@ -13,7 +13,7 @@
 
 #define RENDERER_TILE_SIZE 16
 #define RENDERER_MAX_TILES 65536
-#define RENDERER_TILE_BUFFER_COUNT 4*(1<<10)
+#define RENDERER_TILE_BUFFER_COUNT 8*(1<<10)
 
 #define RENDERER_DEBUG_TILE_VISITED 0xf00d
 #define RENDERER_DEBUG_TILE_BUFFER_OVERFLOW 0xdead
@@ -38,6 +38,7 @@ typedef struct mg_triangle_data
 	matrix_float3x3 uvTransform;
 	vector_float4 color;
 
+	bool full;
 	vector_float4 cubic0;
 	vector_float4 cubic1;
 	vector_float4 cubic2;

src/mtl_shader.metal

@@ -158,6 +158,12 @@ kernel void TriangleKernel(constant mg_vertex* vertexBuffer [[buffer(0)]],
 	triangleArray[gid].bias1 = is_top_left(p2, p0) ? -(1-cw)/2 : -(1+cw)/2;
 	triangleArray[gid].bias2 = is_top_left(p0, p1) ? -(1-cw)/2 : -(1+cw)/2;
 
+	bool triangleFull = all(  triangleArray[gid].cubic0 == float4(1, 1, 1, 1)
+	                       && triangleArray[gid].cubic1 == float4(1, 1, 1, 1)
+	                       && triangleArray[gid].cubic2 == float4(1, 1, 1, 1));
+
+	triangleArray[gid].full = triangleFull;
+
 	int4 coarseBox = int4(fbox)/RENDERER_TILE_SIZE;
 
 	//NOTE: bucket triangle into tiles
@@ -172,10 +178,6 @@ kernel void TriangleKernel(constant mg_vertex* vertexBuffer [[buffer(0)]],
 	//NOTE(martin): it's important to do the computation with signed int, so that we can have negative xMax/yMax
 	//              otherwise all triangles on the left or below the x/y axis are attributed to tiles on row/column 0.
 
-	bool triangleFull = all(  triangleArray[gid].cubic0 == float4(1, 1, 1, 1)
-	                       && triangleArray[gid].cubic1 == float4(1, 1, 1, 1)
-	                       && triangleArray[gid].cubic2 == float4(1, 1, 1, 1));
-
 	int2 edges[3][2] = {{ip0, ip1}, {ip1, ip2}, {ip2, ip0}};
 
 	for(int y = yMin; y <= yMax; y++)
@@ -450,6 +452,8 @@ kernel void RenderKernel(const device uint* tileCounters [[buffer(0)]],
 			float4 cubic1 = triangle->cubic1;
 			float4 cubic2 = triangle->cubic2;
 
+			bool fullTriangle = triangle->full;
+
 			int shapeIndex = triangle->shapeIndex;
 			float4 color = triangle->color;
 			color.rgb *= color.a;
@@ -478,8 +482,8 @@ kernel void RenderKernel(const device uint* tileCounters [[buffer(0)]],
 				{
 					float4 cubic = (cubic0*w0 + cubic1*w1 + cubic2*w2)/(w0+w1+w2);
 
-					float eps = 0.0001;
+					if( fullTriangle
-					if(cubic.w*(cubic.x*cubic.x*cubic.x - cubic.y*cubic.z) <= eps)
+					  ||(cubic.w*(cubic.x*cubic.x*cubic.x - cubic.y*cubic.z) <= 0))
 					{
 						if(shapeIndex == currentShapeIndex[sampleIndex])
 						{