[mtl canvas] prevent tiles entirely covered by textured shapes to be treated as solid (as the texture could be non-uniformly transparent)

src/graphics.c

@@ -816,6 +816,7 @@ u32 mg_next_shape(mg_canvas_data* canvas, mg_attributes* attributes)
 	canvas->nextShapeIndex++;
 
 	*(mg_color*)(((char*)layout->colorBuffer) + index*layout->colorStride) = attributes->color;
+	*(bool*)(((char*)layout->texturedBuffer) + index*layout->texturedStride) = !mg_image_is_nil(attributes->image);
 
 	return(index);
 }

src/graphics_internal.h

@@ -90,6 +90,9 @@ typedef struct mg_vertex_layout
 	char* colorBuffer;
 	u32 colorStride;
 
+	char* texturedBuffer;
+	u32 texturedStride;
+
 	char* shapeIndexBuffer;
 	u32 shapeIndexStride;
 

src/mtl_canvas.m

@@ -104,6 +104,10 @@ void mg_mtl_canvas_update_vertex_layout(mg_mtl_canvas_backend* backend)
 
 	        .colorBuffer = shapeBase + offsetof(mg_shape, color),
 	        .colorStride = sizeof(mg_shape),
+
+	        .texturedBuffer = shapeBase + offsetof(mg_shape, textured),
+	        .texturedStride = sizeof(mg_shape),
+
 	        .clipBuffer = shapeBase + offsetof(mg_shape, clip),
 	        .clipStride = sizeof(mg_shape),
 	        .uvTransformBuffer = shapeBase + offsetof(mg_shape, uvTransform),

src/mtl_shader.h

@@ -30,7 +30,7 @@ typedef struct mg_shape
 	vector_float4 color;
 	vector_float4 clip;
 	float uvTransform[6];
-
+	bool textured;
 } mg_shape;
 
 typedef struct mg_triangle_data
@@ -64,17 +64,15 @@ typedef struct mg_triangle_data
 using namespace metal;
 #endif
 
+#define MG_TILE_CMD_MASK (1<<31)
+
 typedef enum mg_tile_cmd_kind
 {
-	mg_cmd_triangle,
+	mg_cmd_triangle = 0,
-	mg_cmd_color
+	mg_cmd_color = 1<<31,
 } mg_tile_cmd_kind;
 
-typedef struct mg_tile_cmd
+typedef int mg_tile_cmd;
-{
-	mg_tile_cmd_kind kind;
-	int triangleIndex;
-} mg_tile_cmd;
 
 typedef struct mg_tile_elt
 {
@@ -89,6 +87,7 @@ typedef struct mg_tile
 	atomic_int eltCount;
 	atomic_int partial;
 	atomic_int flipCount;
+	bool textured;
 
 } mg_tile;
 

src/mtl_shader.metal

@@ -87,6 +87,7 @@ kernel void ShapeSetup(constant mg_shape* shapeBuffer [[buffer(0)]],
 	for(int i=0; i<tileCount; i++)
 	{
 		tiles[i].color = shapeBuffer[gid].color;
+		tiles[i].textured = shapeBuffer[gid].textured;
 		atomic_store_explicit(&tiles[i].firstElt, -1, memory_order_relaxed);
 		atomic_store_explicit(&tiles[i].eltCount, 0, memory_order_relaxed);
 		atomic_store_explicit(&tiles[i].partial, 0, memory_order_relaxed);
@@ -300,15 +301,14 @@ kernel void GatherKernel(const device mg_shape_queue* shapeQueueBuffer [[buffer(
 			{
 				if(atomic_load_explicit(&tile->flipCount, memory_order_relaxed) & 0x01)
 				{
-					if(tile->color.a == 1)
+					if(tile->color.a == 1 && !tile->textured)
 					{
-						//NOTE: tile is full covered by a solid color, reset counter
+						//NOTE: tile is full covered by a solid color, reset counter and push a color command
 						int firstEltIndex = *(device int*)&tile->firstElt;
 						const device mg_tile_elt* elt = &eltBuffer[firstEltIndex];
 
 						count = 0;
-						tileArray[count].kind = mg_cmd_color;
+						tileArray[count] = mg_cmd_color | elt->triangleIndex;
-						tileArray[count].triangleIndex = elt->triangleIndex;
 						count++;
 						continue;
 					}
@@ -328,8 +328,7 @@ kernel void GatherKernel(const device mg_shape_queue* shapeQueueBuffer [[buffer(
 				elt = &eltBuffer[eltIndex];
 				eltIndex = elt->next;
 
-				tileArray[count].kind = mg_cmd_triangle;
+				tileArray[count] = elt->triangleIndex;
-				tileArray[count].triangleIndex = elt->triangleIndex;
 				count++;
 			}
 		}
@@ -420,10 +419,13 @@ kernel void RenderKernel(const device uint* tileCounters [[buffer(0)]],
 
     for(uint tileArrayIndex=0; tileArrayIndex < tileCounter; tileArrayIndex++)
     {
-		const device mg_tile_cmd* cmd = &tileArrayBuffer[RENDERER_TILE_BUFFER_COUNT * tileIndex + tileArrayIndex];
+		mg_tile_cmd cmd = tileArrayBuffer[RENDERER_TILE_BUFFER_COUNT * tileIndex + tileArrayIndex];
-		const device mg_triangle_data* triangle = &triangleArray[cmd->triangleIndex];
 
-		if(cmd->kind == mg_cmd_color)
+		int cmdKind = cmd & MG_TILE_CMD_MASK;
+		int triangleIndex = cmd & ~(MG_TILE_CMD_MASK);
+		const device mg_triangle_data* triangle = &triangleArray[triangleIndex];
+
+		if(cmdKind == mg_cmd_color)
 		{
 			for(int sampleIndex=0; sampleIndex<sampleCount; sampleIndex++)
 			{
@@ -432,7 +434,7 @@ kernel void RenderKernel(const device uint* tileCounters [[buffer(0)]],
 				currentShapeIndex[sampleIndex] = triangle->shapeIndex;
 			}
 		}
-		else if(cmd->kind == mg_cmd_triangle)
+		else
 		{
 			int2 p0 = triangle->p0;
 			int2 p1 = triangle->p1;