SDL backend viewport fix

Author: thatcosmonaut

src/FNA3D_Driver_SDL.c

@@ -1142,6 +1142,7 @@ typedef struct SDLGPU_Renderer
     uint8_t needFragmentSamplerBind;
 
     /* Pipeline state */
+
     FNA3D_BlendState fnaBlendState;
     FNA3D_RasterizerState fnaRasterizerState;
     FNA3D_DepthStencilState fnaDepthStencilState;
@@ -1156,6 +1157,10 @@ typedef struct SDLGPU_Renderer
     uint8_t hasDepthStencilAttachment;
     SDL_GpuTextureFormat depthStencilFormat;
 
+    /* Viewport state */
+
+    FNA3D_Viewport viewport;
+
     /* Presentation structure */
 
     void *mainWindowHandle;
@@ -1194,6 +1199,9 @@ typedef struct SDLGPU_Renderer
     MOJOSHADER_effect *currentEffect;
     const MOJOSHADER_effectTechnique *currentTechnique;
     uint32_t currentPass;
+
+    /* Capabilities */
+    uint8_t supportsBaseVertex;
 } SDLGPU_Renderer;
 
 /* Statics */
@@ -1440,6 +1448,28 @@ static void SDLGPU_INTERNAL_GetTextureData(
 
 /* Drawing */
 
+static void SDLGPU_INTERNAL_SetViewport(
+    SDLGPU_Renderer *renderer
+) {
+    SDL_GpuViewport gpuViewport;
+
+    /* Flipping the viewport for compatibility with D3D */
+    gpuViewport.x = (float) renderer->viewport.x;
+    gpuViewport.w = (float) renderer->viewport.w;
+    gpuViewport.minDepth = renderer->viewport.minDepth;
+    gpuViewport.maxDepth = renderer->viewport.maxDepth;
+
+    /* FIXME: moltenVK hack */
+    gpuViewport.y = (float) renderer->viewport.y + renderer->viewport.h;
+    gpuViewport.h = (float) -renderer->viewport.h;
+
+    SDL_GpuSetViewport(
+        renderer->device,
+        renderer->commandBuffer,
+        &gpuViewport
+    );
+}
+
 static void SDLGPU_INTERNAL_PrepareRenderPassClear(
 	SDLGPU_Renderer *renderer,
 	FNA3D_Vec4 *color,
@@ -2092,6 +2122,9 @@ static void SDLGPU_INTERNAL_BindGraphicsPipeline(
     renderer->needVertexSamplerBind = 1;
     renderer->needVertexBufferBind = 1;
     renderer->indexBufferBinding.gpuBuffer = NULL;
+
+    /* Force viewport for D3D compatibility hack */
+    SDLGPU_INTERNAL_SetViewport(renderer);
 }
 
 static SDL_GpuSampler* SDLGPU_INTERNAL_FetchSamplerState(
@@ -2247,6 +2280,11 @@ static void SDLGPU_ApplyVertexBufferBindings(
     int32_t i, bindingsIndex;
     uint32_t hash;
 
+    if (renderer->supportsBaseVertex)
+    {
+        baseVertex = 0;
+    }
+
     /* link/compile shader program if it hasn't been yet */
     if (!MOJOSHADER_sdlCheckProgramStatus(renderer->mojoshaderContext))
     {
@@ -2321,20 +2359,17 @@ static void SDLGPU_SetViewport(
 	FNA3D_Viewport *viewport
 ) {
     SDLGPU_Renderer *renderer = (SDLGPU_Renderer*) driverData;
-    SDL_GpuViewport gpuViewport;
 
-    gpuViewport.x = (float) viewport->x;
-    gpuViewport.y = (float) viewport->y;
-    gpuViewport.w = (float) viewport->w;
-    gpuViewport.h = (float) viewport->h;
-    gpuViewport.minDepth = viewport->minDepth;
-    gpuViewport.maxDepth = viewport->maxDepth;
-
-    SDL_GpuSetViewport(
-        renderer->device,
-        renderer->commandBuffer,
-        &gpuViewport
-    );
+    if (	viewport->x != renderer->viewport.x ||
+		viewport->y != renderer->viewport.y ||
+		viewport->w != renderer->viewport.w ||
+		viewport->h != renderer->viewport.h ||
+		viewport->minDepth != renderer->viewport.minDepth ||
+		viewport->maxDepth != renderer->viewport.maxDepth	)
+	{
+		renderer->viewport = *viewport;
+		SDLGPU_INTERNAL_SetViewport(renderer);
+	}
 }
 
 static void SDLGPU_SetScissorRect(
@@ -4102,6 +4137,9 @@ static FNA3D_Device* SDLGPU_CreateDevice(
         NULL
     );
 
+    /* FIXME: moltenVK fix */
+    renderer->supportsBaseVertex = 1;
+
     /* Acquire command buffer, we are ready for takeoff */
 
     SDLGPU_ResetCommandBufferState(renderer);