Fix GetSampler() bug for INDEX8 pixel format (#15099)

src/render/direct3d11/SDL_render_d3d11.c

@@ -2395,6 +2395,11 @@ static bool D3D11_SetDrawState(SDL_Renderer *renderer, const SDL_RenderCommand *
 
 static ID3D11SamplerState *D3D11_GetSamplerState(D3D11_RenderData *data, SDL_PixelFormat format, SDL_ScaleMode scale_mode, SDL_TextureAddressMode address_u, SDL_TextureAddressMode address_v)
 {
+    if (format == SDL_PIXELFORMAT_INDEX8) {
+        // We'll do linear sampling in the shader if needed
+        scale_mode = SDL_SCALEMODE_NEAREST;
+    }
+
     Uint32 key = RENDER_SAMPLER_HASHKEY(scale_mode, address_u, address_v);
     SDL_assert(key < SDL_arraysize(data->samplers));
     if (!data->samplers[key]) {
@@ -2412,12 +2417,7 @@ static ID3D11SamplerState *D3D11_GetSamplerState(D3D11_RenderData *data, SDL_Pix
             break;
         case SDL_SCALEMODE_PIXELART:    // Uses linear sampling
         case SDL_SCALEMODE_LINEAR:
-            if (format == SDL_PIXELFORMAT_INDEX8) {
-                // We'll do linear sampling in the shader
-                samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_POINT;
-            } else {
-                samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
-            }
+            samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
             break;
         default:
             SDL_SetError("Unknown scale mode: %d", scale_mode);

src/render/direct3d12/SDL_render_d3d12.c

@@ -2838,6 +2838,11 @@ static bool D3D12_SetDrawState(SDL_Renderer *renderer, const SDL_RenderCommand *
 
 static D3D12_CPU_DESCRIPTOR_HANDLE *D3D12_GetSamplerState(D3D12_RenderData *data, SDL_PixelFormat format, SDL_ScaleMode scale_mode, SDL_TextureAddressMode address_u, SDL_TextureAddressMode address_v)
 {
+    if (format == SDL_PIXELFORMAT_INDEX8) {
+        // We'll do linear sampling in the shader if needed
+        scale_mode = SDL_SCALEMODE_NEAREST;
+    }
+
     Uint32 key = RENDER_SAMPLER_HASHKEY(scale_mode, address_u, address_v);
     SDL_assert(key < SDL_arraysize(data->samplers));
     if (!data->samplers_created[key]) {
@@ -2863,12 +2868,7 @@ static D3D12_CPU_DESCRIPTOR_HANDLE *D3D12_GetSamplerState(D3D12_RenderData *data
             break;
         case SDL_SCALEMODE_PIXELART:    // Uses linear sampling
         case SDL_SCALEMODE_LINEAR:
-            if (format == SDL_PIXELFORMAT_INDEX8) {
-                // We'll do linear sampling in the shader
-                samplerDesc.Filter = D3D12_FILTER_MIN_MAG_MIP_POINT;
-            } else {
-                samplerDesc.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
-            }
+            samplerDesc.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
             break;
         default:
             SDL_SetError("Unknown scale mode: %d", scale_mode);

src/render/gpu/SDL_render_gpu.c

@@ -790,6 +790,11 @@ static void SetViewportAndScissor(GPU_RenderData *data)
 
 static SDL_GPUSampler *GetSampler(GPU_RenderData *data, SDL_PixelFormat format, SDL_ScaleMode scale_mode, SDL_TextureAddressMode address_u, SDL_TextureAddressMode address_v)
 {
+    if (format == SDL_PIXELFORMAT_INDEX8) {
+        // We'll do linear sampling in the shader if needed
+        scale_mode = SDL_SCALEMODE_NEAREST;
+    }
+
     Uint32 key = RENDER_SAMPLER_HASHKEY(scale_mode, address_u, address_v);
     SDL_assert(key < SDL_arraysize(data->samplers));
     if (!data->samplers[key]) {
@@ -803,16 +808,9 @@ static SDL_GPUSampler *GetSampler(GPU_RenderData *data, SDL_PixelFormat format,
             break;
         case SDL_SCALEMODE_PIXELART:    // Uses linear sampling
         case SDL_SCALEMODE_LINEAR:
-            if (format == SDL_PIXELFORMAT_INDEX8) {
-                // We'll do linear sampling in the shader
-                sci.min_filter = SDL_GPU_FILTER_NEAREST;
-                sci.mag_filter = SDL_GPU_FILTER_NEAREST;
-                sci.mipmap_mode = SDL_GPU_SAMPLERMIPMAPMODE_NEAREST;
-            } else {
-                sci.min_filter = SDL_GPU_FILTER_LINEAR;
-                sci.mag_filter = SDL_GPU_FILTER_LINEAR;
-                sci.mipmap_mode = SDL_GPU_SAMPLERMIPMAPMODE_LINEAR;
-            }
+            sci.min_filter = SDL_GPU_FILTER_LINEAR;
+            sci.mag_filter = SDL_GPU_FILTER_LINEAR;
+            sci.mipmap_mode = SDL_GPU_SAMPLERMIPMAPMODE_LINEAR;
             break;
         default:
             SDL_SetError("Unknown scale mode: %d", scale_mode);

src/render/metal/SDL_render_metal.m

@@ -1584,6 +1584,11 @@ static bool SetDrawState(SDL_Renderer *renderer, const SDL_RenderCommand *cmd, c
 
 static id<MTLSamplerState> GetSampler(SDL3METAL_RenderData *data, SDL_PixelFormat format, SDL_ScaleMode scale_mode, SDL_TextureAddressMode address_u, SDL_TextureAddressMode address_v)
 {
+    if (format == SDL_PIXELFORMAT_INDEX8) {
+        // We'll do linear sampling in the shader if needed
+        scale_mode = SDL_SCALEMODE_NEAREST;
+    }
+
     NSNumber *key = [NSNumber numberWithInteger:RENDER_SAMPLER_HASHKEY(scale_mode, address_u, address_v)];
     id<MTLSamplerState> mtlsampler = data.mtlsamplers[key];
     if (mtlsampler == nil) {
@@ -1596,14 +1601,8 @@ static id<MTLSamplerState> GetSampler(SDL3METAL_RenderData *data, SDL_PixelForma
             break;
         case SDL_SCALEMODE_PIXELART:    // Uses linear sampling
         case SDL_SCALEMODE_LINEAR:
-            if (format == SDL_PIXELFORMAT_INDEX8) {
-                // We'll do linear sampling in the shader
-                samplerdesc.minFilter = MTLSamplerMinMagFilterNearest;
-                samplerdesc.magFilter = MTLSamplerMinMagFilterNearest;
-            } else {
-                samplerdesc.minFilter = MTLSamplerMinMagFilterLinear;
-                samplerdesc.magFilter = MTLSamplerMinMagFilterLinear;
-            }
+            samplerdesc.minFilter = MTLSamplerMinMagFilterLinear;
+            samplerdesc.magFilter = MTLSamplerMinMagFilterLinear;
             break;
         default:
             SDL_SetError("Unknown scale mode: %d", scale_mode);

src/render/vulkan/SDL_render_vulkan.c

@@ -3870,6 +3870,11 @@ static bool VULKAN_SetDrawState(SDL_Renderer *renderer, const SDL_RenderCommand
 
 static VkSampler VULKAN_GetSampler(VULKAN_RenderData *data, SDL_PixelFormat format, SDL_ScaleMode scale_mode, SDL_TextureAddressMode address_u, SDL_TextureAddressMode address_v)
 {
+    if (format == SDL_PIXELFORMAT_INDEX8) {
+        // We'll do linear sampling in the shader if needed
+        scale_mode = SDL_SCALEMODE_NEAREST;
+    }
+
     Uint32 key = RENDER_SAMPLER_HASHKEY(scale_mode, address_u, address_v);
     SDL_assert(key < SDL_arraysize(data->samplers));
     if (!data->samplers[key]) {
@@ -3889,14 +3894,8 @@ static VkSampler VULKAN_GetSampler(VULKAN_RenderData *data, SDL_PixelFormat form
             break;
         case SDL_SCALEMODE_PIXELART:    // Uses linear sampling
         case SDL_SCALEMODE_LINEAR:
-            if (format == SDL_PIXELFORMAT_INDEX8) {
-                // We'll do linear sampling in the shader
-                samplerCreateInfo.magFilter = VK_FILTER_NEAREST;
-                samplerCreateInfo.minFilter = VK_FILTER_NEAREST;
-            } else {
-                samplerCreateInfo.magFilter = VK_FILTER_LINEAR;
-                samplerCreateInfo.minFilter = VK_FILTER_LINEAR;
-            }
+            samplerCreateInfo.magFilter = VK_FILTER_LINEAR;
+            samplerCreateInfo.minFilter = VK_FILTER_LINEAR;
             break;
         default:
             SDL_SetError("Unknown scale mode: %d", scale_mode);