Prefer sRGB formats by default, as per spec

src/gpu/vulkan/SDL_gpu_vulkan.c

@@ -145,6 +145,34 @@ static VkPresentModeKHR SDLToVK_PresentMode[] = {
     VK_PRESENT_MODE_MAILBOX_KHR
 };
 
+typedef struct TextureFormatPair {
+    VkFormat vk;
+    SDL_GPUTextureFormat sdl;
+} TextureFormatPair;
+
+static TextureFormatPair SDLToVK_TextureFormat_SrgbOnly[] = {
+    {VK_FORMAT_R8G8B8A8_SRGB, SDL_GPU_TEXTUREFORMAT_R8G8B8A8_UNORM_SRGB},
+    {VK_FORMAT_B8G8R8A8_SRGB, SDL_GPU_TEXTUREFORMAT_B8G8R8A8_UNORM_SRGB},
+    {VK_FORMAT_BC1_RGBA_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_BC1_RGBA_UNORM_SRGB},
+    {VK_FORMAT_BC2_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_BC2_RGBA_UNORM_SRGB},
+    {VK_FORMAT_BC3_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_BC3_RGBA_UNORM_SRGB},
+    {VK_FORMAT_BC7_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_BC7_RGBA_UNORM_SRGB},
+    {VK_FORMAT_ASTC_4x4_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_4x4_UNORM_SRGB},
+    {VK_FORMAT_ASTC_5x4_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_5x4_UNORM_SRGB},
+    {VK_FORMAT_ASTC_5x5_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_5x5_UNORM_SRGB},
+    {VK_FORMAT_ASTC_6x5_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_6x5_UNORM_SRGB},
+    {VK_FORMAT_ASTC_6x6_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_6x6_UNORM_SRGB},
+    {VK_FORMAT_ASTC_8x5_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_8x5_UNORM_SRGB},
+    {VK_FORMAT_ASTC_8x6_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_8x6_UNORM_SRGB},
+    {VK_FORMAT_ASTC_8x8_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_8x8_UNORM_SRGB},
+    {VK_FORMAT_ASTC_10x5_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_10x5_UNORM_SRGB},
+    {VK_FORMAT_ASTC_10x6_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_10x6_UNORM_SRGB},
+    {VK_FORMAT_ASTC_10x8_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_10x8_UNORM_SRGB},
+    {VK_FORMAT_ASTC_10x10_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_10x10_UNORM_SRGB},
+    {VK_FORMAT_ASTC_12x10_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_12x10_UNORM_SRGB},
+    {VK_FORMAT_ASTC_12x12_SRGB_BLOCK, SDL_GPU_TEXTUREFORMAT_ASTC_12x12_UNORM_SRGB},
+};
+
 static VkFormat SDLToVK_TextureFormat[] = {
     VK_FORMAT_UNDEFINED,                   // INVALID
     VK_FORMAT_R8_UNORM,                    // A8_UNORM
@@ -6817,6 +6845,21 @@ static XrResult VULKAN_DestroyXRSwapchain(
     return renderer->xr->xrDestroySwapchain(swapchain);
 }
 
+static bool VULKAN_INTERNAL_FindXRSrgbSwapchain(int64_t *supportedFormats, Uint32 numFormats, SDL_GPUTextureFormat *sdlFormat, int64_t *vkFormat)
+{
+    for(Uint32 i = 0; i < SDL_arraysize(SDLToVK_TextureFormat_SrgbOnly); i++) {
+        for(Uint32 j = 0; j < numFormats; j++) {
+            if(SDLToVK_TextureFormat_SrgbOnly[i].vk == supportedFormats[j]) {
+                *sdlFormat = SDLToVK_TextureFormat_SrgbOnly[i].sdl;
+                *vkFormat = SDLToVK_TextureFormat_SrgbOnly[i].vk;
+                return true;
+            }
+        }
+    }  
+
+    return false;
+}
+
 static XrResult VULKAN_CreateXRSwapchain(
     SDL_GPURenderer *driverData,
     XrSession session,
@@ -6842,34 +6885,37 @@ static XrResult VULKAN_CreateXRSwapchain(
         return result;
     }
 
-    int64_t format = VK_FORMAT_UNDEFINED;
-    /* Iterate over all formats the runtime support */
-    for(i = 0; i < num_supported_formats && format == VK_FORMAT_UNDEFINED; i++)
-    {
-        /* Iterate over all formats we support */
-        for(j = 0; j < SDL_arraysize(SDLToVK_TextureFormat); j++)
+    int64_t vkFormat = VK_FORMAT_UNDEFINED;
+    /* The OpenXR spec reccomends applications not submit linear data, so let's try to explicitly find an sRGB swapchain before we search the whole list */
+    if (!VULKAN_INTERNAL_FindXRSrgbSwapchain(supported_formats, num_supported_formats, textureFormat, &vkFormat)) {
+        /* Iterate over all formats the runtime support */
+        for(i = 0; i < num_supported_formats && vkFormat == VK_FORMAT_UNDEFINED; i++)
         {
-            /* Pick the first format the runtime wants that we also support, the runtime should return these in order of preference */
-            if(SDLToVK_TextureFormat[j] == supported_formats[j])
+            /* Iterate over all formats we support */
+            for(j = 0; j < SDL_arraysize(SDLToVK_TextureFormat); j++)
             {
-                format = supported_formats[j];
-                *textureFormat = j;
-                break;
+                /* Pick the first format the runtime wants that we also support, the runtime should return these in order of preference */
+                if(SDLToVK_TextureFormat[j] == supported_formats[j])
+                {
+                    vkFormat = supported_formats[j];
+                    *textureFormat = j;
+                    break;
+                }
             }
         }
     }
 
     SDL_stack_free(num_supported_formats);
 
-    if(format == VK_FORMAT_UNDEFINED)
+    if(vkFormat == VK_FORMAT_UNDEFINED)
     {
         /* TODO: there needs to be a better way of returning SDL errors from here... */
         SDL_SetError("Failed to find swapchain format supported by both the OpenXR runtime and SDL_gpu");
         return XR_ERROR_RUNTIME_FAILURE;
     }
 
     XrSwapchainCreateInfo createInfo = *oldCreateInfo;
-    createInfo.format = format;
+    createInfo.format = vkFormat;
 
     /* TODO: validate createInfo.usageFlags */
 
@@ -6935,11 +6981,11 @@ static XrResult VULKAN_CreateXRSwapchain(
                         texture,
                         i,
                         j,
-                        format,
+                        vkFormat,
                         texture->swizzle,
                         &texture->subresources[subresourceIndex].renderTargetViews[0])) {
                         VULKAN_INTERNAL_DestroyTexture(renderer, texture);
-                        SDL_Log("piss and shit\n");
+                        SDL_SetError("Failed to create render target view\n");
                         return XR_ERROR_RUNTIME_FAILURE; /* TODO: there's probably a better error for this.. */
                     }
                 }