transfer buffers specify upload or download usage

Author: thatcosmonaut

include/SDL3/SDL_gpu.h

@@ -177,6 +177,12 @@ typedef enum SDL_GpuBufferUsageFlagBits
 
 typedef Uint32 SDL_GpuBufferUsageFlags;
 
+typedef enum SDL_GpuTransferBufferUsage
+{
+    SDL_GPU_TRANSFERBUFFERUSAGE_UPLOAD,
+    SDL_GPU_TRANSFERBUFFERUSAGE_DOWNLOAD
+} SDL_GpuTransferBufferUsage;
+
 typedef enum SDL_GpuShaderStage
 {
     SDL_GPU_SHADERSTAGE_VERTEX,
@@ -936,7 +942,7 @@ extern SDL_DECLSPEC SDL_GpuBuffer *SDLCALL SDL_GpuCreateBuffer(
  * Creates a transfer buffer to be used when uploading to or downloading from graphics resources.
  *
  * \param device a GPU Context
- * \param uploadOnly specifies that the transfer buffer will only be used for uploads, allows optimizations on certain backends
+ * \param usage whether the transfer buffer will be used for uploads or downloads
  * \param sizeInBytes the size of the transfer buffer
  * \returns a transfer buffer on success, or NULL on failure
  *
@@ -950,7 +956,7 @@ extern SDL_DECLSPEC SDL_GpuBuffer *SDLCALL SDL_GpuCreateBuffer(
  */
 extern SDL_DECLSPEC SDL_GpuTransferBuffer *SDLCALL SDL_GpuCreateTransferBuffer(
     SDL_GpuDevice *device,
-    SDL_bool uploadOnly,
+    SDL_GpuTransferBufferUsage usage,
     Uint32 sizeInBytes);
 
 /* Debug Naming */

src/dynapi/SDL_dynapi_procs.h

@@ -1060,7 +1060,7 @@ SDL_DYNAPI_PROC(SDL_GpuSampler*,SDL_GpuCreateSampler,(SDL_GpuDevice *a, SDL_GpuS
 SDL_DYNAPI_PROC(SDL_GpuShader*,SDL_GpuCreateShader,(SDL_GpuDevice *a, SDL_GpuShaderCreateInfo *b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_GpuTexture*,SDL_GpuCreateTexture,(SDL_GpuDevice *a, SDL_GpuTextureCreateInfo *b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_GpuBuffer*,SDL_GpuCreateBuffer,(SDL_GpuDevice *a, SDL_GpuBufferUsageFlags b, Uint32 c),(a,b,c),return)
-SDL_DYNAPI_PROC(SDL_GpuTransferBuffer*,SDL_GpuCreateTransferBuffer,(SDL_GpuDevice *a, SDL_bool b, Uint32 c),(a,b,c),return)
+SDL_DYNAPI_PROC(SDL_GpuTransferBuffer*,SDL_GpuCreateTransferBuffer,(SDL_GpuDevice *a, SDL_GpuTransferBufferUsage b, Uint32 c),(a,b,c),return)
 SDL_DYNAPI_PROC(void,SDL_GpuSetBufferName,(SDL_GpuDevice *a, SDL_GpuBuffer *b, const char *c),(a,b,c),)
 SDL_DYNAPI_PROC(void,SDL_GpuSetTextureName,(SDL_GpuDevice *a, SDL_GpuTexture *b, const char *c),(a,b,c),)
 SDL_DYNAPI_PROC(void,SDL_GpuSetStringMarker,(SDL_GpuCommandBuffer *a, const char *b),(a,b),)

src/gpu/SDL_gpu.c

@@ -444,13 +444,13 @@ SDL_GpuBuffer *SDL_GpuCreateBuffer(
 
 SDL_GpuTransferBuffer *SDL_GpuCreateTransferBuffer(
     SDL_GpuDevice *device,
-    SDL_bool uploadOnly,
+    SDL_GpuTransferBufferUsage usage,
     Uint32 sizeInBytes)
 {
     NULL_ASSERT(device)
     return device->CreateTransferBuffer(
         device->driverData,
-        uploadOnly,
+        usage,
         sizeInBytes);
 }
 

src/gpu/SDL_gpu_driver.h

@@ -231,7 +231,7 @@ struct SDL_GpuDevice
 
     SDL_GpuTransferBuffer *(*CreateTransferBuffer)(
         SDL_GpuRenderer *driverData,
-        SDL_bool uploadOnly,
+        SDL_GpuTransferBufferUsage usage,
         Uint32 sizeInBytes);
 
     /* Debug Naming */

src/gpu/vulkan/SDL_gpu_vulkan.c

@@ -6766,7 +6766,7 @@ static VulkanUniformBuffer *VULKAN_INTERNAL_CreateUniformBuffer(
 
 static SDL_GpuTransferBuffer *VULKAN_CreateTransferBuffer(
     SDL_GpuRenderer *driverData,
-    SDL_bool uploadOnly, /* ignored on Vulkan */
+    SDL_GpuTransferBufferUsage usage, /* ignored on Vulkan */
     Uint32 sizeInBytes)
 {
     return (SDL_GpuTransferBuffer *)VULKAN_INTERNAL_CreateBufferContainer(