modify readback API

include/Refresh.h

@@ -1193,46 +1193,6 @@ REFRESHAPI void Refresh_UploadToBuffer(
 	Refresh_WriteOptions writeOption
 );
 
-/* GPU-to-CPU copies occur on the GPU timeline.
- *
- * You may NOT assume that the data in the TransferBuffer is fully copied
- * until the command buffer has finished execution.
- */
-
-/*
- * transferOption:
- *  SAFEDISCARD:
- *    If this TransferBuffer has been used in commands that have not completed,
- *    the issued commands will still be valid at the cost of increased memory usage.
- *    You may NOT assume that any of the previous data is retained.
- *    If the TransferBuffer was not in use, this option is equivalent to OVERWRITE.
- *    It is not recommended to use this option with large TransferBuffers.
- *
- *  OVERWRITE:
- *    Overwrites the data regardless of whether a command has been issued.
- *    Use this option with great care, as it can cause data races to occur!
- */
-
-/* Downloads data from a texture to a TransferBuffer. */
-REFRESHAPI void Refresh_DownloadFromTexture(
-	Refresh_Device *device,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_TextureRegion *textureRegion,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferImageCopy *copyParams,
-	Refresh_TransferOptions transferOption
-);
-
-/* Downloads data from a GpuBuffer object. */
-REFRESHAPI void Refresh_DownloadFromBuffer(
-	Refresh_Device *device,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_GpuBuffer *gpuBuffer,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferCopy *copyParams,
-	Refresh_TransferOptions transferOption
-);
-
 /* GPU-to-GPU copies occur on the GPU timeline,
  * and you may assume the copy has finished in subsequent commands.
  */
@@ -1401,6 +1361,49 @@ REFRESHAPI void Refresh_ReleaseFence(
 	Refresh_Fence *fence
 );
 
+/* Readback */
+
+/* GPU-to-CPU copies occur immediately on the CPU timeline.
+ *
+ * If you modify data on the GPU and then call these functions without calling Wait or WaitForFences first,
+ * the data will be undefined!
+ *
+ * Readback forces a sync point and is generally a bad thing to do.
+ * Only use these functions if you have exhausted all other options.
+ */
+
+/*
+ * transferOption:
+ *  SAFEDISCARD:
+ *    If this TransferBuffer has been used in commands that have not completed,
+ *    the issued commands will still be valid at the cost of increased memory usage.
+ *    You may NOT assume that any of the previous data is retained.
+ *    If the TransferBuffer was not in use, this option is equivalent to OVERWRITE.
+ *    It is not recommended to use this option with large TransferBuffers.
+ *
+ *  OVERWRITE:
+ *    Overwrites the data regardless of whether a command has been issued.
+ *    Use this option with great care, as it can cause data races to occur!
+ */
+
+/* Downloads data from a texture to a TransferBuffer. */
+REFRESHAPI void Refresh_DownloadFromTexture(
+	Refresh_Device *device,
+	Refresh_TextureRegion *textureRegion,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferImageCopy *copyParams,
+	Refresh_TransferOptions transferOption
+);
+
+/* Downloads data from a GpuBuffer object. */
+REFRESHAPI void Refresh_DownloadFromBuffer(
+	Refresh_Device *device,
+	Refresh_GpuBuffer *gpuBuffer,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferCopy *copyParams,
+	Refresh_TransferOptions transferOption
+);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */

src/Refresh.c

@@ -824,44 +824,6 @@ void Refresh_UploadToBuffer(
 	);
 }
 
-void Refresh_DownloadFromTexture(
-	Refresh_Device *device,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_TextureRegion *textureRegion,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferImageCopy *copyParams,
-	Refresh_TransferOptions transferOption
-) {
-	NULL_RETURN(device);
-	device->DownloadFromTexture(
-		device->driverData,
-		commandBuffer,
-		textureRegion,
-		transferBuffer,
-		copyParams,
-		transferOption
-	);
-}
-
-void Refresh_DownloadFromBuffer(
-	Refresh_Device *device,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_GpuBuffer *gpuBuffer,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferCopy *copyParams,
-	Refresh_TransferOptions transferOption
-) {
-	NULL_RETURN(device);
-	device->DownloadFromBuffer(
-		device->driverData,
-		commandBuffer,
-		gpuBuffer,
-		transferBuffer,
-		copyParams,
-		transferOption
-	);
-}
-
 void Refresh_CopyTextureToTexture(
 	Refresh_Device *device,
 	Refresh_CommandBuffer *commandBuffer,
@@ -1067,4 +1029,38 @@ void Refresh_ReleaseFence(
 	);
 }
 
+void Refresh_DownloadFromTexture(
+	Refresh_Device *device,
+	Refresh_TextureRegion *textureRegion,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferImageCopy *copyParams,
+	Refresh_TransferOptions transferOption
+) {
+	NULL_RETURN(device);
+	device->DownloadFromTexture(
+		device->driverData,
+		textureRegion,
+		transferBuffer,
+		copyParams,
+		transferOption
+	);
+}
+
+void Refresh_DownloadFromBuffer(
+	Refresh_Device *device,
+	Refresh_GpuBuffer *gpuBuffer,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferCopy *copyParams,
+	Refresh_TransferOptions transferOption
+) {
+	NULL_RETURN(device);
+	device->DownloadFromBuffer(
+		device->driverData,
+		gpuBuffer,
+		transferBuffer,
+		copyParams,
+		transferOption
+	);
+}
+
 /* vim: set noexpandtab shiftwidth=8 tabstop=8: */

src/Refresh_Driver.h

@@ -506,24 +506,6 @@ struct Refresh_Device
 		Refresh_WriteOptions writeOption
 	);
 
-	void (*DownloadFromTexture)(
-		Refresh_Renderer *driverData,
-		Refresh_CommandBuffer *commandBuffer,
-		Refresh_TextureRegion *textureSlice,
-		Refresh_TransferBuffer *transferBuffer,
-		Refresh_BufferImageCopy *copyParams,
-		Refresh_TransferOptions transferOption
-	);
-
-	void (*DownloadFromBuffer)(
-		Refresh_Renderer *driverData,
-		Refresh_CommandBuffer *commandBuffer,
-		Refresh_GpuBuffer *gpuBuffer,
-		Refresh_TransferBuffer *transferBuffer,
-		Refresh_BufferCopy *copyParams,
-		Refresh_TransferOptions transferOption
-	);
-
 	void (*CopyTextureToTexture)(
 		Refresh_Renderer *driverData,
 		Refresh_CommandBuffer *commandBuffer,
@@ -619,6 +601,22 @@ struct Refresh_Device
 		Refresh_Fence *fence
 	);
 
+	void (*DownloadFromTexture)(
+		Refresh_Renderer *driverData,
+		Refresh_TextureRegion *textureSlice,
+		Refresh_TransferBuffer *transferBuffer,
+		Refresh_BufferImageCopy *copyParams,
+		Refresh_TransferOptions transferOption
+	);
+
+	void (*DownloadFromBuffer)(
+		Refresh_Renderer *driverData,
+		Refresh_GpuBuffer *gpuBuffer,
+		Refresh_TransferBuffer *transferBuffer,
+		Refresh_BufferCopy *copyParams,
+		Refresh_TransferOptions transferOption
+	);
+
 	/* Opaque pointer for the Driver */
 	Refresh_Renderer *driverData;
 };

src/Refresh_Driver_D3D11.c

@@ -2069,14 +2069,12 @@ static void D3D11_UploadToBuffer(
 
 static void D3D11_DownloadFromTexture(
 	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
 	Refresh_TextureRegion *textureRegion,
 	Refresh_TransferBuffer *transferBuffer,
 	Refresh_BufferImageCopy *copyParams,
 	Refresh_TransferOptions transferOption
 ) {
 	D3D11Renderer *renderer = (D3D11Renderer*) driverData;
-	D3D11CommandBuffer *d3d11CommandBuffer = (D3D11CommandBuffer*) commandBuffer;
 	D3D11TransferBufferContainer *container = (D3D11TransferBufferContainer*) transferBuffer;
 	D3D11TransferBuffer *d3d11TransferBuffer = container->activeBuffer;
 	D3D11Texture *d3d11Texture = (D3D11Texture*) textureRegion->textureSlice.texture;
@@ -2126,8 +2124,10 @@ static void D3D11_DownloadFromTexture(
 	);
 	ERROR_CHECK_RETURN("Staging texture creation failed",)
 
-	ID3D11DeviceContext1_CopySubresourceRegion1(
+	/* Readback is only possible on CPU timeline in D3D11 */
-		d3d11CommandBuffer->context,
+	SDL_LockMutex(renderer->contextLock);
+	ID3D11DeviceContext_CopySubresourceRegion(
+		renderer->immediateContext,
 		stagingTexture,
 		0,
 		0,
@@ -2135,13 +2135,12 @@ static void D3D11_DownloadFromTexture(
 		0,
 		d3d11Texture->handle,
 		subresourceIndex,
-		&srcBox,
+		&srcBox
-		D3D11_COPY_NO_OVERWRITE
 	);
 
 	/* Read from the staging texture */
-	res = ID3D11DeviceContext1_Map(
+	res = ID3D11DeviceContext_Map(
-		d3d11CommandBuffer->context,
+		renderer->immediateContext,
 		stagingTexture,
 		subresourceIndex,
 		D3D11_MAP_READ,
@@ -2170,24 +2169,24 @@ static void D3D11_DownloadFromTexture(
 	}
 
 	ID3D11DeviceContext1_Unmap(
-		d3d11CommandBuffer->context,
+		renderer->immediateContext,
 		stagingTexture,
 		0
 	);
+	SDL_UnlockMutex(renderer->contextLock);
 
+	/* Clean up the staging texture */
 	ID3D11Texture2D_Release(stagingTexture);
 }
 
 static void D3D11_DownloadFromBuffer(
 	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
 	Refresh_GpuBuffer *gpuBuffer,
 	Refresh_TransferBuffer *transferBuffer,
 	Refresh_BufferCopy *copyParams,
 	Refresh_TransferOptions transferOption
 ) {
 	D3D11Renderer *renderer = (D3D11Renderer*) driverData;
-	D3D11CommandBuffer *d3d11CommandBuffer = (D3D11CommandBuffer*) commandBuffer;
 	D3D11TransferBufferContainer *container = (D3D11TransferBufferContainer*) transferBuffer;
 	D3D11TransferBuffer *d3d11TransferBuffer = container->activeBuffer;
 	D3D11Buffer *d3d11Buffer = (D3D11Buffer*) gpuBuffer;
@@ -2225,8 +2224,10 @@ static void D3D11_DownloadFromBuffer(
 	);
 	ERROR_CHECK_RETURN("Could not create staging buffer for readback", );
 
-	ID3D11DeviceContext1_CopySubresourceRegion1(
+	/* Readback is only possible on CPU timeline in D3D11 */
-		d3d11CommandBuffer->context,
+	SDL_LockMutex(renderer->contextLock);
+	ID3D11DeviceContext_CopySubresourceRegion(
+		renderer->immediateContext,
 		(ID3D11Resource*) stagingBuffer,
 		0,
 		0,
@@ -2234,13 +2235,12 @@ static void D3D11_DownloadFromBuffer(
 		0,
 	 	(ID3D11Resource*) d3d11Buffer->handle,
 		0,
-		&srcBox,
+		&srcBox
-		D3D11_COPY_NO_OVERWRITE
 	);
 
 	/* Read from the staging buffer */
-	res = ID3D11DeviceContext1_Map(
+	res = ID3D11DeviceContext_Map(
-		d3d11CommandBuffer->context,
+		renderer->immediateContext,
 		stagingBuffer,
 		0,
 		D3D11_MAP_READ,
@@ -2265,12 +2265,11 @@ static void D3D11_DownloadFromBuffer(
 	);
 
 	ID3D11DeviceContext1_Unmap(
-		d3d11CommandBuffer->context,
+		renderer->immediateContext,
 		stagingBuffer,
 		0
 	);
-
+	SDL_UnlockMutex(renderer->contextLock);
-	D3D11_INTERNAL_TrackTransferBuffer(d3d11CommandBuffer, d3d11TransferBuffer);
 
 	/* Clean up the staging buffer */
 	ID3D11Buffer_Release(stagingBuffer);

src/Refresh_Driver_Vulkan.c

@@ -8550,130 +8550,6 @@ static void VULKAN_UploadToBuffer(
 	VULKAN_INTERNAL_TrackCopiedBuffer(renderer, vulkanCommandBuffer, gpuBufferContainer->activeBufferHandle->vulkanBuffer);
 }
 
-static void VULKAN_DownloadFromTexture(
-	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_TextureRegion *textureRegion,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferImageCopy *copyParams,
-	Refresh_TransferOptions transferOption
-) {
-	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
-	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) commandBuffer;
-	VulkanTextureSlice *vulkanTextureSlice;
-	VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer*) transferBuffer;
-	VkBufferImageCopy imageCopy;
-
-	vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
-
-	if (
-		transferOption == REFRESH_TRANSFEROPTIONS_SAFEDISCARD &&
-		SDL_AtomicGet(&transferBufferContainer->activeBufferHandle->vulkanBuffer->referenceCount) > 0
-	) {
-		VULKAN_INTERNAL_DiscardActiveBuffer(
-			renderer,
-			transferBufferContainer
-		);
-		vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
-	}
-
-	VULKAN_INTERNAL_BufferMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_WRITE,
-		transferBufferContainer->activeBufferHandle->vulkanBuffer
-	);
-
-	VULKAN_INTERNAL_ImageMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_READ,
-		vulkanTextureSlice
-	);
-
-	imageCopy.imageExtent.width = textureRegion->w;
-	imageCopy.imageExtent.height = textureRegion->h;
-	imageCopy.imageExtent.depth = textureRegion->d;
-	imageCopy.imageOffset.x = textureRegion->x;
-	imageCopy.imageOffset.y = textureRegion->y;
-	imageCopy.imageOffset.z = textureRegion->z;
-	imageCopy.imageSubresource.aspectMask = vulkanTextureSlice->parent->aspectFlags;
-	imageCopy.imageSubresource.baseArrayLayer = textureRegion->textureSlice.layer;
-	imageCopy.imageSubresource.layerCount = 1;
-	imageCopy.imageSubresource.mipLevel = textureRegion->textureSlice.mipLevel;
-	imageCopy.bufferOffset = copyParams->bufferOffset;
-	imageCopy.bufferRowLength = copyParams->bufferStride;
-	imageCopy.bufferImageHeight = copyParams->bufferImageHeight;
-
-	renderer->vkCmdCopyImageToBuffer(
-		vulkanCommandBuffer->commandBuffer,
-		vulkanTextureSlice->parent->image,
-		AccessMap[vulkanTextureSlice->resourceAccessType].imageLayout,
-		transferBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
-		1,
-		&imageCopy
-	);
-
-	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, transferBufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-	VULKAN_INTERNAL_TrackCopiedTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-}
-
-static void VULKAN_DownloadFromBuffer(
-	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_GpuBuffer *gpuBuffer,
-	Refresh_TransferBuffer *transferBuffer,
-	Refresh_BufferCopy *copyParams,
-	Refresh_TransferOptions transferOption
-) {
-	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
-	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) commandBuffer;
-	VulkanBufferContainer *gpuBufferContainer = (VulkanBufferContainer*) gpuBuffer;
-	VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer*) transferBuffer;
-	VkBufferCopy bufferCopy;
-
-	if (
-		transferOption == REFRESH_TRANSFEROPTIONS_SAFEDISCARD &&
-		SDL_AtomicGet(&transferBufferContainer->activeBufferHandle->vulkanBuffer->referenceCount) > 0
-	) {
-		VULKAN_INTERNAL_DiscardActiveBuffer(
-			renderer,
-			transferBufferContainer
-		);
-	}
-
-	VULKAN_INTERNAL_BufferMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_WRITE,
-		transferBufferContainer->activeBufferHandle->vulkanBuffer
-	);
-
-	VULKAN_INTERNAL_BufferMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_READ,
-		gpuBufferContainer->activeBufferHandle->vulkanBuffer
-	);
-
-	bufferCopy.srcOffset = copyParams->srcOffset;
-	bufferCopy.dstOffset = copyParams->dstOffset;
-	bufferCopy.size = copyParams->size;
-
-	renderer->vkCmdCopyBuffer(
-		vulkanCommandBuffer->commandBuffer,
-		gpuBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
-		transferBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
-		1,
-		&bufferCopy
-	);
-
-	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, transferBufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, gpuBufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackCopiedBuffer(renderer, vulkanCommandBuffer, gpuBufferContainer->activeBufferHandle->vulkanBuffer);
-}
-
 static void VULKAN_CopyTextureToTexture(
 	Refresh_Renderer *driverData,
 	Refresh_CommandBuffer *commandBuffer,
@@ -8751,147 +8627,6 @@ static void VULKAN_CopyTextureToTexture(
 	VULKAN_INTERNAL_TrackCopiedTextureSlice(renderer, vulkanCommandBuffer, dstSlice);
 }
 
-static void VULKAN_CopyTextureToBuffer(
-	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_TextureRegion *textureRegion,
-	Refresh_GpuBuffer *gpuBuffer,
-	Refresh_BufferImageCopy *copyParams,
-	Refresh_WriteOptions writeOption
-) {
-	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
-	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) commandBuffer;
-	VulkanTextureSlice *vulkanTextureSlice;
-	VulkanBufferContainer *bufferContainer = (VulkanBufferContainer*) gpuBuffer;
-	VkBufferImageCopy imageCopy;
-
-	vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
-
-	if (
-		writeOption == REFRESH_WRITEOPTIONS_SAFEDISCARD &&
-		SDL_AtomicGet(&bufferContainer->activeBufferHandle->vulkanBuffer->referenceCount) > 0
-	) {
-		VULKAN_INTERNAL_DiscardActiveBuffer(
-			renderer,
-			bufferContainer
-		);
-	}
-
-	VULKAN_INTERNAL_ImageMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_READ,
-		vulkanTextureSlice
-	);
-
-	VULKAN_INTERNAL_BufferMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_WRITE,
-		bufferContainer->activeBufferHandle->vulkanBuffer
-	);
-
-	imageCopy.imageExtent.width = textureRegion->w;
-	imageCopy.imageExtent.height = textureRegion->h;
-	imageCopy.imageExtent.depth = textureRegion->d;
-	imageCopy.imageOffset.x = textureRegion->x;
-	imageCopy.imageOffset.y = textureRegion->y;
-	imageCopy.imageOffset.z = textureRegion->z;
-	imageCopy.imageSubresource.aspectMask = vulkanTextureSlice->parent->aspectFlags;
-	imageCopy.imageSubresource.baseArrayLayer = textureRegion->textureSlice.layer;
-	imageCopy.imageSubresource.layerCount = 1;
-	imageCopy.imageSubresource.mipLevel = textureRegion->textureSlice.mipLevel;
-	imageCopy.bufferOffset = copyParams->bufferOffset;
-	imageCopy.bufferRowLength = copyParams->bufferStride;
-	imageCopy.bufferImageHeight = copyParams->bufferImageHeight;
-
-	renderer->vkCmdCopyImageToBuffer(
-		vulkanCommandBuffer->commandBuffer,
-		vulkanTextureSlice->parent->image,
-		AccessMap[vulkanTextureSlice->resourceAccessType].imageLayout,
-		bufferContainer->activeBufferHandle->vulkanBuffer->buffer,
-		1,
-		&imageCopy
-	);
-
-	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, bufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-	VULKAN_INTERNAL_TrackCopiedBuffer(renderer, vulkanCommandBuffer, bufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackCopiedTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-}
-
-static void VULKAN_CopyBufferToTexture(
-	Refresh_Renderer *driverData,
-	Refresh_CommandBuffer *commandBuffer,
-	Refresh_GpuBuffer *gpuBuffer,
-	Refresh_TextureRegion *textureRegion,
-	Refresh_BufferImageCopy *copyParams,
-	Refresh_WriteOptions writeOption
-) {
-	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
-	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) commandBuffer;
-	VulkanBufferContainer *bufferContainer = (VulkanBufferContainer*) gpuBuffer;
-	VulkanTextureContainer *textureContainer = (VulkanTextureContainer*) textureRegion->textureSlice.texture;
-	VulkanTextureSlice *vulkanTextureSlice;
-	VkBufferImageCopy imageCopy;
-
-	vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
-
-	if (
-		writeOption == REFRESH_WRITEOPTIONS_SAFEDISCARD &&
-		textureContainer->canBeDiscarded &&
-		SDL_AtomicGet(&vulkanTextureSlice->referenceCount) > 0
-	) {
-		VULKAN_INTERNAL_DiscardActiveTexture(
-			renderer,
-			textureContainer
-		);
-		vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
-	}
-
-	VULKAN_INTERNAL_BufferMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_READ,
-		bufferContainer->activeBufferHandle->vulkanBuffer
-	);
-
-	VULKAN_INTERNAL_ImageMemoryBarrier(
-		renderer,
-		vulkanCommandBuffer->commandBuffer,
-		RESOURCE_ACCESS_TRANSFER_WRITE,
-		vulkanTextureSlice
-	);
-
-	imageCopy.imageExtent.width = textureRegion->w;
-	imageCopy.imageExtent.height = textureRegion->h;
-	imageCopy.imageExtent.depth = textureRegion->d;
-	imageCopy.imageOffset.x = textureRegion->x;
-	imageCopy.imageOffset.y = textureRegion->y;
-	imageCopy.imageOffset.z = textureRegion->z;
-	imageCopy.imageSubresource.aspectMask = vulkanTextureSlice->parent->aspectFlags;
-	imageCopy.imageSubresource.baseArrayLayer = textureRegion->textureSlice.layer;
-	imageCopy.imageSubresource.layerCount = 1;
-	imageCopy.imageSubresource.mipLevel = textureRegion->textureSlice.mipLevel;
-	imageCopy.bufferOffset = copyParams->bufferOffset;
-	imageCopy.bufferRowLength = copyParams->bufferStride;
-	imageCopy.bufferImageHeight = copyParams->bufferImageHeight;
-
-	renderer->vkCmdCopyBufferToImage(
-		vulkanCommandBuffer->commandBuffer,
-		bufferContainer->activeBufferHandle->vulkanBuffer->buffer,
-		vulkanTextureSlice->parent->image,
-		AccessMap[vulkanTextureSlice->resourceAccessType].imageLayout,
-		1,
-		&imageCopy
-	);
-
-	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, bufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-	VULKAN_INTERNAL_TrackCopiedBuffer(renderer, vulkanCommandBuffer, bufferContainer->activeBufferHandle->vulkanBuffer);
-	VULKAN_INTERNAL_TrackCopiedTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
-}
-
 static void VULKAN_CopyBufferToBuffer(
 	Refresh_Renderer *driverData,
 	Refresh_CommandBuffer *commandBuffer,
@@ -10461,6 +10196,137 @@ static void VULKAN_ReleaseFence(
 	VULKAN_INTERNAL_ReturnFenceToPool((VulkanRenderer*) driverData, (VkFence) fence);
 }
 
+/* Readback */
+
+static void VULKAN_DownloadFromTexture(
+	Refresh_Renderer *driverData,
+	Refresh_TextureRegion *textureRegion,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferImageCopy *copyParams,
+	Refresh_TransferOptions transferOption
+) {
+	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
+	VulkanTextureSlice *vulkanTextureSlice;
+	VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer*) transferBuffer;
+	VkBufferImageCopy imageCopy;
+	vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
+	Refresh_Fence *fence;
+	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) VULKAN_AcquireCommandBuffer(driverData);
+
+	if (
+		transferOption == REFRESH_TRANSFEROPTIONS_SAFEDISCARD &&
+		SDL_AtomicGet(&transferBufferContainer->activeBufferHandle->vulkanBuffer->referenceCount) > 0
+	) {
+		VULKAN_INTERNAL_DiscardActiveBuffer(
+			renderer,
+			transferBufferContainer
+		);
+		vulkanTextureSlice = VULKAN_INTERNAL_RefreshToVulkanTextureSlice(&textureRegion->textureSlice);
+	}
+
+	VULKAN_INTERNAL_BufferMemoryBarrier(
+		renderer,
+		vulkanCommandBuffer->commandBuffer,
+		RESOURCE_ACCESS_TRANSFER_WRITE,
+		transferBufferContainer->activeBufferHandle->vulkanBuffer
+	);
+
+	VULKAN_INTERNAL_ImageMemoryBarrier(
+		renderer,
+		vulkanCommandBuffer->commandBuffer,
+		RESOURCE_ACCESS_TRANSFER_READ,
+		vulkanTextureSlice
+	);
+
+	imageCopy.imageExtent.width = textureRegion->w;
+	imageCopy.imageExtent.height = textureRegion->h;
+	imageCopy.imageExtent.depth = textureRegion->d;
+	imageCopy.imageOffset.x = textureRegion->x;
+	imageCopy.imageOffset.y = textureRegion->y;
+	imageCopy.imageOffset.z = textureRegion->z;
+	imageCopy.imageSubresource.aspectMask = vulkanTextureSlice->parent->aspectFlags;
+	imageCopy.imageSubresource.baseArrayLayer = textureRegion->textureSlice.layer;
+	imageCopy.imageSubresource.layerCount = 1;
+	imageCopy.imageSubresource.mipLevel = textureRegion->textureSlice.mipLevel;
+	imageCopy.bufferOffset = copyParams->bufferOffset;
+	imageCopy.bufferRowLength = copyParams->bufferStride;
+	imageCopy.bufferImageHeight = copyParams->bufferImageHeight;
+
+	renderer->vkCmdCopyImageToBuffer(
+		vulkanCommandBuffer->commandBuffer,
+		vulkanTextureSlice->parent->image,
+		AccessMap[vulkanTextureSlice->resourceAccessType].imageLayout,
+		transferBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
+		1,
+		&imageCopy
+	);
+
+	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, transferBufferContainer->activeBufferHandle->vulkanBuffer);
+	VULKAN_INTERNAL_TrackTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
+	VULKAN_INTERNAL_TrackCopiedTextureSlice(renderer, vulkanCommandBuffer, vulkanTextureSlice);
+
+	fence = VULKAN_SubmitAndAcquireFence(driverData, (Refresh_CommandBuffer*) vulkanCommandBuffer);
+	VULKAN_WaitForFences(driverData, 1, 1, &fence);
+}
+
+static void VULKAN_DownloadFromBuffer(
+	Refresh_Renderer *driverData,
+	Refresh_GpuBuffer *gpuBuffer,
+	Refresh_TransferBuffer *transferBuffer,
+	Refresh_BufferCopy *copyParams,
+	Refresh_TransferOptions transferOption
+) {
+	VulkanRenderer *renderer = (VulkanRenderer*) driverData;
+	VulkanBufferContainer *gpuBufferContainer = (VulkanBufferContainer*) gpuBuffer;
+	VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer*) transferBuffer;
+	VkBufferCopy bufferCopy;
+	Refresh_Fence *fence;
+	VulkanCommandBuffer *vulkanCommandBuffer = (VulkanCommandBuffer*) VULKAN_AcquireCommandBuffer(driverData);
+
+	if (
+		transferOption == REFRESH_TRANSFEROPTIONS_SAFEDISCARD &&
+		SDL_AtomicGet(&transferBufferContainer->activeBufferHandle->vulkanBuffer->referenceCount) > 0
+	) {
+		VULKAN_INTERNAL_DiscardActiveBuffer(
+			renderer,
+			transferBufferContainer
+		);
+	}
+
+	VULKAN_INTERNAL_BufferMemoryBarrier(
+		renderer,
+		vulkanCommandBuffer->commandBuffer,
+		RESOURCE_ACCESS_TRANSFER_WRITE,
+		transferBufferContainer->activeBufferHandle->vulkanBuffer
+	);
+
+	VULKAN_INTERNAL_BufferMemoryBarrier(
+		renderer,
+		vulkanCommandBuffer->commandBuffer,
+		RESOURCE_ACCESS_TRANSFER_READ,
+		gpuBufferContainer->activeBufferHandle->vulkanBuffer
+	);
+
+	bufferCopy.srcOffset = copyParams->srcOffset;
+	bufferCopy.dstOffset = copyParams->dstOffset;
+	bufferCopy.size = copyParams->size;
+
+	renderer->vkCmdCopyBuffer(
+		vulkanCommandBuffer->commandBuffer,
+		gpuBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
+		transferBufferContainer->activeBufferHandle->vulkanBuffer->buffer,
+		1,
+		&bufferCopy
+	);
+
+	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, transferBufferContainer->activeBufferHandle->vulkanBuffer);
+	VULKAN_INTERNAL_TrackBuffer(renderer, vulkanCommandBuffer, gpuBufferContainer->activeBufferHandle->vulkanBuffer);
+	VULKAN_INTERNAL_TrackCopiedBuffer(renderer, vulkanCommandBuffer, gpuBufferContainer->activeBufferHandle->vulkanBuffer);
+
+	fence = VULKAN_SubmitAndAcquireFence(driverData, (Refresh_CommandBuffer*) vulkanCommandBuffer);
+	VULKAN_WaitForFences(driverData, 1, 1, &fence);
+}
+
 /* Device instantiation */
 
 static inline uint8_t CheckDeviceExtensions(