Vulkan: Add RenderTargetVk::getImageForRead.

src/libANGLE/renderer/vulkan/FramebufferVk.cpp

@@ -110,7 +110,6 @@ gl::Error FramebufferVk::clear(const gl::Context *context, GLbitfield mask)
 {
     ContextVk *contextVk = vk::GetImpl(context);
     RendererVk *renderer = contextVk->getRenderer();
-    Serial currentSerial = renderer->getCurrentQueueSerial();
 
     // This command buffer is only started once.
     vk::CommandBuffer *commandBuffer = nullptr;
@@ -180,7 +179,7 @@ gl::Error FramebufferVk::clear(const gl::Context *context, GLbitfield mask)
         const angle::Format &format          = renderTarget->getImageFormat().textureFormat();
         const VkImageAspectFlags aspectFlags = vk::GetDepthStencilAspectFlags(format);
 
-        vk::ImageHelper *image       = renderTarget->getImageForWrite(currentSerial, this);
+        vk::ImageHelper *image = renderTarget->getImageForWrite(this);
         image->clearDepthStencil(aspectFlags, clearDepthStencilValue, commandBuffer);
     }
 
@@ -214,7 +213,7 @@ gl::Error FramebufferVk::clear(const gl::Context *context, GLbitfield mask)
         }
 
         ASSERT(colorRenderTarget);
-        vk::ImageHelper *image = colorRenderTarget->getImageForWrite(currentSerial, this);
+        vk::ImageHelper *image = colorRenderTarget->getImageForWrite(this);
         GLint mipLevelToClear  = (attachment->type() == GL_TEXTURE) ? attachment->mipLevel() : 0;
         image->clearColor(modifiedClearColorValue, mipLevelToClear, 1, commandBuffer);
     }
@@ -797,9 +796,8 @@ gl::Error FramebufferVk::readPixelsImpl(const gl::Context *context,
     RenderTargetVk *renderTarget = getColorReadRenderTarget();
 
     // Note that although we're reading from the image, we need to update the layout below.
-    // TODO(jmadill): Clearify read/write semantics. http://anglebug.com/2539
-    vk::ImageHelper *srcImage =
-        renderTarget->getImageForWrite(renderer->getCurrentQueueSerial(), this);
+    vk::ImageHelper *srcImage = renderTarget->getImageForRead(
+        this, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, VK_IMAGE_ASPECT_COLOR_BIT, commandBuffer);
 
     const angle::Format &angleFormat = srcImage->getFormat().textureFormat();
     VkBuffer bufferHandle            = VK_NULL_HANDLE;
@@ -826,10 +824,6 @@ gl::Error FramebufferVk::readPixelsImpl(const gl::Context *context,
     region.imageSubresource.layerCount     = 1;
     region.imageSubresource.mipLevel       = 0;
 
-    srcImage->changeLayoutWithStages(
-        VK_IMAGE_ASPECT_COLOR_BIT, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
-        VK_PIPELINE_STAGE_ALL_COMMANDS_BIT, VK_PIPELINE_STAGE_ALL_COMMANDS_BIT, commandBuffer);
-
     commandBuffer->copyImageToBuffer(srcImage->getImage(), srcImage->getCurrentLayout(),
                                      bufferHandle, 1, &region);
 

src/libANGLE/renderer/vulkan/RenderTargetVk.cpp

@@ -104,8 +104,23 @@ void RenderTargetVk::updateSwapchainImage(vk::ImageHelper *image, vk::ImageView
     mImageView = imageView;
 }
 
-vk::ImageHelper *RenderTargetVk::getImageForWrite(Serial currentSerial,
-                                                  vk::CommandGraphResource *writingResource) const
+vk::ImageHelper *RenderTargetVk::getImageForRead(vk::CommandGraphResource *readingResource,
+                                                 VkImageLayout layout,
+                                                 VkImageAspectFlags aspectFlags,
+                                                 vk::CommandBuffer *commandBuffer)
+{
+    ASSERT(mImage && mImage->valid());
+
+    // TODO(jmadill): Better simultaneous resource access. http://anglebug.com/2679
+    mResource->addWriteDependency(readingResource);
+
+    mImage->changeLayoutWithStages(aspectFlags, layout, VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
+                                   VK_PIPELINE_STAGE_ALL_COMMANDS_BIT, commandBuffer);
+
+    return mImage;
+}
+
+vk::ImageHelper *RenderTargetVk::getImageForWrite(vk::CommandGraphResource *writingResource) const
 {
     ASSERT(mImage && mImage->valid());
     mResource->addWriteDependency(writingResource);

src/libANGLE/renderer/vulkan/RenderTargetVk.h

@@ -48,8 +48,12 @@ class RenderTargetVk final : public FramebufferAttachmentRenderTarget
 
     const vk::ImageHelper &getImage() const;
 
-    vk::ImageHelper *getImageForWrite(Serial currentSerial,
-                                      vk::CommandGraphResource *writingResource) const;
+    // getImageForRead will also transition the resource to the given layout.
+    vk::ImageHelper *getImageForRead(vk::CommandGraphResource *readingResource,
+                                     VkImageLayout layout,
+                                     VkImageAspectFlags aspectFlags,
+                                     vk::CommandBuffer *commandBuffer);
+    vk::ImageHelper *getImageForWrite(vk::CommandGraphResource *writingResource) const;
     vk::ImageView *getImageView() const;
     vk::CommandGraphResource *getResource() const;