[hdSt, hgiVulkan] Vulkan validation error fixes for AMD.

Fixed bugs around HgiVulkan access masks for layout transition barriers and
provided correct read usage flags for depth buffers in Vulkan.

Contribution: Vipul Kapoor

(Internal change: 2330922)

pxr/imaging/hdSt/renderBuffer.cpp

@@ -20,16 +20,18 @@ PXR_NAMESPACE_OPEN_SCOPE
 static 
 HgiTextureUsage _GetTextureUsage(HdFormat format, TfToken const &name)
 {
+    // We are assuming at some point in a render buffer's lifetime it could be
+    // used to read from, so provide that ability to the render buffer. This is 
+    // especially useful for the HgiVulkan backend.
+
     if (HdAovHasDepthSemantic(name)) {
-        return HgiTextureUsageBitsDepthTarget;
+        return HgiTextureUsageBitsDepthTarget | HgiTextureUsageBitsShaderRead;
     } else if (HdAovHasDepthStencilSemantic(name)) {
         return HgiTextureUsageBitsDepthTarget |
-               HgiTextureUsageBitsStencilTarget;
+               HgiTextureUsageBitsStencilTarget |
+               HgiTextureUsageBitsShaderRead;
     }
 
-    // We are assuming at some point in a render buffer's lifetime it could be
-    // used to read from, so provide that ability to the render buffer. This is 
-    // especially useful when for the HgiVulkan back-end.
     return HgiTextureUsageBitsColorTarget | HgiTextureUsageBitsShaderRead;
 }
 

pxr/imaging/hgiVulkan/texture.cpp

@@ -619,18 +619,15 @@ HgiVulkanTexture::GetDefaultImageLayout(HgiTextureUsage usage)
     if (usage & HgiTextureUsageBitsShaderWrite) {
         // Assume the ShaderWrite means its a storage image.
         return VK_IMAGE_LAYOUT_GENERAL;
-    } else if (usage & HgiTextureUsageBitsShaderRead) {
-        // Also check if image is going to be used as a color attachment as 
-        // well. If yes, then explicitly give it a color attachment layout.
-        if (usage & HgiTextureUsageBitsColorTarget) {
-            return VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
-        } else {
-            return VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
-        }
-    } else if (usage & HgiTextureUsageBitsDepthTarget) {
-        return VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
+    // Prioritize attachment layouts over shader read layout. Some textures 
+    // might have both usages.
     } else if (usage & HgiTextureUsageBitsColorTarget) {
         return VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+    } else if (usage & HgiTextureUsageBitsDepthTarget ||
+               usage & HgiTextureUsageBitsStencilTarget) {
+        return VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
+    } else if (usage & HgiTextureUsageBitsShaderRead) {
+        return VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
     }
 
     return VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;