Only ignore transitions from undefined current state for partial updates

* If the current state of a temporary ImageState is unknown in a renderpass
  transition mid-command buffer that means it's a subresource which isn't
  touched and we want to skip barriering it. We *don't* want to barrier from
  UNDEFINED and discard.
* However if this is a real ImageState which hasn't been initialised, we do want
  to do that. So only opt-in to the skipping behaviour in the case we know this
  isn't a 'real' ImageState but a temporary tracker.

renderdoc/driver/vulkan/vk_image_states.cpp

@@ -1271,8 +1271,9 @@ void ImageState::Transition(const ImageState &dstState, VkAccessFlags srcAccessM
     {
       ImageSubresourceState srcSub;
 
-      // ignore transitions of subresources that were untouched
-      if(it->state() == ImageSubresourceState())
+      // ignore transitions of subresources that were untouched if this isn't the *canonical* image
+      // state, but just an overlay tracking changes within a command buffer
+      if(it->state() == ImageSubresourceState() && m_Overlay)
         continue;
 
       if(!it->state().Update(dstSub, srcSub, info.GetFrameRefCompFunc()))

renderdoc/driver/vulkan/vk_resources.h

@@ -1700,6 +1700,7 @@ struct ImageState
   rdcarray<VkImageMemoryBarrier> oldQueueFamilyTransfers;
   rdcarray<VkImageMemoryBarrier> newQueueFamilyTransfers;
   bool isMemoryBound = false;
+  bool m_Overlay = false;
   ResourceId boundMemory = ResourceId();
   VkDeviceSize boundMemoryOffset = 0ull;
   VkDeviceSize boundMemorySize = 0ull;
@@ -1712,6 +1713,7 @@ struct ImageState
       : wrappedHandle(wrappedHandle), subresourceStates(imageInfo, refType), maxRefType(refType)
   {
   }
+  void SetOverlay() { m_Overlay = true; }
   ImageState InitialState() const;
   void InitialState(ImageState &result) const;
   ImageState CommandBufferInitialState() const;

renderdoc/driver/vulkan/wrappers/vk_cmd_funcs.cpp

@@ -1164,6 +1164,7 @@ bool WrappedVulkan::Serialise_vkEndCommandBuffer(SerialiserType &ser, VkCommandB
           {
             ResourceId id = it->first;
             ImageState &endState = it->second;
+            endState.SetOverlay();
             LockedConstImageStateRef current = FindConstImageState(id);
             if(!current)
             {