[Vk] Keep MSAA vulkan texture in predictable state to avoid layout va…

…lidation errors when resolved texture of VulkanTextureGpuRenderTarget was used as shader resource. Can we skip this barrier if MSAA subtexture is already in required state?

RenderSystems/Vulkan/src/OgreVulkanRenderSystem.cpp

@@ -3292,20 +3292,28 @@ namespace Ogre
                 if( texture->isMultisample() && !texture->hasMsaaExplicitResolves() )
                 {
                     // Rare case where we render to an implicit resolve without resolving
-                    // (otherwise newLayout = ResolveDest)
-                    //
-                    // Or more common case if we need to copy to/from an MSAA texture
+                    // (otherwise newLayout = ResolveDest), or more common case if we need
+                    // to copy to/from an MSAA texture. We can also try to sample from texture.
+                    // In all these cases keep MSAA texture in predictable layout.
                     //
                     // This cannot catch all use cases, but if you fall into something this
                     // doesn't catch, then you should probably be using explicit resolves
-                    if( itor->newLayout == ResourceLayout::RenderTarget ||
-                        itor->newLayout == ResourceLayout::ResolveDest ||
-                        itor->newLayout == ResourceLayout::CopySrc ||
-                        itor->newLayout == ResourceLayout::CopyDst )
-                    {
-                        imageBarrier.image = texture->getMsaaFramebufferName();
-                        mImageBarriers.push_back( imageBarrier );
-                    }
+                    bool useNewLayoutForMsaa =
+                            itor->newLayout == ResourceLayout::RenderTarget ||
+                            itor->newLayout == ResourceLayout::ResolveDest ||
+                            itor->newLayout == ResourceLayout::CopySrc ||
+                            itor->newLayout == ResourceLayout::CopyDst;
+                    bool useOldLayoutForMsaa =
+                            itor->oldLayout == ResourceLayout::RenderTarget ||
+                            itor->oldLayout == ResourceLayout::ResolveDest ||
+                            itor->oldLayout == ResourceLayout::CopySrc ||
+                            itor->oldLayout == ResourceLayout::CopyDst;
+                    if( !useNewLayoutForMsaa )
+                        imageBarrier.newLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+                    if( !useOldLayoutForMsaa )
+                        imageBarrier.oldLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+                    imageBarrier.image = texture->getMsaaFramebufferName();
+                    mImageBarriers.push_back( imageBarrier );
                 }
             }
             else