Fix issues in the post process system with RenderTexture being invalid in some cases. Causing rendering problems. #6480

Author: JulienIgnace-Unity

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -503,6 +503,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed alpha clipping test (comparison was '>', now '>=')
 - Fixed preview camera (eg. shader graph preview) when path tracing is on
 - Fixed issue with unclear naming of debug menu for decals.
+- Fix issues in the post process system with RenderTexture being invalid in some cases, causing rendering problems.
 
 ### Changed
 - Color buffer pyramid is not allocated anymore if neither refraction nor distortion are enabled

com.unity.render-pipelines.high-definition/Runtime/PostProcessing/PostProcessSystem.cs

@@ -133,6 +133,15 @@ private enum SMAAStage
 
         HDRenderPipeline m_HDInstance;
 
+        void FillEmptyExposureTexture()
+        {
+            var tex = new Texture2D(1, 1, TextureFormat.RGHalf, false, true);
+            tex.SetPixel(0, 0, new Color(1f, ColorUtils.ConvertExposureToEV100(1f), 0f, 0f));
+            tex.Apply();
+            Graphics.Blit(tex, m_EmptyExposureTexture);
+            CoreUtils.Destroy(tex);
+        }
+
         public PostProcessSystem(HDRenderPipelineAsset hdAsset, RenderPipelineResources defaultResources)
         {
             m_Resources = defaultResources;
@@ -206,11 +215,7 @@ public PostProcessSystem(HDRenderPipelineAsset hdAsset, RenderPipelineResources
             // TODO: Write a version that uses structured buffer instead of texture to do atomic as Metal doesn't support atomics on textures.
             m_MotionBlurSupportsScattering = m_MotionBlurSupportsScattering && (SystemInfo.graphicsDeviceType != GraphicsDeviceType.Metal);
 
-            var tex = new Texture2D(1, 1, TextureFormat.RGHalf, false, true);
-            tex.SetPixel(0, 0, new Color(1f, ColorUtils.ConvertExposureToEV100(1f), 0f, 0f));
-            tex.Apply();
-            Graphics.Blit(tex, m_EmptyExposureTexture);
-            CoreUtils.Destroy(tex);
+            FillEmptyExposureTexture();
 
             // Initialize our target pool to ease RT management
             m_Pool = new TargetPool();
@@ -287,6 +292,23 @@ public void Cleanup()
             m_FarBokehTileList          = null;
         }
 
+        // In some cases, the internal buffer of render textures might be invalid.
+        // Usually when using these textures with API such as SetRenderTarget, they are recreated internally.
+        // This is not the case when these textures are used exclusively with Compute Shaders. So to make sure they work in this case, we recreate them here.
+        void CheckRenderTexturesValidity()
+        {
+            if (!m_EmptyExposureTexture.rt.IsCreated())
+                FillEmptyExposureTexture();
+
+            HDUtils.CheckRTCreated(m_InternalLogLut.rt);
+            HDUtils.CheckRTCreated(m_TempTexture1024.rt);
+            HDUtils.CheckRTCreated(m_TempTexture32.rt);
+            if (m_KeepAlpha)
+            {
+                HDUtils.CheckRTCreated(m_AlphaTexture.rt);
+            }
+        }
+
         public void BeginFrame(CommandBuffer cmd, HDCamera camera, HDRenderPipeline hdInstance)
         {
             m_HDInstance = hdInstance;
@@ -336,6 +358,8 @@ public void BeginFrame(CommandBuffer cmd, HDCamera camera, HDRenderPipeline hdIn
             m_DitheringFS           = frameSettings.IsEnabled(FrameSettingsField.Dithering);
             m_AntialiasingFS        = frameSettings.IsEnabled(FrameSettingsField.Antialiasing);
 
+            CheckRenderTexturesValidity();
+
             // Handle fixed exposure & disabled pre-exposure by forcing an exposure multiplier of 1
             if (!m_ExposureControlFS)
             {
@@ -2644,7 +2668,11 @@ public RTHandle Get(in Vector2 scaleFactor, GraphicsFormat format, bool mipmap =
                 var hashCode = ComputeHashCode(scaleFactor.x, scaleFactor.y, (int)format, mipmap);
 
                 if (m_Targets.TryGetValue(hashCode, out var stack) && stack.Count > 0)
-                    return stack.Pop();
+                {
+                    var tex = stack.Pop();
+                    HDUtils.CheckRTCreated(tex.rt);
+                    return tex;
+                }
 
                 var rt = RTHandles.Alloc(
                     scaleFactor, TextureXR.slices, DepthBits.None, colorFormat: format, dimension: TextureXR.dimension,