(PR #5) ColorGradingLutPass should have its color attachment set to the LUT render target.

Otherwise, the color pass ends up enabling XR mode.

Author: Kleptine

com.unity.render-pipelines.universal/Runtime/2D/Renderer2D.cs

@@ -164,7 +164,7 @@ public override void Setup(ScriptableRenderContext context, ref RenderingData re
             // We generate color LUT in the base camera only. This allows us to not break render pass execution for overlay cameras.
             if (stackHasPostProcess && cameraData.renderType == CameraRenderType.Base)
             {
-                m_ColorGradingLutPass.Setup(k_ColorGradingLutHandle);
+                m_ColorGradingLutPass.Setup(k_ColorGradingLutHandle, ref renderingData);
                 EnqueuePass(m_ColorGradingLutPass);
             }
 

com.unity.render-pipelines.universal/Runtime/Data/UniversalRenderPipelineAsset.cs

@@ -122,8 +122,6 @@ public enum ColorTransformation
         InForwardPass
     }
 
-    }
-
     public class UniversalRenderPipelineAsset : RenderPipelineAsset, ISerializationCallbackReceiver
     {
         Shader m_DefaultShader;

com.unity.render-pipelines.universal/Runtime/ForwardRenderer.cs

@@ -247,7 +247,7 @@ public override void Setup(ScriptableRenderContext context, ref RenderingData re
 
             if (generateColorGradingLUT)
             {
-                m_ColorGradingLutPass.Setup(m_ColorGradingLut);
+                m_ColorGradingLutPass.Setup(m_ColorGradingLut, ref renderingData);
                 EnqueuePass(m_ColorGradingLutPass);
             }
 

com.unity.render-pipelines.universal/Runtime/Passes/ColorGradingLutPass.cs

@@ -16,6 +16,7 @@ public class ColorGradingLutPass : ScriptableRenderPass
         readonly GraphicsFormat m_HdrLutFormat;
         readonly GraphicsFormat m_LdrLutFormat;
 
+        RenderTextureDescriptor lutTextureDescriptor;
         RenderTargetHandle m_InternalLut;
 
         public ColorGradingLutPass(RenderPassEvent evt, PostProcessData data)
@@ -53,9 +54,30 @@ Material Load(Shader shader)
             m_LdrLutFormat = GraphicsFormat.R8G8B8A8_UNorm;
         }
 
-        public void Setup(in RenderTargetHandle internalLut)
+        public void Setup(in RenderTargetHandle internalLut, ref RenderingData renderingData)
         {
             m_InternalLut = internalLut;
+
+            ref var postProcessingData = ref renderingData.postProcessingData;
+            bool hdr = postProcessingData.gradingMode == ColorGradingMode.HighDynamicRange;
+            int lutHeight = postProcessingData.lutSize;
+            int lutWidth = lutHeight * lutHeight;
+            var format = hdr ? m_HdrLutFormat : m_LdrLutFormat;
+
+            lutTextureDescriptor = new RenderTextureDescriptor(lutWidth, lutHeight, format, 0);
+            lutTextureDescriptor.vrUsage = VRTextureUsage.None; // We only need one for both eyes in VR
+        }
+
+        /// <inheritdoc />
+        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
+        {
+            // Create and set the render target to the LUT texture.
+            cmd.GetTemporaryRT(m_InternalLut.id, lutTextureDescriptor, FilterMode.Bilinear);
+
+            // (ASG) This is required, otherwise this pass has the default camera attachment, and the code in
+            // ScriptableRenderer.Execute enables XR mode for this pass (when in forward color grading mode).
+            // (John): I believe this is a bug in URP, and this should be set.
+            ConfigureTarget(m_InternalLut.Identifier());
         }
 
         /// <inheritdoc/>
@@ -80,11 +102,7 @@ public override void Execute(ScriptableRenderContext context, ref RenderingData
             // Prepare texture & material
             int lutHeight = postProcessingData.lutSize;
             int lutWidth = lutHeight * lutHeight;
-            var format = hdr ? m_HdrLutFormat : m_LdrLutFormat;
             var material = hdr ? m_LutBuilderHdr : m_LutBuilderLdr;
-            var desc = new RenderTextureDescriptor(lutWidth, lutHeight, format, 0);
-            desc.vrUsage = VRTextureUsage.None; // We only need one for both eyes in VR
-            cmd.GetTemporaryRT(m_InternalLut.id, desc, FilterMode.Bilinear);
 
             // Prepare data
             var lmsColorBalance = ColorUtils.ColorBalanceToLMSCoeffs(whiteBalance.temperature.value, whiteBalance.tint.value);