[HDRP] Fix flickering / edge aliasing issue when DoF and TAAU or DLSS are enabled (#6371)

* Fix flickering / edge aliasing issue when DoF and TAAU or DLSS are enabled

* Cache and reuse scaled texture coord

* Update CHANGELOG.md

Co-authored-by: JulienIgnace-Unity <julien@unity3d.com>

Author: pmavridis

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

@@ -33,6 +33,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed missing information in the tooltip of affects smooth surfaces of the ray traced reflections denoiser (case 1376918).
 - Fixed broken debug views when dynamic resolution was enabled (case 1365368).
 - Fixed shader graph errors when disabling the bias on texture samplers.
+- Fixed flickering / edge aliasing issue when DoF and TAAU or DLSS are enabled (case 1381858).
 
 ### Changed
 - Optimizations for the physically based depth of field.

com.unity.render-pipelines.high-definition/Runtime/PostProcessing/Shaders/DepthOfFieldCoCReproject.compute

@@ -54,10 +54,11 @@ void KMain(uint3 dispatchThreadId : SV_DispatchThreadID)
     float coc3 = cocBR.x;
     float coc4 = cocBR.z;
 #else
-    float coc1 = LOAD_TEXTURE2D_X(_InputCoCTexture, posInputs.positionSS - uint2(1u, 0u)).x; // Left
-    float coc2 = LOAD_TEXTURE2D_X(_InputCoCTexture, posInputs.positionSS - uint2(0u, 1u)).x; // Top
-    float coc3 = LOAD_TEXTURE2D_X(_InputCoCTexture, posInputs.positionSS + uint2(0u, 1u)).x; // Bottom
-    float coc4 = LOAD_TEXTURE2D_X(_InputCoCTexture, posInputs.positionSS + uint2(1u, 0u)).x; // Right
+    float2 coord = ClampAndScaleUVPostProcessTextureForPoint(posInputs.positionSS);
+    float coc1 = LOAD_TEXTURE2D_X(_InputCoCTexture, coord - uint2(1u, 0u)).x; // Left
+    float coc2 = LOAD_TEXTURE2D_X(_InputCoCTexture, coord - uint2(0u, 1u)).x; // Top
+    float coc3 = LOAD_TEXTURE2D_X(_InputCoCTexture, coord + uint2(0u, 1u)).x; // Bottom
+    float coc4 = LOAD_TEXTURE2D_X(_InputCoCTexture, coord + uint2(1u, 0u)).x; // Right
 #endif
 
     // Dejittered center sample

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.PostProcess.cs

@@ -2884,9 +2884,13 @@ TextureHandle DepthOfFieldPass(RenderGraph renderGraph, HDCamera hdCamera, Textu
         {
             bool postDoFTAAEnabled = false;
             bool isSceneView = hdCamera.camera.cameraType == CameraType.SceneView;
-            bool taaEnabled = m_AntialiasingFS && hdCamera.antialiasing == HDAdditionalCameraData.AntialiasingMode.TemporalAntialiasing;
+            bool stabilizeCoC = m_AntialiasingFS && hdCamera.antialiasing == HDAdditionalCameraData.AntialiasingMode.TemporalAntialiasing;
             bool isOrtho = hdCamera.camera.orthographic;
 
+            // If DLSS is enabled, we need to stabilize the CoC buffer (because the upsampled depth is jittered)
+            if (m_DLSSPassEnabled)
+                stabilizeCoC = true;
+
             // If Path tracing is enabled, then DoF is computed in the path tracer by sampling the lens aperure (when using the physical camera mode)
             bool isDoFPathTraced = (hdCamera.frameSettings.IsEnabled(FrameSettingsField.RayTracing) &&
                 hdCamera.volumeStack.GetComponent<PathTracing>().enable.value &&
@@ -2899,7 +2903,7 @@ TextureHandle DepthOfFieldPass(RenderGraph renderGraph, HDCamera hdCamera, Textu
             {
                 // If we switch DoF modes and the old one was not using TAA, make sure we invalidate the history
                 // Note: for Rendergraph the m_IsDoFHisotoryValid perhaps should be moved to the "pass data" struct
-                if (taaEnabled && hdCamera.dofHistoryIsValid != m_DepthOfField.physicallyBased)
+                if (stabilizeCoC && hdCamera.dofHistoryIsValid != m_DepthOfField.physicallyBased)
                 {
                     hdCamera.resetPostProcessingHistory = true;
                 }
@@ -2928,7 +2932,7 @@ TextureHandle DepthOfFieldPass(RenderGraph renderGraph, HDCamera hdCamera, Textu
                     TextureHandle dest = GetPostprocessOutputHandle(renderGraph, "DoF Destination");
                     passData.destination = builder.WriteTexture(dest);
                     passData.motionVecTexture = builder.ReadTexture(motionVectors);
-                    passData.taaEnabled = taaEnabled;
+                    passData.taaEnabled = stabilizeCoC;
 
                     if (!m_DepthOfField.physicallyBased)
                     {
@@ -3079,7 +3083,7 @@ TextureHandle DepthOfFieldPass(RenderGraph renderGraph, HDCamera hdCamera, Textu
                 }
 
                 // When physically based DoF is enabled, TAA runs two times, first to stabilize the color buffer before DoF and then after DoF to accumulate more aperture samples
-                if (taaEnabled && m_DepthOfField.physicallyBased)
+                if (stabilizeCoC && m_DepthOfField.physicallyBased)
                 {
                     source = DoTemporalAntialiasing(renderGraph, hdCamera, depthBuffer, motionVectors, depthBufferMipChain, source, stencilTexture, postDoF: true, "Post-DoF TAA Destination");
                     hdCamera.dofHistoryIsValid = true;