Exposed the volumetric clouds transmittance for volumetric clouds (case 1373283).

com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/HDRenderPipeline.VolumetricClouds.cs

@@ -624,13 +624,13 @@ void UpdateVolumetricClouds(HDCamera hdCamera, in VolumetricClouds settings)
             }
         }
 
-        void RenderVolumetricClouds(RenderGraph renderGraph, HDCamera hdCamera, TextureHandle colorBuffer, TextureHandle depthPyramid, TextureHandle motionVector, TextureHandle volumetricLighting, TextureHandle maxZMask)
+        TextureHandle RenderVolumetricClouds(RenderGraph renderGraph, HDCamera hdCamera, TextureHandle colorBuffer, TextureHandle depthPyramid, TextureHandle motionVector, TextureHandle volumetricLighting, TextureHandle maxZMask)
         {
             VolumetricClouds settings = hdCamera.volumeStack.GetComponent<VolumetricClouds>();
 
             // If the current volume does not enable the feature, quit right away.
             if (!HasVolumetricClouds(hdCamera, in settings))
-                return;
+                return renderGraph.defaultResources.whiteTextureXR;
 
             // Make sure the volumetric clouds are animated properly
             UpdateVolumetricClouds(hdCamera, in settings);
@@ -640,16 +640,20 @@ void RenderVolumetricClouds(RenderGraph renderGraph, HDCamera hdCamera, TextureH
             bool accumulationClouds = cameraType == TVolumetricCloudsCameraType.Default || cameraType == TVolumetricCloudsCameraType.PlanarReflection;
             bool fullResolutionClouds = cameraType == TVolumetricCloudsCameraType.BakedReflection;
 
+            TextureHandle result;
             if (accumulationClouds)
             {
-                RenderVolumetricClouds_Accumulation(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
+                result = RenderVolumetricClouds_Accumulation(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
                 // Make sure to mark the history frame index validity.
                 PropagateVolumetricCloudsHistoryValidity(hdCamera, settings.localClouds.value);
             }
             else if (fullResolutionClouds)
-                RenderVolumetricClouds_FullResolution(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
+                result = RenderVolumetricClouds_FullResolution(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
             else
-                RenderVolumetricClouds_LowResolution(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
+                result = RenderVolumetricClouds_LowResolution(renderGraph, hdCamera, cameraType, colorBuffer, depthPyramid, motionVector, volumetricLighting, maxZMask);
+
+            // Return the scattering and transmittance
+            return result;
         }
 
         void PreRenderVolumetricClouds(RenderGraph renderGraph, HDCamera hdCamera)

com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/HDRenderPipeline.VolumetricCloudsAccumulation.cs

@@ -344,7 +344,7 @@ class VolumetricCloudsAccumulationData
         TextureHandle RenderVolumetricClouds_Accumulation(RenderGraph renderGraph, HDCamera hdCamera, TVolumetricCloudsCameraType cameraType,
             TextureHandle colorBuffer, TextureHandle depthPyramid, TextureHandle motionVectors, TextureHandle volumetricLighting, TextureHandle maxZMask)
         {
-            using (var builder = renderGraph.AddRenderPass<VolumetricCloudsAccumulationData>("Generating the rays for RTR", out var passData, ProfilingSampler.Get(HDProfileId.VolumetricClouds)))
+            using (var builder = renderGraph.AddRenderPass<VolumetricCloudsAccumulationData>("Volumetric Clouds", out var passData, ProfilingSampler.Get(HDProfileId.VolumetricClouds)))
             {
                 builder.EnableAsyncCompute(false);
                 VolumetricClouds settings = hdCamera.volumeStack.GetComponent<VolumetricClouds>();
@@ -405,9 +405,12 @@ TextureHandle RenderVolumetricClouds_Accumulation(RenderGraph renderGraph, HDCam
                             data.intermediateColorBufferCopy, data.intermediateBufferUpscale);
                     });
 
+                // Push the texture to the debug menu
                 PushFullScreenDebugTexture(m_RenderGraph, passData.currentHistoryBuffer0, FullScreenDebugMode.VolumetricClouds);
 
-                return passData.colorBuffer;
+                // We return the volumetric clouds buffers rendered at half resolution. We should ideally return the full resolution transmittance, but
+                // this should be enough for the initial case (which is the lens flares). The transmittance can be found in the alpha channel.
+                return passData.currentHistoryBuffer0;
             }
         }
     }

com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/HDRenderPipeline.VolumetricCloudsFullResolution.cs

@@ -222,7 +222,8 @@ TextureHandle RenderVolumetricClouds_FullResolution(RenderGraph renderGraph, HDC
                             data.intermediateColorBufferCopy, data.intermediateBufferUpscale);
                     });
 
-                return passData.colorBuffer;
+                // In the case of reflection probes, we don't expect any pass that will need the transmittance mask of the clouds so we return white.
+                return renderGraph.defaultResources.whiteTextureXR;
             }
         }
     }

com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/HDRenderPipeline.VolumetricCloudsLowResolution.cs

@@ -283,7 +283,8 @@ TextureHandle RenderVolumetricClouds_LowResolution(RenderGraph renderGraph, HDCa
                             data.intermediateColorBufferCopy, data.intermediateBufferUpscale);
                     });
 
-                return passData.colorBuffer;
+                // In the case of reflection probes, we don't expect any pass that will need the transmittance mask of the clouds so we return white.
+                return renderGraph.defaultResources.whiteTextureXR;
             }
         }
     }

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

@@ -465,6 +465,7 @@ TextureHandle RenderPostProcess(RenderGraph renderGraph,
             TextureHandle backBuffer,
             TextureHandle uiBuffer,
             TextureHandle afterPostProcessBuffer,
+            TextureHandle sunOcclusionTexture,
             CullingResults cullResults,
             HDCamera hdCamera)
         {
@@ -551,7 +552,7 @@ TextureHandle RenderPostProcess(RenderGraph renderGraph,
                 // HDRP to reduce the amount of resolution lost at the center of the screen
                 source = PaniniProjectionPass(renderGraph, hdCamera, source);
 
-                source = LensFlareDataDrivenPass(renderGraph, hdCamera, source, depthBuffer);
+                source = LensFlareDataDrivenPass(renderGraph, hdCamera, source, depthBuffer, sunOcclusionTexture);
 
                 TextureHandle bloomTexture = BloomPass(renderGraph, hdCamera, source);
                 TextureHandle logLutOutput = ColorGradingPass(renderGraph);
@@ -3121,7 +3122,7 @@ void LensFlareMergeOcclusionDataDrivenPass(RenderGraph renderGraph, HDCamera hdC
             }
         }
 
-        TextureHandle LensFlareDataDrivenPass(RenderGraph renderGraph, HDCamera hdCamera, TextureHandle source, TextureHandle depthBuffer)
+        TextureHandle LensFlareDataDrivenPass(RenderGraph renderGraph, HDCamera hdCamera, TextureHandle source, TextureHandle depthBuffer, TextureHandle sunOcclusionTexture)
         {
             if (m_LensFlareDataDataDrivenFS && !LensFlareCommonSRP.Instance.IsEmpty())
             {

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

@@ -86,6 +86,7 @@ void RecordRenderGraph(RenderRequest renderRequest,
                 ShadowResult shadowResult = new ShadowResult();
                 BuildGPULightListOutput gpuLightListOutput = new BuildGPULightListOutput();
                 TextureHandle uiBuffer = m_RenderGraph.defaultResources.blackTextureXR;
+                TextureHandle sunOcclusionTexture = m_RenderGraph.defaultResources.whiteTexture;
 
                 if (m_CurrentDebugDisplaySettings.IsDebugDisplayEnabled() && m_CurrentDebugDisplaySettings.IsFullScreenDebugPassEnabled())
                 {
@@ -175,7 +176,7 @@ void RecordRenderGraph(RenderRequest renderRequest,
                     RenderSubsurfaceScattering(m_RenderGraph, hdCamera, colorBuffer, historyValidationTexture, ref lightingBuffers, ref prepassOutput);
 
                     RenderSky(m_RenderGraph, hdCamera, colorBuffer, volumetricLighting, prepassOutput.depthBuffer, msaa ? prepassOutput.depthAsColor : prepassOutput.depthPyramidTexture);
-                    RenderVolumetricClouds(m_RenderGraph, hdCamera, colorBuffer, prepassOutput.depthPyramidTexture, prepassOutput.motionVectorsBuffer, volumetricLighting, maxZMask);
+                    sunOcclusionTexture = RenderVolumetricClouds(m_RenderGraph, hdCamera, colorBuffer, prepassOutput.depthPyramidTexture, prepassOutput.motionVectorsBuffer, volumetricLighting, maxZMask);
 
                     // Send all the geometry graphics buffer to client systems if required (must be done after the pyramid and before the transparent depth pre-pass)
                     SendGeometryGraphicsBuffers(m_RenderGraph, prepassOutput.normalBuffer, prepassOutput.depthPyramidTexture, hdCamera);
@@ -263,7 +264,7 @@ void RecordRenderGraph(RenderRequest renderRequest,
 
 
                 TextureHandle afterPostProcessBuffer = RenderAfterPostProcessObjects(m_RenderGraph, hdCamera, cullingResults, prepassOutput);
-                TextureHandle postProcessDest = RenderPostProcess(m_RenderGraph, prepassOutput, colorBuffer, backBuffer, uiBuffer, afterPostProcessBuffer, cullingResults, hdCamera);
+                TextureHandle postProcessDest = RenderPostProcess(m_RenderGraph, prepassOutput, colorBuffer, backBuffer, uiBuffer, afterPostProcessBuffer, sunOcclusionTexture, cullingResults, hdCamera);
 
                 var xyMapping = GenerateDebugHDRxyMapping(m_RenderGraph, hdCamera, postProcessDest);
                 GenerateDebugImageHistogram(m_RenderGraph, hdCamera, postProcessDest);