Fixed the sub surface mask not being taken into account when computing ray traced sub surface scattering (1247255)

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

@@ -738,6 +738,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Improved performance of reflection probe management when using a lot of probes.
 - Ignoring the disable SSR flags for recursive rendering.
 - Removed logic in the UI to disable parameters for contact shadows and fog volume components as it was going against the concept of the volume system.
+- Fixed the sub surface mask not being taken into account when computing ray traced sub surface scattering.
 
 ## [7.1.1] - 2019-09-05
 

com.unity.render-pipelines.high-definition/Runtime/Material/SubsurfaceScattering/SubsurfaceScatteringManager.cs

@@ -288,10 +288,6 @@ void RenderSubsurfaceScattering(HDCamera hdCamera, CommandBuffer cmd, RTHandle c
                     int numTilesXHR = (hdCamera.actualWidth + (areaTileSize - 1)) / areaTileSize;
                     int numTilesYHR = (hdCamera.actualHeight + (areaTileSize - 1)) / areaTileSize;
 
-                    // Clear the integration texture first
-                    cmd.SetComputeTextureParam(m_ScreenSpaceShadowsCS, m_ClearShadowTexture, HDShaderIDs._RaytracedShadowIntegration, diffuseBufferRT);
-                    cmd.DispatchCompute(m_ScreenSpaceShadowsCS, m_ClearShadowTexture, numTilesXHR, numTilesYHR, hdCamera.viewCount);
-
                     // Fetch the volume overrides that we shall be using
                     RayTracingShader subSurfaceShader = m_Asset.renderPipelineRayTracingResources.subSurfaceRayTracing;
                     RayTracingSettings rayTracingSettings = hdCamera.volumeStack.GetComponent<RayTracingSettings>();
@@ -302,8 +298,13 @@ void RenderSubsurfaceScattering(HDCamera hdCamera, CommandBuffer cmd, RTHandle c
                     RTHandle intermediateBuffer1 = GetRayTracingBuffer(InternalRayTracingBuffers.RGBA1);
                     RTHandle intermediateBuffer2 = GetRayTracingBuffer(InternalRayTracingBuffers.RGBA2);
                     RTHandle intermediateBuffer3 = GetRayTracingBuffer(InternalRayTracingBuffers.RGBA3);
+                    RTHandle intermediateBuffer4 = GetRayTracingBuffer(InternalRayTracingBuffers.RGBA4);
                     RTHandle directionBuffer = GetRayTracingBuffer(InternalRayTracingBuffers.Direction);
 
+                    // Clear the integration texture first
+                    cmd.SetComputeTextureParam(m_ScreenSpaceShadowsCS, m_ClearShadowTexture, HDShaderIDs._RaytracedShadowIntegration, intermediateBuffer4);
+                    cmd.DispatchCompute(m_ScreenSpaceShadowsCS, m_ClearShadowTexture, numTilesXHR, numTilesYHR, hdCamera.viewCount);
+
                     // Grab the acceleration structure for the target camera
                     RayTracingAccelerationStructure accelerationStructure = RequestAccelerationStructure();
 
@@ -358,7 +359,7 @@ void RenderSubsurfaceScattering(HDCamera hdCamera, CommandBuffer cmd, RTHandle c
                         cmd.SetComputeTextureParam(deferredRayTracing, currentKernel, HDShaderIDs._DiffuseLightingTextureRW, intermediateBuffer3);
 
                         // Bind the output texture (it is used for accumulation read and write)
-                        cmd.SetComputeTextureParam(deferredRayTracing, currentKernel, HDShaderIDs._RaytracingLitBufferRW, diffuseBufferRT);
+                        cmd.SetComputeTextureParam(deferredRayTracing, currentKernel, HDShaderIDs._RaytracingLitBufferRW, intermediateBuffer4);
 
                         // Compute the Lighting
                         cmd.DispatchCompute(deferredRayTracing, currentKernel, numTilesXHR, numTilesYHR, hdCamera.viewCount);
@@ -380,13 +381,21 @@ void RenderSubsurfaceScattering(HDCamera hdCamera, CommandBuffer cmd, RTHandle c
 
                     // Apply temporal filtering to the buffer
                     HDTemporalFilter temporalFilter = GetTemporalFilter();
-                    temporalFilter.DenoiseBuffer(cmd, hdCamera, diffuseBufferRT, subsurfaceHistory, intermediateBuffer0, singleChannel: false, historyValidity: historyValidity);
+                    temporalFilter.DenoiseBuffer(cmd, hdCamera, intermediateBuffer4, subsurfaceHistory, intermediateBuffer0, singleChannel: false, historyValidity: historyValidity);
+
+                    // Now based on the mask, we need to blend the subsurface and the diffuse lighting
+                    ComputeShader rayTracingSubSurfaceCS = m_Asset.renderPipelineRayTracingResources.subSurfaceRayTracingCS;
+                    int m_CombineSubSurfaceKernel = rayTracingSubSurfaceCS.FindKernel("BlendSubSurfaceData");
+                    cmd.SetComputeTextureParam(rayTracingSubSurfaceCS, m_CombineSubSurfaceKernel, HDShaderIDs._SubSurfaceLightingBuffer, intermediateBuffer0);
+                    cmd.SetComputeTextureParam(rayTracingSubSurfaceCS, m_CombineSubSurfaceKernel, HDShaderIDs._DiffuseLightingTextureRW, diffuseBufferRT);
+                    cmd.SetComputeTextureParam(rayTracingSubSurfaceCS, m_CombineSubSurfaceKernel, HDShaderIDs._SSSBufferTexture, m_SSSColor);
+                    cmd.DispatchCompute(rayTracingSubSurfaceCS, m_CombineSubSurfaceKernel, numTilesXHR, numTilesYHR, hdCamera.viewCount);
 
                     // Push this version of the texture for debug
-                    PushFullScreenDebugTexture(hdCamera, cmd, intermediateBuffer0, FullScreenDebugMode.RayTracedSubSurface);
+                    PushFullScreenDebugTexture(hdCamera, cmd, diffuseBufferRT, FullScreenDebugMode.RayTracedSubSurface);
 
                     // Combine it with the rest of the lighting
-                    m_CombineLightingPass.SetTexture(HDShaderIDs._IrradianceSource, intermediateBuffer0);
+                    m_CombineLightingPass.SetTexture(HDShaderIDs._IrradianceSource, diffuseBufferRT );
                     HDUtils.DrawFullScreen(cmd, m_CombineLightingPass, colorBufferRT, depthStencilBufferRT, shaderPassId: 1);
                 }
             }

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

@@ -48,6 +48,8 @@ partial class HDRenderPipelineRayTracingResources : ScriptableObject
         // Sub-Surface Scattering
         [Reload("Runtime/RenderPipeline/Raytracing/Shaders/RayTracingSubSurface.raytrace")]
         public RayTracingShader subSurfaceRayTracing;
+        [Reload("Runtime/RenderPipeline/Raytracing/Shaders/SubSurface/RayTracingSubSurface.compute")]
+        public ComputeShader subSurfaceRayTracingCS;
 
         // Denoising
         [Reload("Runtime/RenderPipeline/Raytracing/Shaders/Denoising/TemporalFilter.compute")]

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

@@ -601,6 +601,7 @@ static class HDShaderIDs
         public static readonly int _DirectionTextureRW              = Shader.PropertyToID("_DirectionTextureRW");
         public static readonly int _PositionTextureRW               = Shader.PropertyToID("_PositionTextureRW");
         public static readonly int _DiffuseLightingTextureRW        = Shader.PropertyToID("_DiffuseLightingTextureRW");
+        public static readonly int _SubSurfaceLightingBuffer        = Shader.PropertyToID("_SubSurfaceLightingBuffer");
 
         // Accumulation
         public static readonly int _AccumulationFrameIndex          = Shader.PropertyToID("_AccumulationFrameIndex");

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/HDRaytracingManager.cs

@@ -39,7 +39,8 @@ internal enum InternalRayTracingBuffers
         RGBA0,
         RGBA1,
         RGBA2,
-        RGBA3
+        RGBA3,
+        RGBA4
     }
 
     class HDRayTracingLights
@@ -107,6 +108,7 @@ public partial class HDRenderPipeline
         RTHandle m_RayTracingIntermediateBufferRGBA1;
         RTHandle m_RayTracingIntermediateBufferRGBA2;
         RTHandle m_RayTracingIntermediateBufferRGBA3;
+        RTHandle m_RayTracingIntermediateBufferRGBA4;
 
         internal void InitRayTracingManager()
         {
@@ -142,6 +144,8 @@ internal void ReleaseRayTracingManager()
                 RTHandles.Release(m_RayTracingIntermediateBufferRGBA2);
             if (m_RayTracingIntermediateBufferRGBA3 != null)
                 RTHandles.Release(m_RayTracingIntermediateBufferRGBA3);
+            if (m_RayTracingIntermediateBufferRGBA4 != null)
+                RTHandles.Release(m_RayTracingIntermediateBufferRGBA4);
 
             if (m_RayTracingLightCluster != null)
                 m_RayTracingLightCluster.ReleaseResources();
@@ -740,6 +744,11 @@ internal RTHandle AllocateBuffer(InternalRayTracingBuffers bufferID)
                     m_RayTracingIntermediateBufferRGBA3 = RTHandles.Alloc(Vector2.one, TextureXR.slices, colorFormat: GraphicsFormat.R16G16B16A16_SFloat, dimension: TextureXR.dimension, enableRandomWrite: true, useDynamicScale: true, useMipMap: false, name: "RayTracingIntermediateBufferRGBA3");
                     return m_RayTracingIntermediateBufferRGBA3;
                 }
+                case InternalRayTracingBuffers.RGBA4:
+                {
+                    m_RayTracingIntermediateBufferRGBA4 = RTHandles.Alloc(Vector2.one, TextureXR.slices, colorFormat: GraphicsFormat.R16G16B16A16_SFloat, dimension: TextureXR.dimension, enableRandomWrite: true, useDynamicScale: true, useMipMap: false, name: "RayTracingIntermediateBufferRGBA4");
+                    return m_RayTracingIntermediateBufferRGBA4;
+                }
                 default:
                     return null;
             }
@@ -769,6 +778,8 @@ internal RTHandle GetRayTracingBuffer(InternalRayTracingBuffers bufferID)
                     return m_RayTracingIntermediateBufferRGBA2 != null ? m_RayTracingIntermediateBufferRGBA2 : AllocateBuffer(InternalRayTracingBuffers.RGBA2);
                 case InternalRayTracingBuffers.RGBA3:
                     return m_RayTracingIntermediateBufferRGBA3 != null ? m_RayTracingIntermediateBufferRGBA3 : AllocateBuffer(InternalRayTracingBuffers.RGBA3);
+                case InternalRayTracingBuffers.RGBA4:
+                    return m_RayTracingIntermediateBufferRGBA4 != null ? m_RayTracingIntermediateBufferRGBA4 : AllocateBuffer(InternalRayTracingBuffers.RGBA4);
                 default:
                     return null;
             }

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/SubSurface/RayTracingSubSurface.compute

@@ -0,0 +1,48 @@
+#pragma kernel BlendSubSurfaceData
+
+#pragma only_renderers d3d11
+
+// Given that this pass does not use the shadow algorithm multi-compile, we need to define SHADOW_LOW to quite the shadow algorithm error
+#define SHADOW_LOW
+
+// HDRP generic includes
+#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Macros.hlsl"
+#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
+#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Packing.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariablesFunctions.hlsl"
+#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Sampling/Sampling.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/Lighting.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Material.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.hlsl"
+
+// The buffer of sub surface scattering  that was computed used ray tracing
+TEXTURE2D_X(_SubSurfaceLightingBuffer);
+// This buffer holds the diffuse lighting without the SSS contribution
+RW_TEXTURE2D_X(float4, _DiffuseLightingTextureRW);
+
+#define RAYTRACING_SUB_SURFACE_TILE_SIZE 8
+
+[numthreads(RAYTRACING_SUB_SURFACE_TILE_SIZE, RAYTRACING_SUB_SURFACE_TILE_SIZE, 1)]
+void BlendSubSurfaceData(uint3 dispatchThreadId : SV_DispatchThreadID, uint2 groupThreadId : SV_GroupThreadID, uint2 groupId : SV_GroupID)
+{
+    UNITY_XR_ASSIGN_VIEW_INDEX(dispatchThreadId.z);
+
+    // Compute the pixel position to process
+    uint2 currentCoord = groupId * RAYTRACING_SUB_SURFACE_TILE_SIZE + groupThreadId;
+
+    // Read the SSS Data
+    SSSData sssData;
+    DECODE_FROM_SSSBUFFER(currentCoord, sssData);
+
+    // Compute the albedo color to use based on the scattering mode
+    int    profileIndex  = sssData.diffusionProfileIndex;
+    uint   texturingMode = GetSubsurfaceScatteringTexturingMode(profileIndex);
+    float3 albedo        = ApplySubsurfaceScatteringTexturingMode(texturingMode, sssData.diffuseColor);
+
+    // Blend and we are done
+    _DiffuseLightingTextureRW[COORD_TEXTURE2D_X(currentCoord)] = float4(lerp(_DiffuseLightingTextureRW[COORD_TEXTURE2D_X(currentCoord)].xyz * albedo * GetInverseCurrentExposureMultiplier()
+    																	, _SubSurfaceLightingBuffer[COORD_TEXTURE2D_X(currentCoord)].xyz
+    																	, sssData.subsurfaceMask), 1.0);
+}

com.unity.render-pipelines.high-definition/Runtime/RenderPipelineResources/HDRenderPipelineRayTracingResources.asset

@@ -38,6 +38,8 @@ MonoBehaviour:
     type: 3}
   subSurfaceRayTracing: {fileID: 4807578003741378534, guid: b29a18f967c92364492508dddf78cff7,
     type: 3}
+  subSurfaceRayTracingCS: {fileID: 7200000, guid: 4e5684a8dba46fe42a47642f9b0a6b89,
+    type: 3}
   temporalFilterCS: {fileID: 7200000, guid: 741979ff70f7bd6489fbcb464280ecff, type: 3}
   simpleDenoiserCS: {fileID: 7200000, guid: 74a980f1da9a4f842996035350fe756c, type: 3}
   diffuseDenoiserCS: {fileID: 7200000, guid: b4ed2382141619f40af1f743a84ccaea, type: 3}