Fixed the emissive being overriden by ray traced sub-surface scattering (case 1364456). (#5636)

* Fixed the emissive being overriden by ray traced sub-surface scattering (case 1364456).

* updating doc

* Fix formatting

Co-authored-by: sebastienlagarde <[email protected]>

Author: anisunity

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

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed error when disabling opaque objects on a camera with MSAA.
 - Fixed double camera preview.
 - Fixed the volumetric clouds cloud map not being centered over the world origin (case 1364465).
+- Fixed the emissive being overriden by ray traced sub-surface scattering (case 1364456).
 
 ### Changed
 - Visual Environment ambient mode is now Dynamic by default.

com.unity.render-pipelines.high-definition/Documentation~/Ray-Traced-Subsurface-Scattering.md

@@ -19,3 +19,6 @@ Ray traced subsurface scattering uses the [Volume](Volumes.md) framework, so to
 | Property       | Description                                                  |
 | -------------- | ------------------------------------------------------------ |
 | **Sample Count**  | Defines the number of samples that are cast per pixel to evaluate the subsurface scattering lighting. |
+
+## Limitations
+* Emissive surfaces are incompatible with ray traced sub-surface scattering.

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassRayTracingSubSurface.hlsl

@@ -30,7 +30,8 @@ void ClosestSubSurface(inout RayIntersectionSubSurface rayIntersection : SV_RayP
     bool isVisible;
     GetSurfaceAndBuiltinData(fragInput, -incidentDirection, posInput, surfaceData, builtinData, currentVertex, rayIntersection.cone, isVisible);
 
-    // make sure we output the normal and the indirect diffuse lighting value
+    // make sure we output the normal
     rayIntersection.outNormal = fragInput.tangentToWorld[2];
-    rayIntersection.outIndirectDiffuse = builtinData.bakeDiffuseLighting;
+    // Make sure to output the indirect diffuse lighting value and the emissive value
+    rayIntersection.outIndirectDiffuse = builtinData.bakeDiffuseLighting + builtinData.emissiveColor;
 }