[HDRP][Ray Tracing] Only meshes with HDRP materials are added to the acceleration structure

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

@@ -217,6 +217,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Increased path tracing max samples from 4K to 16K (case 1327729).
 - Film grain does not affect the alpha channel.
 - Disable TAA sharpening on alpha channel.
+- Changed ray tracing acceleration structure build, so that only meshes with HDRP materials are included (case 1322365).
 
 ## [11.0.0] - 2020-10-21
 

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

@@ -74,6 +74,7 @@ public partial class HDRenderPipeline
         RayTracingSubMeshFlags[] subMeshFlagArray = new RayTracingSubMeshFlags[maxNumSubMeshes];
         ReflectionProbe reflectionProbe = new ReflectionProbe();
         List<Material> materialArray = new List<Material>(maxNumSubMeshes);
+        Dictionary<int, bool> m_ShaderValidityCache = new Dictionary<int, bool>();
 
         // Used to detect material and transform changes for Path Tracing
         Dictionary<int, int> m_MaterialCRCs = new Dictionary<int, int>();
@@ -114,6 +115,26 @@ internal void ReleaseRayTracingManager()
                 m_DiffuseDenoiser.Release();
         }
 
+        bool IsValidRayTracedMaterial(Material currentMaterial)
+        {
+            if (currentMaterial == null || currentMaterial.shader == null)
+                return false;
+
+            bool isValid;
+
+            // We use a cache, to speed up the case where materials/shaders are reused many times
+            int shaderId = currentMaterial.shader.GetInstanceID();
+            if (m_ShaderValidityCache.TryGetValue(shaderId, out isValid))
+                return isValid;
+
+            // For the time being, we only consider non-decal HDRP materials as valid
+            isValid = currentMaterial.GetTag("RenderPipeline", false) == "HDRenderPipeline" && !DecalSystem.IsDecalMaterial(currentMaterial);
+
+            m_ShaderValidityCache.Add(shaderId, isValid);
+
+            return isValid;
+        }
+
         static bool IsTransparentMaterial(Material currentMaterial)
         {
             return currentMaterial.IsKeywordEnabled("_SURFACE_TYPE_TRANSPARENT")
@@ -184,8 +205,8 @@ AccelerationStructureStatus AddInstanceToRAS(Renderer currentRenderer,
                     // Grab the material for the current sub-mesh
                     Material currentMaterial = materialArray[meshIdx];
 
-                    // Make sure that the material is both non-null and non-decal
-                    if (currentMaterial != null && !DecalSystem.IsDecalMaterial(currentMaterial))
+                    // Make sure that the material is HDRP's and non-decal
+                    if (IsValidRayTracedMaterial(currentMaterial))
                     {
                         // Mesh is valid given that all requirements are ok
                         validMesh = true;