Disabled specular occlusion for what we consider medium and larger sc…

…ale rtao > 1.25 with a 25cm falloff interval. (#3023)

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

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

@@ -60,6 +60,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Improved robustness of volumetric sampling in path tracing (case 1295187).
 - Changed the clamping approach for RTR and RTGI (in both perf and quality) to improve visual quality.
 - Changed the warning message for ray traced area shadows (case 1303410).
+- Disabled specular occlusion for what we consider medium and larger scale ao > 1.25 with a 25cm falloff interval.
 
 ## [10.3.0] - 2020-12-01
 

com.unity.render-pipelines.high-definition/Runtime/Debug/DebugDisplay.cs.hlsl

@@ -67,8 +67,7 @@ CBUFFER_START(ShaderVariablesDebugDisplay)
     int _MatcapMixAlbedo;
     float _MatcapViewScale;
     int _DebugSingleShadowIndex;
-    int _DebugProbeVolumeMode;
-    float3 _DebugDisplayPad0;
+    int _DebugDisplayPad0;
 CBUFFER_END
 
 

com.unity.render-pipelines.high-definition/Runtime/Lighting/ScreenSpaceLighting/AmbientOcclusion.cs

@@ -242,6 +242,16 @@ internal void InitRaytracing(HDRenderPipeline renderPipeline)
             m_RaytracingAmbientOcclusion.Init(renderPipeline);
         }
 
+        internal float EvaluateSpecularOcclusionFlag(HDCamera hdCamera)
+        {
+            AmbientOcclusion ssoSettings = hdCamera.volumeStack.GetComponent<AmbientOcclusion>();
+            bool enableRTAO = hdCamera.frameSettings.IsEnabled(FrameSettingsField.RayTracing) && ssoSettings.rayTracing.value;
+            if (enableRTAO)
+                return m_RaytracingAmbientOcclusion.EvaluateRTSpecularOcclusionFlag(hdCamera, ssoSettings);
+            else
+                return 1.0f;
+        }
+
         internal bool IsActive(HDCamera camera, AmbientOcclusion settings) => camera.frameSettings.IsEnabled(FrameSettingsField.SSAO) && settings.intensity.value > 0f;
 
         struct RenderAOParameters

com.unity.render-pipelines.high-definition/Runtime/Material/MaterialEvaluation.hlsl

@@ -98,7 +98,7 @@ void GetScreenSpaceAmbientOcclusionMultibounce(float2 positionSS, float NdotV, f
     float directAmbientOcclusion = lerp(1.0, indirectAmbientOcclusion, _AmbientOcclusionParam.w);
 
     float roughness = PerceptualRoughnessToRoughness(perceptualRoughness);
-    float indirectSpecularOcclusion = GetSpecularOcclusionFromAmbientOcclusion(ClampNdotV(NdotV), indirectAmbientOcclusion, roughness);
+    float indirectSpecularOcclusion = lerp(1.0, GetSpecularOcclusionFromAmbientOcclusion(ClampNdotV(NdotV), indirectAmbientOcclusion, roughness), _SpecularOcclusionBlend);
     float directSpecularOcclusion = lerp(1.0, indirectSpecularOcclusion, _AmbientOcclusionParam.w);
 
     aoFactor.indirectSpecularOcclusion = GTAOMultiBounce(min(specularOcclusionFromData, indirectSpecularOcclusion), fresnel0);

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

@@ -1039,11 +1039,14 @@ void UpdateShaderVariablesGlobalCB(HDCamera hdCamera, CommandBuffer cmd)
                 m_ShaderVariablesGlobalCB._EnableRayTracedReflections = enableRaytracedReflections ? 1 : 0;
                 RecursiveRendering recursiveSettings = hdCamera.volumeStack.GetComponent<RecursiveRendering>();
                 m_ShaderVariablesGlobalCB._EnableRecursiveRayTracing = recursiveSettings.enable.value ? 1u : 0u;
+
+                m_ShaderVariablesGlobalCB._SpecularOcclusionBlend = m_AmbientOcclusionSystem.EvaluateSpecularOcclusionFlag(hdCamera);
             }
             else
             {
                 m_ShaderVariablesGlobalCB._EnableRayTracedReflections = 0;
                 m_ShaderVariablesGlobalCB._EnableRecursiveRayTracing = 0;
+                m_ShaderVariablesGlobalCB._SpecularOcclusionBlend = 0.0f;
             }
 
             ConstantBuffer.PushGlobal(cmd, m_ShaderVariablesGlobalCB, HDShaderIDs._ShaderVariablesGlobal);

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

@@ -28,6 +28,12 @@ public void Init(HDRenderPipeline renderPipeline)
             m_RTAOApplyIntensityKernel = m_PipelineRayTracingResources.aoRaytracingCS.FindKernel("RTAOApplyIntensity");
         }
 
+        public float EvaluateRTSpecularOcclusionFlag(HDCamera hdCamera, AmbientOcclusion ssoSettings)
+        {
+            float remappedRayLength = (Mathf.Clamp(ssoSettings.rayLength, 1.25f, 1.5f) - 1.25f) / 0.25f;
+            return Mathf.Lerp(0.0f, 1.0f, 1.0f - remappedRayLength);
+        }
+
         static RTHandle AmbientOcclusionHistoryBufferAllocatorFunction(string viewName, int frameIndex, RTHandleSystem rtHandleSystem)
         {
             return rtHandleSystem.Alloc(Vector2.one, TextureXR.slices, colorFormat: GraphicsFormat.R16G16_SFloat, dimension: TextureXR.dimension,

com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariablesGlobal.cs

@@ -268,7 +268,7 @@ unsafe struct ShaderVariablesGlobal
         // Because the DepthPrepass doesn't have a DEBUG_DISPLAY variant, it is the only way to disable it for debug modes
         public float    _GlobalTessellationFactorMultiplier;
 
-        public float    _Pad8;
+        public float    _SpecularOcclusionBlend;
         public float    _Pad9;
     }
 }

com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariablesGlobal.cs.hlsl

@@ -151,7 +151,7 @@ GLOBAL_CBUFFER_START(ShaderVariablesGlobal, b0)
     float4 _ProbeVolumeAmbientProbeFallbackPackedCoeffs[7];
     int _TransparentCameraOnlyMotionVectors;
     float _GlobalTessellationFactorMultiplier;
-    float _Pad8;
+    float _SpecularOcclusionBlend;
     float _Pad9;
 CBUFFER_END