Fog volumetric scattering for path tracing (#2110)

eturquin · sebastienlagarde · web-flow · commit e3fd1e26602c · 2020-10-25T15:57:39.000+01:00
* Brought changes from volume branch.

* Minor fixes on cone region of spot lights.

* Re-added mistakenly removed headers from the PT pass of Unlit &amp; Lit.

* Added clamping on cam ray misses with vol scattering.

* Minor tweaks.

* Added support for box and pyramid point lights.

* Updated changelog.

* Added vol light intensity multiplier support.

* Added support for box and pyramid spot lights.

* Updated Changelog.

* Reverted unwanted changes to diffusion profile asset.

* ...

* FFS

* Added better path tracing support in shader graph.

* Fix PT directional light activation for null radius.

* Updated png reference images, to account for sampling seq changes.

Co-authored-by: sebastienlagarde &lt;sebastien@unity3d.com&gt;
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diff --git a/com.unity.render-pipelines.high-definition/CHANGELOG.md b/com.unity.render-pipelines.high-definition/CHANGELOG.md
@@ -21,6 +21,7 @@ The version number for this package has increased due to a version update of a r
 - Added frame setting for Virtual Texturing. 
 - Added a fade distance for light influencing volumetric lighting.
 - Adding an "Include For Ray Tracing" toggle on lights to allow the user to exclude them when ray tracing is enabled in the frame settings of a camera.
+- Added fog volumetric scattering support for path tracing.
 
 ### Fixed
 - Fixed an issue where the Exposure Shader Graph node had clipped text. (case 1265057)
diff --git a/com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/HDLitSubTarget.cs b/com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/HDLitSubTarget.cs
@@ -46,6 +46,7 @@ public HDLitData litData
         protected override string postDecalsInclude => "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitDecalData.hlsl";
         protected override ShaderID shaderID => HDShaderUtils.ShaderID.SG_Lit;
         protected override string raytracingInclude => CoreIncludes.kLitRaytracing;
+        protected override string pathtracingInclude => CoreIncludes.kLitPathtracing;
         protected override FieldDescriptor subShaderField => new FieldDescriptor(kSubShader, "Lit Subshader", "");
         protected override string subShaderInclude => CoreIncludes.kLit;
 
diff --git a/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDShaderPasses.cs b/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDShaderPasses.cs
@@ -1115,8 +1115,8 @@ IncludeCollection GenerateIncludes()
 
                 // Each material has a specific hlsl file that should be included pre-graph and holds the lighting model
                 includes.Add(CoreIncludes.kPassPlaceholder, IncludeLocation.Pregraph);
-                // We need to then include the ray tracing missing bits for the lighting models (based on which lighting model)
-                includes.Add(CoreIncludes.kRaytracingPlaceholder, IncludeLocation.Pregraph);
+                // We need to then include path tracing support for the material
+                includes.Add(CoreIncludes.kPathtracingPlaceholder, IncludeLocation.Pregraph);
 
                 includes.Add(CoreIncludes.CoreUtility);
                 includes.Add(CoreIncludes.kRaytracingCommon, IncludeLocation.Pregraph);
diff --git a/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDSubTarget.cs b/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDSubTarget.cs
@@ -50,6 +50,7 @@ public SystemData systemData
 
         protected virtual string postDecalsInclude => null;
         protected virtual string raytracingInclude => null;
+        protected virtual string pathtracingInclude => null;
         protected virtual bool supportPathtracing => false;
         protected virtual bool supportRaytracing => false;
 
@@ -148,6 +149,8 @@ protected SubShaderDescriptor PostProcessSubShader(SubShaderDescriptor subShader
                         include.descriptor.value = postDecalsInclude;
                     if (include.descriptor.value == CoreIncludes.kRaytracingPlaceholder)
                         include.descriptor.value = raytracingInclude;
+                    if (include.descriptor.value == CoreIncludes.kPathtracingPlaceholder)
+                        include.descriptor.value = pathtracingInclude;
 
                     if (!String.IsNullOrEmpty(include.descriptor.value))
                         finalIncludes.Add(include.descriptor.value, include.descriptor.location, include.fieldConditions);
diff --git a/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDTarget.cs b/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/HDTarget.cs
@@ -873,6 +873,7 @@ static class CoreIncludes
         public const string kRaytracingIntersectionGBuffer = "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/Deferred/RaytracingIntersectonGBuffer.hlsl";
         public const string kRaytracingIntersectionSubSurface = "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/SubSurface/RayTracingIntersectionSubSurface.hlsl";
         public const string kLitRaytracing = "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitRaytracing.hlsl";
+        public const string kLitPathtracing = "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitPathTracing.hlsl";
         public const string kUnlitRaytracing = "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Unlit/UnlitRaytracing.hlsl";
         public const string kFabricRaytracing = "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Fabric/FabricRaytracing.hlsl";
         public const string kEyeRaytracing = "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Eye/EyeRaytracing.hlsl";
@@ -913,6 +914,7 @@ static class CoreIncludes
         public const string kPassPlaceholder = "Pass Include Placeholder, replace me !";
         public const string kPostDecalsPlaceholder = "After Decal Include Placeholder, replace me !";
         public const string kRaytracingPlaceholder = "Raytracing Include Placeholder, replace me !";
+        public const string kPathtracingPlaceholder = "Pathtracing Include Placeholder, replace me !";
 
         // Public Postgraph Pass
         public const string kPassLightTransport = "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassLightTransport.hlsl";
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightEvaluation.hlsl b/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightEvaluation.hlsl
@@ -1,3 +1,6 @@
+#ifndef UNITY_LIGHT_EVALUATION_INCLUDED
+#define UNITY_LIGHT_EVALUATION_INCLUDED
+
 // This files include various function uses to evaluate lights
 // use #define LIGHT_EVALUATION_NO_HEIGHT_FOG to disable Height fog attenuation evaluation
 // use #define LIGHT_EVALUATION_NO_COOKIE to disable cookie evaluation
@@ -582,3 +585,5 @@ void ApplyScreenSpaceReflectionWeight(inout float4 ssrLighting)
     ssrLighting.rgb *= ssrLighting.a;
 }
 #endif
+
+#endif // UNITY_LIGHT_EVALUATION_INCLUDED
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/CookieSampling.hlsl b/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/CookieSampling.hlsl
@@ -1,3 +1,6 @@
+#ifndef UNITY_COOKIE_SAMPLING_INCLUDED
+#define UNITY_COOKIE_SAMPLING_INCLUDED
+
 //-----------------------------------------------------------------------------
 // Cookie sampling functions
 // ----------------------------------------------------------------------------
@@ -47,3 +50,5 @@ float3 SamplePointCookie(float3 lightToSample, float4 scaleOffset, float lod = 0
 
     return SampleCookie2D(uv, scaleOffset, lod);
 }
+
+#endif // UNITY_COOKIE_SAMPLING_INCLUDED
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl b/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl
@@ -1,3 +1,6 @@
+#ifndef UNITY_LIGHT_LOOP_DEF_INCLUDED
+#define UNITY_LIGHT_LOOP_DEF_INCLUDED
+
 #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoop.cs.hlsl"
 #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/CookieSampling.hlsl"
 
@@ -375,3 +378,5 @@ float3 GetScreenSpaceColorShadow(PositionInputs posInput, int shadowIndex)
     float4 res = LOAD_TEXTURE2D_ARRAY(_ScreenSpaceShadowsTexture, posInput.positionSS, INDEX_TEXTURE2D_ARRAY_X(shadowIndex & SCREEN_SPACE_SHADOW_INDEX_MASK));
     return (SCREEN_SPACE_COLOR_SHADOW_FLAG & shadowIndex) ? res.xyz : res.xxx;
 }
+
+#endif // UNITY_LIGHT_LOOP_DEF_INCLUDED
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Material/LayeredLit/LayeredLit.shader b/com.unity.render-pipelines.high-definition/Runtime/Material/LayeredLit/LayeredLit.shader
@@ -1137,19 +1137,17 @@ Shader "HDRP/LayeredLit"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Material.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/ShaderVariablesRaytracing.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/ShaderVariablesRaytracingLightLoop.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/Lighting.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/ShaderPass/LitSharePass.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingIntersection.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl"
             #define HAS_LIGHTLOOP
+            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RayTracingCommon.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitRaytracing.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingLightLoop.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/LayeredLit/LayeredLitData.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RayTracingCommon.hlsl"
+            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitPathTracing.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassPathTracing.hlsl"
 
             ENDHLSL
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.shader b/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.shader
@@ -1153,26 +1153,24 @@ Shader "HDRP/Lit"
 
             #define SHADERPASS SHADERPASS_PATH_TRACING
 
-            // This is just because it need to be defined, shadow maps are not used.
+            // This is just because it needs to be defined, shadow maps are not used.
             #define SHADOW_LOW
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingMacros.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Material.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/ShaderVariablesRaytracing.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/ShaderVariablesRaytracingLightLoop.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/Lighting.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/ShaderPass/LitSharePass.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingIntersection.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl"
             #define HAS_LIGHTLOOP
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitRaytracing.hlsl"
-            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingLightLoop.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RayTracingCommon.hlsl"
+            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitData.hlsl"
+            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Lit/LitPathTracing.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassPathTracing.hlsl"
 
             ENDHLSL
diff --git a/com.unity.render-pipelines.high-definition/Runtime/Material/Unlit/Unlit.shader b/com.unity.render-pipelines.high-definition/Runtime/Material/Unlit/Unlit.shader
@@ -606,6 +606,9 @@ Shader "HDRP/Unlit"
 
             #define SHADERPASS SHADERPASS_PATH_TRACING
 
+            #define SHADER_UNLIT
+            #define HAS_LIGHTLOOP // Used when computing volumetric scattering
+
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingMacros.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
@@ -616,7 +619,6 @@ Shader "HDRP/Unlit"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingIntersection.hlsl"
 
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Unlit/Unlit.hlsl"
-
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Unlit/UnlitData.hlsl"
             #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassPathTracing.hlsl"
 
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Accumulation/SubFrameManager.cs b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Accumulation/SubFrameManager.cs
@@ -311,7 +311,7 @@ RenderAccumulationParameters PrepareRenderAccumulationParameters(HDCamera hdCame
 
         void RenderAccumulation(HDCamera hdCamera, RTHandle inputTexture, RTHandle outputTexture, bool needExposure, CommandBuffer cmd)
         {
-            // Grab the history buffer (hijack the reflections one)
+            // Grab the history buffer
             RTHandle history = hdCamera.GetCurrentFrameRT((int)HDCameraFrameHistoryType.PathTracing)
                 ?? hdCamera.AllocHistoryFrameRT((int)HDCameraFrameHistoryType.PathTracing, PathTracingHistoryBufferAllocatorFunction, 1);
 
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.RenderGraph.cs b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.RenderGraph.cs
@@ -1406,7 +1406,7 @@ void RenderAccumulation(RenderGraph renderGraph, HDCamera hdCamera, TextureHandl
         {
             using (var builder = renderGraph.AddRenderPass<RenderAccumulationPassData>("Render Accumulation", out var passData))
             {
-                // Grab the history buffer (hijack the reflections one)
+                // Grab the history buffer
                 TextureHandle history = renderGraph.ImportTexture(hdCamera.GetCurrentFrameRT((int)HDCameraFrameHistoryType.PathTracing)
                     ?? hdCamera.AllocHistoryFrameRT((int)HDCameraFrameHistoryType.PathTracing, PathTracingHistoryBufferAllocatorFunction, 1));
 
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingBSDF.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingBSDF.hlsl
@@ -1,6 +1,7 @@
 #ifndef UNITY_PATH_TRACING_BSDF_INCLUDED
 #define UNITY_PATH_TRACING_BSDF_INCLUDED
 
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingSampling.hlsl"
 #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/SubSurface.hlsl"
 
 #define DELTA_PDF 1000000.0
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingLight.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingLight.hlsl
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingMain.raytrace b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingMain.raytrace
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingSampling.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingSampling.hlsl
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingVolume.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingVolume.hlsl
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingVolume.hlsl.meta b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/Shaders/PathTracingVolume.hlsl.meta
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/Common/AtmosphericScatteringRayTracing.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/Common/AtmosphericScatteringRayTracing.hlsl
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingSampling.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Raytracing/Shaders/RaytracingSampling.hlsl
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassPathTracing.hlsl b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassPathTracing.hlsl
