Added new Shadow SSS Lut;

Fixed the issue that SSGI and SSAO weight not works properly;

Editor/SSS/SSSLutBaker.compute

@@ -1,9 +1,14 @@
-#pragma kernel CSMain
+#pragma kernel SkinLut
+#pragma kernel ShadowLut
+
 #pragma multi_compile_local _ _PRODUCTION
 
 #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
 
+#define _PROFILE_WIDTH 8.166
+
 float _ScatterRadius;
+float _PositionShift;
 float _Intensity;
 int _SampleCount;
 int _ApplyTonemap;
@@ -51,12 +56,11 @@ float3 RadianceScatter(float r)
 
 float3 IntegrateDiffuseScattering_Ring(float theta, float r)
 {
-    float x = -HALF_PI;
-    float increment = PI / _SampleCount;
-    
     float3 totalScatter = 0;
     float3 totalWeight = 0;
+    float increment = PI / _SampleCount;
     
+    float x = -HALF_PI;
     while (x < HALF_PI)
     {
         float diffuse = saturate(cos(theta + x));
@@ -72,13 +76,42 @@ float3 IntegrateDiffuseScattering_Ring(float theta, float r)
     return totalScatter / totalWeight;
 }
 
+float newPenumbra(float pos, float penumbraWidth)
+{
+    return saturate((pos * penumbraWidth - _PROFILE_WIDTH) / (penumbraWidth - _PROFILE_WIDTH));
+}
+
+float3 IntegrateShadowScattering(float penumbraLocation, float penumbraWidth)
+{
+    float3 totalScatter = 0;
+    float3 totalWeights = 0;
+    float increment = (_PROFILE_WIDTH * 2) / _SampleCount;
+
+    penumbraWidth = max(penumbraWidth, _PROFILE_WIDTH + 1e-5);
+    
+    float x = -_PROFILE_WIDTH;
+    while (x <= _PROFILE_WIDTH)
+    {
+        float light = newPenumbra(penumbraLocation + x / penumbraWidth, penumbraWidth);
+        float distance = abs(x);
+        float3 weights = RadianceScatter(distance);
+        
+        totalWeights += weights;
+        totalScatter += light * weights;
+        
+        x += increment;
+    }
+
+    return totalScatter / totalWeights;
+}
+
 float3 FilmicTonemap(float3 color)
 {
     return (color * (6.2 * color + 0.5)) / (color * (6.2 * color + 1.7) + 0.06);
 }
 
 [numthreads(8,8,1)]
-void CSMain (uint3 id : SV_DispatchThreadID)
+void SkinLut (uint3 id : SV_DispatchThreadID)
 {
     if (id.x > _TextureSize || id.y > _TextureSize)
     {
@@ -90,7 +123,7 @@ void CSMain (uint3 id : SV_DispatchThreadID)
     uv.y = 1.0 - uv.y;
 #endif
     
-    float theta = acos(uv.x * 2.0 - 1.0);
+    float theta = acos((uv.x * 2.0 - 1.0)) + _PositionShift;
     float r = rcp(max(uv.y, 0.001) * _ScatterRadius);
     
     float3 scatter = IntegrateDiffuseScattering_Ring(theta, r) * _Intensity;
@@ -99,5 +132,31 @@ void CSMain (uint3 id : SV_DispatchThreadID)
         scatter = FilmicTonemap(scatter);
     }
     
+    _SSSLut[id.xy] = float4(scatter, 1.0);
+    //_SSSLut[id.xy] = theta;
+}
+
+[numthreads(8, 8, 1)]
+void ShadowLut(uint3 id : SV_DispatchThreadID)
+{
+    if (id.x > _TextureSize || id.y > _TextureSize)
+    {
+        return;
+    }
+    
+    float2 uv = id.xy / float2(_TextureSize, _TextureSize);
+#if UNITY_UV_STARTS_AT_TOP && _PRODUCTION
+    uv.y = 1.0 - uv.y;
+#endif
+    
+    float penumbraLocation = uv.x + _PositionShift;
+    float penumbraWidth = rcp(max(uv.y, 0.001) * _ScatterRadius);
+    
+    float3 scatter = IntegrateShadowScattering(penumbraLocation, penumbraWidth) * _Intensity;
+    if (_ApplyTonemap == 1)
+    {
+        scatter = FilmicTonemap(scatter);
+    }
+    
     _SSSLut[id.xy] = float4(scatter, 1.0);
 }

Editor/SSS/SSSLutBakerView.cs

@@ -37,7 +37,9 @@ namespace Misaki.HdrpToon.Editor
         private RenderTexture _previewTexture;
         private RenderTextureDescriptor _previewDescriptor;
 
+        public bool isShadowLut;
         public float scatterRadius = 1.0f;
+        public float positionShift = 0.0f;
         public float intensity = 1.0f;
         public Quality sampleCount = Quality.Low;
         public bool applyTonemap = true;
@@ -78,7 +80,10 @@ namespace Misaki.HdrpToon.Editor
                 return false;
             }
 
+            var kernelIndex = isShadowLut ? 1 : 0;
+
             _bakerShader.SetFloat("_ScatterRadius", scatterRadius);
+            _bakerShader.SetFloat("_PositionShift", positionShift);
             _bakerShader.SetFloat("_Intensity", intensity);
             _bakerShader.SetInt("_SampleCount", (int)sampleCount);
             _bakerShader.SetInt("_ApplyTonemap", applyTonemap ? 1 : 0);
@@ -86,13 +91,13 @@ namespace Misaki.HdrpToon.Editor
 
             _bakerShader.SetKeyword(new LocalKeyword(_bakerShader, "_PRODUCTION"), production);
 
-            _bakerShader.SetTexture(0, "_SSSLut", texture);
+            _bakerShader.SetTexture(kernelIndex, "_SSSLut", texture);
 
             const int groupSizeX = 8;
             const int groupSizeY = 8;
             var threadGroupX = (textureSize + (groupSizeX - 1)) / groupSizeX;
             var threadGroupY = (textureSize + (groupSizeY - 1)) / groupSizeY;
-            _bakerShader.Dispatch(0, threadGroupX, threadGroupY, 1);
+            _bakerShader.Dispatch(kernelIndex, threadGroupX, threadGroupY, 1);
 
             return true;
         }

Editor/SSS/SSSLutBakerView.uxml

@@ -2,11 +2,21 @@
     <engine:VisualElement data-source-type="Misaki.HdrpToon.Editor.SSSLutBakerView, Misaki.HdrpToon.Editor" style="flex-grow: 1; padding-top: 8px; padding-right: 8px; padding-bottom: 8px; padding-left: 8px;">
         <engine:Label text="SSS Lut Baker" style="font-size: 18px; padding-top: 0; padding-right: 0; padding-bottom: 0; padding-left: 0; margin-top: 12px; margin-bottom: 8px; margin-left: 4px; margin-right: 6px; -unity-font-style: bold;" />
         <engine:Label text="Parameters:" style="-unity-font-style: bold; margin-top: 12px; margin-bottom: 4px; margin-right: 2px; margin-left: 2px;" />
+        <engine:DropdownField label="Lut Type" choices="Skin,Shadow" index="0">
+            <Bindings>
+                <engine:DataBinding property="index" data-source-path="isShadowLut" binding-mode="TwoWay" />
+            </Bindings>
+        </engine:DropdownField>
         <engine:FloatField label="Scatter Radius" value="1">
             <Bindings>
                 <engine:DataBinding property="value" data-source-path="scatterRadius" binding-mode="TwoWay" />
             </Bindings>
         </engine:FloatField>
+        <engine:Slider label="Position Shift" value="0.0" low-value="-1" high-value="1" page-size="0.1" show-input-field="true">
+            <Bindings>
+                <engine:DataBinding property="value" data-source-path="positionShift" binding-mode="TwoWay" />
+            </Bindings>
+        </engine:Slider>
         <engine:Slider label="Intensity" value="1" high-value="10" show-input-field="true" page-size="0.1">
             <Bindings>
                 <engine:DataBinding property="value" data-source-path="intensity" binding-mode="TwoWay" />