Add additional shader passes + clean-up

Assets/ScriptableRenderPipeline/Core/ShaderLibrary/Common.hlsl

     return positionVS.xyz / positionVS.w;
 }
 
+float3 ComputeWorldSpacePosition(float2 positionSS, float depthRaw, float4x4 invViewProjMatrix)
+{
+    float4 positionCS  = ComputeClipSpacePosition(positionSS, depthRaw);
+    float4 hpositionWS = mul(invViewProjMatrix, positionCS);
+    return hpositionWS.xyz / hpositionWS.w;
+}
+
 // From deferred or compute shader
 // depth must be the depth from the raw depth buffer. This allow to handle all kind of depth automatically with the inverse view projection matrix.
 // For information. In Unity Depth is always in range 0..1 (even on OpenGL) but can be reversed.
 
-    float4 positionCS   = ComputeClipSpacePosition(posInput.positionSS, depthRaw);
-    float4 hpositionWS  = mul(invViewProjMatrix, positionCS);
-    posInput.positionWS = hpositionWS.xyz / hpositionWS.w;
+    posInput.positionWS = ComputeWorldSpacePosition(posInput.positionSS, depthRaw, invViewProjMatrix);
 
     // The compiler should optimize this (less expensive than reconstruct depth VS from depth buffer)
     posInput.depthVS = mul(viewProjMatrix, float4(posInput.positionWS, 1.0)).w;

Assets/ScriptableRenderPipeline/HDRenderPipeline/Lighting/TilePass/Deferred.compute

 // deferred material must replace the old one here. If in the future we want to support multiple layout (cause a lot of consistency problem),
 // the deferred shader will require to use multicompile.
 #define UNITY_MATERIAL_LIT // Need to be define before including Material.hlsl
-#include "../../ShaderConfig.cs.hlsl"
 #include "../../ShaderVariables.hlsl"
 #include "../../Lighting/Lighting.hlsl" // This include Material.hlsl
 

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.hlsl

 
     bool performPostScatterTexturing = IsBitSet(_TexturingModeFlags, subsurfaceProfile);
 
-    bool enableSssAndTransmission = true;
-
-    enableSssAndTransmission = false;
-#elif (SSS_PASS == 0)
-    enableSssAndTransmission = _EnableSSSAndTransmission != 0;
+    bool enableSssAndTransmission = false;
+#elif defined(SHADERPASS) && (SHADERPASS == SHADERPASS_SUBSURFACE_SCATTERING)
+    bool enableSssAndTransmission = true;
+#else
+    bool enableSssAndTransmission = _EnableSSSAndTransmission != 0;
 #endif
 
     if (enableSssAndTransmission) // If we globally disable SSS effect, don't modify diffuseColor
         {
-        #ifndef SSS_PASS
+        #if !defined(SHADERPASS) || (SHADERPASS != SHADERPASS_SUBSURFACE_SCATTERING)
             bsdfData.diffuseColor = float3(1.0, 1.0, 1.0);
         #endif
         }

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Resources/SubsurfaceScattering.compute

 #define SSS_DEBUG_NORMAL_VS   0
 
 // Do not modify these.
-#define SSS_PASS              1
+#include "../../../ShaderPass/ShaderPass.cs.hlsl"
+#define SHADERPASS            SHADERPASS_SUBSURFACE_SCATTERING
 #define MILLIMETERS_PER_METER 1000
 #define CENTIMETERS_PER_METER 100
 #define GROUP_SIZE_1D         16

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Resources/SubsurfaceScattering.shader

             #pragma multi_compile _ SSS_FILTER_HORIZONTAL_AND_COMBINE
 
             // Do not modify these.
-            #define SSS_PASS              1
+            #include "../../../ShaderPass/ShaderPass.cs.hlsl"
+            #define SHADERPASS            SHADERPASS_SUBSURFACE_SCATTERING
             #define MILLIMETERS_PER_METER 1000
             #define CENTIMETERS_PER_METER 100
 

Assets/ScriptableRenderPipeline/HDRenderPipeline/ShaderPass/ShaderPass.cs

         Velocity,
         Distortion,
         LightTransport,
-        Shadows
+        Shadows,
+        SubsurfaceScattering,
+        VolumetricLighting
     }
 }

Assets/ScriptableRenderPipeline/HDRenderPipeline/ShaderPass/ShaderPass.cs.hlsl

 #define SHADERPASS_DISTORTION (5)
 #define SHADERPASS_LIGHT_TRANSPORT (6)
 #define SHADERPASS_SHADOWS (7)
+#define SHADERPASS_SUBSURFACE_SCATTERING (8)
+#define SHADERPASS_VOLUMETRIC_LIGHTING (9)
 
 
 #endif