HDrenderPipeline: Add transmissoin on GI

Assets/ScriptableRenderPipeline/HDRenderPipeline/HDRenderPipeline.cs

 
             InitAndClearBuffer(camera, renderContext);
 
+            PushGlobalParams(hdCamera, renderContext, m_Asset.sssSettings);
+
             RenderDepthPrepass(cullResults, camera, renderContext);
 
             // Forward opaque with deferred/cluster tile require that we fill the depth buffer
                     renderContext.SetupCameraProperties(camera); // Need to recall SetupCameraProperties after m_ShadowPass.Render
                     m_LightLoop.BuildGPULightLists(camera, renderContext, m_CameraDepthStencilBufferRT);
                 }
-
-                PushGlobalParams(hdCamera, renderContext, m_Asset.sssSettings);
 
                 // Caution: We require sun light here as some sky use the sun light to render, mean UpdateSkyEnvironment
                 // must be call after BuildGPULightLists.

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

     // Note that data input above can be use to sample into lightmap (like normal)
     builtinData.bakeDiffuseLighting = SampleBakedGI(input.positionWS, surfaceData.normalWS, input.texCoord1, input.texCoord2);
 
+    // It is safe to call this function here as surfaceData have been filled
+    // We want to know if we must enable transmission on GI for SSS material, if the material have no SSS, this code will be remove by the compiler.
+    BSDFData bsdfData = ConvertSurfaceDataToBSDFData(surfaceData);
+    if (bsdfData.enableTransmission)
+    {
+        // For now simply recall the function with inverted normal, the compiler should be able to optimize the lightmap case to not resample the directional lightmap
+        // however it will not optimize the lightprobe case due to the proxy volume relying on dynamic if (we rely must get right of this dynamic if), not a problem for SH9, but a problem for proxy volume.
+        // TODO: optimize more this code.
+        // Add GI transmission contribution by resampling the GI for inverted vertex normal
+    }
+
     // Emissive Intensity is only use here, but is part of BuiltinData to enforce UI parameters as we want the users to fill one color and one intensity
     builtinData.emissiveIntensity = _EmissiveIntensity; // We still store intensity here so we can reuse it with debug code