Fix issue with smoothness and sky lighting

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightLoop/LightLoopDef.hlsl

 #define SINGLE_PASS_CONTEXT_SAMPLE_REFLECTION_PROBES 0
 #define SINGLE_PASS_CONTEXT_SAMPLE_SKY 1
 
+// The EnvLightData of the sky light contains a bunch of compile-time constants.
+// This function sets them directly to allow the compiler to propagate them and optimize the code.
+EnvLightData InitSkyEnvLightData(int envIndex)
+{
+    EnvLightData output;
+    ZERO_INITIALIZE(EnvLightData, output);
+    output.influenceShapeType = ENVSHAPETYPE_SKY;
+    // 31 bit index, 1 bit cache type
+    output.envIndex = ENVCACHETYPE_CUBEMAP | (envIndex << 1);
+
+    output.influenceForward = float3(0.0, 0.0, 1.0);
+    output.influenceUp = float3(0.0, 1.0, 0.0);
+    output.influenceRight = float3(1.0, 0.0, 0.0);
+    output.influencePositionWS = float3(0.0, 0.0, 0.0);
+
+    output.weight = 1.0;
+    output.multiplier = 1.0;
+
+    // proxy
+    output.proxyForward = float3(0.0, 0.0, 1.0);
+    output.proxyUp = float3(0.0, 1.0, 0.0);
+    output.proxyRight = float3(1.0, 0.0, 0.0);
+    output.minProjectionDistance = 65504.0f;
+
+    return output;
+}
+
 bool IsEnvIndexCubemap(int index)   { return (index & 1) == ENVCACHETYPE_CUBEMAP; }
 bool IsEnvIndexTexture2D(int index) { return (index & 1) == ENVCACHETYPE_TEXTURE2D; }
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/Lighting.hlsl

 #define HAS_LIGHTLOOP // Allow to not define LightLoop related function in Material.hlsl
 
 #include "../Lighting/LightDefinition.cs.hlsl"
-#include "../Lighting/LightUtilities.hlsl"
 
 #include "LightLoop/Shadow.hlsl"
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/Lit.hlsl

     R = lerp(R, preLightData.iblR, saturate(smoothstep(0, 1, roughness * roughness)));
 
     float3 F = preLightData.specularFGD;
-    float iblMipLevel = PerceptualRoughnessToMipmapLevel(preLightData.iblPerceptualRoughness);
-    // Specific case for Texture2Ds, their convolution is a gaussian one and not a GGX one.
-    // So we use another roughness mip mapping.
+    float iblMipLevel;
+    // TODO: We need to match the PerceptualRoughnessToMipmapLevel formula for planar, so we don't do this test (which is specific to our current lightloop)
+    // Specific case for Texture2Ds, their convolution is a gaussian one and not a GGX one - So we use another roughness mip mapping.
+    }
+    else
+    {
+        iblMipLevel = PerceptualRoughnessToMipmapLevel(preLightData.iblPerceptualRoughness);
     }
 
     float4 preLD = SampleEnv(lightLoopContext, lightData.envIndex, R, iblMipLevel);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/StackLit/StackLit.hlsl

         R[i] = lerp(R[i], preLightData.iblR[i], saturate(smoothstep(0, 1, roughness * roughness)));
 
 
-        float iblMipLevel = PerceptualRoughnessToMipmapLevel(preLightData.iblPerceptualRoughness[i]);
+        float iblMipLevel;
+        // TODO: We need to match the PerceptualRoughnessToMipmapLevel formula for planar, so we don't do this test (which is specific to our current lightloop)
+        // Specific case for Texture2Ds, their convolution is a gaussian one and not a GGX one - So we use another roughness mip mapping.
+        if (IsEnvIndexTexture2D(lightData.envIndex))
+        {
+            // Empirical remapping
+            iblMipLevel = PositivePow(preLightData.iblPerceptualRoughness[i], 0.8) * uint(max(_ColorPyramidScale.z - 1, 0));
+        }
+        else
+        {
+            iblMipLevel = PerceptualRoughnessToMipmapLevel(preLightData.iblPerceptualRoughness[i]);
+        }
+
         float4 preLD = SampleEnv(lightLoopContext, lightData.envIndex, R[i], iblMipLevel);
 
         // Used by planar reflection to discard pixel:

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/SubsurfaceScattering/SubsurfaceScatteringManager.cs

                         HDUtils.SetRenderTarget(cmd, hdCamera, m_HTile, ClearFlag.Color, CoreUtils.clearColorAllBlack);
 
                         HDUtils.SetRenderTarget(cmd, hdCamera, depthStencilBufferRT); // No need for color buffer here
-                        cmd.SetRandomWriteTarget(1, m_HTile);
+                        cmd.SetRandomWriteTarget(1, m_HTile); // This need to be done AFTER SetRenderTarget
                         // Generate HTile for the split lighting stencil usage. Don't write into stencil texture (shaderPassId = 2)
                         // Use ShaderPassID 1 => "Pass 2 - Export HTILE for stencilRef to output"
                         CoreUtils.DrawFullScreen(cmd, m_CopyStencilForSplitLighting, null, 2);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightUtilities.hlsl

-#ifndef UNITY_LIGHT_UTILITIES_INCLUDED
-#define UNITY_LIGHT_UTILITIES_INCLUDED
-
-#include "LightDefinition.cs.hlsl"
-
-// The EnvLightData of the sky light contains a bunch of compile-time constants.
-// This function sets them directly to allow the compiler to propagate them and optimize the code.
-EnvLightData InitSkyEnvLightData(int envIndex)
-{
-    EnvLightData output;
-    ZERO_INITIALIZE(EnvLightData, output);
-    output.influenceShapeType = ENVSHAPETYPE_SKY;
-    output.envIndex = envIndex;
-
-    output.influenceForward = float3(0.0, 0.0, 1.0);
-    output.influenceUp = float3(0.0, 1.0, 0.0);
-    output.influenceRight = float3(1.0, 0.0, 0.0);
-    output.influencePositionWS = float3(0.0, 0.0, 0.0);
-
-    output.weight = 1.0;
-    output.multiplier = 1.0;
-
-    // proxy
-    output.proxyForward = float3(0.0, 0.0, 1.0);
-    output.proxyUp = float3(0.0, 1.0, 0.0);
-    output.proxyRight = float3(1.0, 0.0, 0.0);
-    output.minProjectionDistance = 65504.0f;
-
-    return output;
-}
-
-#endif // UNITY_LIGHT_UTILITIES_INCLUDED

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightUtilities.hlsl.meta

-fileFormatVersion: 2
-guid: be2a44d9e57c5b943ab80fa5fc334d99
-timeCreated: 1480423337
-licenseType: Pro
-ShaderImporter:
-  defaultTextures: []
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: