Add a thickness remap for the thickness map (on the material itself)

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         _ThicknessMap2("Thickness Map", 2D) = "white" {}
         _ThicknessMap3("Thickness Map", 2D) = "white" {}
 
+        _ThicknessRemap0("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap1("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap2("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap3("Thickness Remap", Vector) = (0, 1, 0, 0)
+
         // All the following properties exist only in layered lit material
 
         // Layer blending options

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

         _ThicknessMap2("Thickness Map", 2D) = "white" {}
         _ThicknessMap3("Thickness Map", 2D) = "white" {}
 
+        _ThicknessRemap0("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap1("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap2("Thickness Remap", Vector) = (0, 1, 0, 0)
+        _ThicknessRemap3("Thickness Remap", Vector) = (0, 1, 0, 0)
+
         // All the following properties exist only in layered lit material
 
         // Layer blending options

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

             public static GUIContent subsurfaceRadiusMapText = new GUIContent("Subsurface radius map (R)", "Determines the range of the blur.");
             public static GUIContent thicknessText = new GUIContent("Thickness", "If subsurface scattering is enabled, low values allow some light to be transmitted through the object.");
             public static GUIContent thicknessMapText = new GUIContent("Thickness map (R)", "If subsurface scattering is enabled, low values allow some light to be transmitted through the object.");
+            public static GUIContent thicknessRemapText = new GUIContent("Thickness Remap", "Remaps values of the thickness map from [0, 1] to the specified range.");
 
             // Clear Coat
             public static GUIContent coatCoverageText = new GUIContent("Coat Coverage", "Percentage of clear coat coverage");
         protected const string kThickness = "_Thickness";
         protected MaterialProperty[] thicknessMap = new MaterialProperty[kMaxLayerCount];
         protected const string kThicknessMap = "_ThicknessMap";
+        protected MaterialProperty[] thicknessRemap = new MaterialProperty[kMaxLayerCount];
+        protected const string kThicknessRemap = "_ThicknessRemap";
 
         protected MaterialProperty[] UVDetail = new MaterialProperty[kMaxLayerCount];
         protected const string kUVDetail = "_UVDetail";
                 subsurfaceRadiusMap[i] = FindProperty(string.Format("{0}{1}", kSubsurfaceRadiusMap, m_PropertySuffixes[i]), props);
                 thickness[i] = FindProperty(string.Format("{0}{1}", kThickness, m_PropertySuffixes[i]), props);
                 thicknessMap[i] = FindProperty(string.Format("{0}{1}", kThicknessMap, m_PropertySuffixes[i]), props);
+                thicknessRemap[i] = FindProperty(string.Format("{0}{1}", kThicknessRemap, m_PropertySuffixes[i]), props);
 
                 // Details
                 UVDetail[i] = FindProperty(string.Format("{0}{1}", kUVDetail, m_PropertySuffixes[i]), props);
 
             m_MaterialEditor.ShaderProperty(subsurfaceRadius[layerIndex], Styles.subsurfaceRadiusText);
             m_MaterialEditor.TexturePropertySingleLine(Styles.subsurfaceRadiusMapText, subsurfaceRadiusMap[layerIndex]);
-            m_MaterialEditor.ShaderProperty(thickness[layerIndex], Styles.thicknessText);
+            if (thicknessMap[layerIndex].textureValue != null)
+            {
+                // Display the remap of texture values.
+                Vector2 remap = thicknessRemap[layerIndex].vectorValue;
+                EditorGUI.BeginChangeCheck();
+                EditorGUILayout.MinMaxSlider(Styles.thicknessRemapText, ref remap.x, ref remap.y, 0.0f, 1.0f);
+                if (EditorGUI.EndChangeCheck())
+                {
+                    thicknessRemap[layerIndex].vectorValue = remap;
+                }
+            }
+            else
+            {
+                // Allow the user to set the constant value of thickness if no thickness map is provided.
+                m_MaterialEditor.ShaderProperty(thickness[layerIndex], Styles.thicknessText);
+            }
         }
 
         protected void ShaderClearCoatInputGUI()

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.shader

         _SubsurfaceRadiusMap("Subsurface Radius Map", 2D) = "white" {}
         _Thickness("Thickness", Range(0.0, 1.0)) = 1.0
         _ThicknessMap("Thickness Map", 2D) = "white" {}
+        _ThicknessRemap("Thickness Remap", Vector) = (0, 1, 0, 0)
 
         _CoatCoverage("Coat Coverage", Range(0.0, 1.0)) = 1.0
         _CoatIOR("Coat IOR", Range(0.0, 1.0)) = 0.5

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitDataIndividualLayer.hlsl

 
     surfaceData.subsurfaceProfile = ADD_IDX(_SubsurfaceProfile);
     surfaceData.subsurfaceRadius = ADD_IDX(_SubsurfaceRadius);
-    surfaceData.thickness = ADD_IDX(_Thickness);
 
 #ifdef _SUBSURFACE_RADIUS_MAP_IDX
     surfaceData.subsurfaceRadius *= SAMPLE_UVMAPPING_TEXTURE2D(ADD_IDX(_SubsurfaceRadiusMap), SAMPLER_SUBSURFACE_RADIUSMAP_IDX, ADD_IDX(layerTexCoord.base)).r;
-    surfaceData.thickness *= SAMPLE_UVMAPPING_TEXTURE2D(ADD_IDX(_ThicknessMap), SAMPLER_THICKNESSMAP_IDX, ADD_IDX(layerTexCoord.base)).r;
+    surfaceData.thickness = SAMPLE_UVMAPPING_TEXTURE2D(ADD_IDX(_ThicknessMap), SAMPLER_THICKNESSMAP_IDX, ADD_IDX(layerTexCoord.base)).r;
+    surfaceData.thickness = ADD_IDX(_ThicknessRemap).x + ADD_IDX(_ThicknessRemap).y * surfaceData.thickness;
+#else
+    surfaceData.thickness = ADD_IDX(_Thickness);
 #endif
 
     // This part of the code is not used in case of layered shader but we keep the same macro system for simplicity

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitProperties.hlsl

 int   _SubsurfaceProfile;
 float _SubsurfaceRadius;
 float _Thickness;
+float4 _ThicknessRemap;
 
 float _CoatCoverage;
 float _CoatIOR;

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitTessellation.shader

         _SubsurfaceRadiusMap("Subsurface Radius Map", 2D) = "white" {}
         _Thickness("Thickness", Range(0.0, 1.0)) = 1.0
         _ThicknessMap("Thickness Map", 2D) = "white" {}
+        _ThicknessRemap("Thickness Remap", Vector) = (0, 1, 0, 0)
 
         _CoatCoverage("Coat Coverage", Range(0.0, 1.0)) = 1.0
         _CoatIOR("Coat IOR", Range(0.0, 1.0)) = 0.5

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/SubsurfaceScatteringSettings.cs

             ValidateArray(ref halfRcpVariancesAndWeights, SssConstants.SSS_N_PROFILES * 2);
             ValidateArray(ref filterKernelsBasic,         SssConstants.SSS_N_PROFILES * SssConstants.SSS_BASIC_N_SAMPLES);
 
-            Debug.Assert(SssConstants.SSS_NEUTRAL_PROFILE_ID < 16, "Transmission flags (32-bit integer) cannot support more than 16 profiles.");
+            Debug.Assert(SssConstants.SSS_NEUTRAL_PROFILE_ID < 16, "Transmission flags (32-bit integer) cannot support more than 16 profiles (2 bits per profile).");
 
             UpdateCache();
         }