Add clearCoat option in Lit target to be able to disable it.

com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/HDLitData.cs

@@ -66,5 +66,13 @@ public bool energyConservingSpecular
             get => m_EnergyConservingSpecular;
             set => m_EnergyConservingSpecular = value;
         }
+
+        [SerializeField]
+        bool m_ClearCoat = false;
+        public bool clearCoat
+        {
+            get => m_ClearCoat;
+            set => m_ClearCoat = value;
+        }
     }
 }

com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/HDLitSubTarget.Migration.cs

@@ -49,6 +49,7 @@ void UpgradePBRMasterNode(PBRMasterNode1 pbrMasterNode, out Dictionary<BlockFiel
             lightingData.receiveSSRTransparent = false;
             litData.materialType = pbrMasterNode.m_Model == PBRMasterNode1.Model.Specular ? HDLitData.MaterialType.SpecularColor : HDLitData.MaterialType.Standard;
             litData.energyConservingSpecular = false;
+            litData.clearCoat = false;
             target.customEditorGUI = pbrMasterNode.m_OverrideEnabled ? pbrMasterNode.m_ShaderGUIOverride : "";
             systemData.TryChangeRenderingPass(systemData.renderingPass);
             // Handle mapping of Normal block specifically
@@ -137,6 +138,7 @@ void UpgradeHDLitMasterNode(HDLitMasterNode1 hdLitMasterNode, out Dictionary<Blo
             HDLitData.MaterialType materialType = (HDLitData.MaterialType)hdLitMasterNode.m_MaterialType;
             lightingData.subsurfaceScattering = materialType == HDLitData.MaterialType.SubsurfaceScattering;
 
+            litData.clearCoat = UpgradeCoatMask(hdLitMasterNode);
             litData.energyConservingSpecular = hdLitMasterNode.m_EnergyConservingSpecular;
             litData.rayTracing = hdLitMasterNode.m_RayTracing;
             litData.refractionModel = hdLitMasterNode.m_RefractionModel; 
@@ -209,6 +211,19 @@ bool AdditionalSlotMaskTests(HDLitMasterNode1.SlotMask slotMask)
                 }
             }
 
+            bool UpgradeCoatMask(HDLitMasterNode1 masterNode)
+            {
+                var coatMaskSlotId = HDLitMasterNode1.CoatMaskSlotId;
+
+                var node = masterNode as AbstractMaterialNode;
+                var coatMaskSlot = node.FindSlot<Vector1MaterialSlot>(coatMaskSlotId);
+                if(coatMaskSlot == null)
+                    return false;
+
+                coatMaskSlot.owner = node;
+                return (coatMaskSlot.isConnected || coatMaskSlot.value > 0.0f);
+            }
+
             // Set blockmap
             blockMap = new Dictionary<BlockFieldDescriptor, int>();
 

com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/HDLitSubTarget.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;
@@ -84,7 +84,8 @@ public override void GetFields(ref TargetFieldContext context)
             // Misc
 
             context.AddField(HDFields.EnergyConservingSpecular,             litData.energyConservingSpecular);
-            context.AddField(HDFields.CoatMask,                             context.blocks.Contains(HDBlockFields.SurfaceDescription.CoatMask) && context.pass.validPixelBlocks.Contains(HDBlockFields.SurfaceDescription.CoatMask));
+            context.AddField(HDFields.CoatMask,                             context.blocks.Contains(HDBlockFields.SurfaceDescription.CoatMask) && context.pass.validPixelBlocks.Contains(HDBlockFields.SurfaceDescription.CoatMask) && litData.clearCoat);
+            context.AddField(HDFields.ClearCoat,                            litData.clearCoat); // Enable clear coat material feature
             context.AddField(HDFields.Tangent,                              context.blocks.Contains(HDBlockFields.SurfaceDescription.Tangent) && context.pass.validPixelBlocks.Contains(HDBlockFields.SurfaceDescription.Tangent));
             context.AddField(HDFields.RayTracing,                           litData.rayTracing);
         }
@@ -99,7 +100,7 @@ public override void GetActiveBlocks(ref TargetActiveBlockContext context)
             AddDistortionBlocks(ref context);
 
             // Common
-            context.AddBlock(HDBlockFields.SurfaceDescription.CoatMask);
+            context.AddBlock(HDBlockFields.SurfaceDescription.CoatMask,             litData.clearCoat);
 
             // Refraction
             context.AddBlock(HDBlockFields.SurfaceDescription.RefractionIndex,      hasRefraction);

com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/LitPass.template

@@ -30,6 +30,7 @@ Pass
     $Material.Anisotropy:               #define _MATERIAL_FEATURE_ANISOTROPY 1
     $Material.Iridescence:              #define _MATERIAL_FEATURE_IRIDESCENCE 1
     $Material.SpecularColor:            #define _MATERIAL_FEATURE_SPECULAR_COLOR 1
+    $Material.ClearCoat:                #define _MATERIAL_FEATURE_CLEAR_COAT
     $AmbientOcclusion:                  #define _AMBIENT_OCCLUSION 1
     $SpecularOcclusionFromAO:           #define _SPECULAR_OCCLUSION_FROM_AO 1
     $SpecularOcclusionFromAOBentNormal: #define _SPECULAR_OCCLUSION_FROM_AO_BENT_NORMAL 1
@@ -207,7 +208,9 @@ Pass
             surfaceData.materialFeatures |= MATERIALFEATUREFLAGS_LIT_SPECULAR_COLOR;
         #endif
 
-        $CoatMask: surfaceData.materialFeatures |= MATERIALFEATUREFLAGS_LIT_CLEAR_COAT;
+        #ifdef _MATERIAL_FEATURE_CLEAR_COAT
+            surfaceData.materialFeatures |= MATERIALFEATUREFLAGS_LIT_CLEAR_COAT;
+        #endif
 
         #if defined (_MATERIAL_FEATURE_SPECULAR_COLOR) && defined (_ENERGY_CONSERVING_SPECULAR)
             // Require to have setup baseColor

com.unity.render-pipelines.high-definition/Editor/Material/Lit/ShaderGraph/LitSurfaceOptionPropertyBlock.cs

@@ -17,6 +17,11 @@ namespace UnityEditor.Rendering.HighDefinition.ShaderGraph
     class LitSurfaceOptionPropertyBlock : SurfaceOptionPropertyBlock
     {
         HDLitData litData;
+
+        class Styles
+        {
+            public static GUIContent enableClearCoat = new GUIContent("Clear Coat", "Enable Clear Coat");
+        }
 
         public LitSurfaceOptionPropertyBlock(SurfaceOptionPropertyBlock.Features features, HDLitData litData) : base(features)
             => this.litData = litData;
@@ -34,6 +39,7 @@ protected override void CreatePropertyGUI()
 
             base.CreatePropertyGUI();
 
+            AddProperty(Styles.enableClearCoat, () => litData.clearCoat, (newValue) => litData.clearCoat = newValue);
             AddProperty(transmissionEnableText, () => litData.sssTransmission, (newValue) => litData.sssTransmission = newValue);
             AddProperty(refractionModelText, () => litData.refractionModel, (newValue) => litData.refractionModel = newValue);
             AddProperty(energyConservingSpecularColorText, () => litData.energyConservingSpecular, (newValue) => litData.energyConservingSpecular = newValue);

com.unity.render-pipelines.high-definition/Editor/ShaderGraph/HDFields.cs

@@ -32,6 +32,7 @@ static class HDFields
         public static FieldDescriptor Transmission =            new FieldDescriptor(kMaterial, "Transmission", "_MATERIAL_FEATURE_TRANSMISSION 1");
         public static FieldDescriptor Translucent =             new FieldDescriptor(kMaterial, "Translucent", "_MATERIAL_FEATURE_TRANSLUCENT 1");
         public static FieldDescriptor Coat =                    new FieldDescriptor(kMaterial, "Coat", "_MATERIAL_FEATURE_COAT");
+        public static FieldDescriptor ClearCoat =               new FieldDescriptor(kMaterial, "ClearCoat", "_MATERIAL_FEATURE_CLEAR_COAT");
         public static FieldDescriptor CoatNormal =              new FieldDescriptor(kMaterial, "CoatNormal", "_MATERIAL_FEATURE_COAT_NORMALMAP");
         public static FieldDescriptor DualSpecularLobe =        new FieldDescriptor(kMaterial, "DualSpecularLobe", "_MATERIAL_FEATURE_DUAL_SPECULAR_LOBE");
         public static FieldDescriptor Eye =                     new FieldDescriptor(kMaterial, "Eye", "_MATERIAL_FEATURE_EYE 1");