Update UI accordindly, don't touch materialId yet

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Material/LayeredLit/LayeredLitUI.cs

             }
             CoreUtils.SetKeyword(material, "_DENSITY_MODE", useDensityModeEnable);
 
-            Lit.MaterialId materialId = (Lit.MaterialId)material.GetFloat(kMaterialID);
+            LitGUI.MaterialId materialId = (LitGUI.MaterialId)material.GetFloat(kMaterialID);
-            CoreUtils.SetKeyword(material, "_MATID_SSS", materialId == Lit.MaterialId.LitSSS);
-            //CoreUtils.SetKeyword(material, "_MATID_STANDARD", materialId == Lit.MaterialId.LitStandard); // See comment in Lit.shader, it is the default, we don't define it
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_SUBSURFACE_SCATTERING", materialId == LitGUI.MaterialId.LitSSS);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_TRANSMISSION", materialId == LitGUI.MaterialId.LitSSS);
         }
         private void DoEmissiveGUI(Material material)
         {

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

             UV3
         }
 
+        public enum MaterialId
+        {
+            LitSSS          = 0,
+            LitStandard     = 1,
+            LitAniso        = 2,
+            LitClearCoat    = 3,
+            LitSpecular     = 4,
+            LitIridescence  = 5,
+        };
+
         protected MaterialProperty[] UVBase = new MaterialProperty[kMaxLayerCount];
         protected const string kUVBase = "_UVBase";
         protected MaterialProperty[] TexWorldScale = new MaterialProperty[kMaxLayerCount];
 
             m_MaterialEditor.TexturePropertySingleLine(Styles.baseColorText, baseColorMap[layerIndex], baseColor[layerIndex]);
 
-            if ((Lit.MaterialId)materialID.floatValue == Lit.MaterialId.LitStandard || (Lit.MaterialId)materialID.floatValue == Lit.MaterialId.LitAniso)
+            if ((LitGUI.MaterialId)materialID.floatValue == LitGUI.MaterialId.LitStandard || (LitGUI.MaterialId)materialID.floatValue == LitGUI.MaterialId.LitAniso)
             {
                 m_MaterialEditor.ShaderProperty(metallic[layerIndex], Styles.metallicText);
             }
                 }
             }
 
-            m_MaterialEditor.TexturePropertySingleLine(((Lit.MaterialId)materialID.floatValue == Lit.MaterialId.LitSpecular) ? Styles.maskMapSpecularText : Styles.maskMapSText, maskMap[layerIndex]);
+            m_MaterialEditor.TexturePropertySingleLine(((LitGUI.MaterialId)materialID.floatValue == LitGUI.MaterialId.LitSpecular) ? Styles.maskMapSpecularText : Styles.maskMapSText, maskMap[layerIndex]);
 
             m_MaterialEditor.ShaderProperty(normalMapSpace[layerIndex], Styles.normalMapSpaceText);
 
                 heightAmplitude[layerIndex].floatValue = (heightMax[layerIndex].floatValue - heightMin[layerIndex].floatValue) * 0.01f; // Conversion centimeters to meters.
             }
 
-            switch ((Lit.MaterialId)materialID.floatValue)
+            switch ((LitGUI.MaterialId)materialID.floatValue)
-                case Lit.MaterialId.LitSSS:
+                case LitGUI.MaterialId.LitSSS:
-                case Lit.MaterialId.LitStandard:
+                case LitGUI.MaterialId.LitStandard:
-                case Lit.MaterialId.LitAniso:
+                case LitGUI.MaterialId.LitAniso:
-                case Lit.MaterialId.LitSpecular:
+                case LitGUI.MaterialId.LitSpecular:
-                case Lit.MaterialId.LitClearCoat:
+                case LitGUI.MaterialId.LitClearCoat:
                     ShaderClearCoatInputGUI();
                     break;
                 default:
                 material.DisableKeyword("_REQUIRE_UV3");
             }
 
-            Lit.MaterialId materialId = (Lit.MaterialId)material.GetFloat(kMaterialID);
+            LitGUI.MaterialId materialId = (LitGUI.MaterialId)material.GetFloat(kMaterialID);
-            CoreUtils.SetKeyword(material, "_MATID_SSS", materialId == Lit.MaterialId.LitSSS);
-            //CoreUtils.SetKeyword(material, "_MATID_STANDARD", materialId == Lit.MaterialId.LitStandard); // See comment in Lit.shader, it is the default, we don't define it
-            CoreUtils.SetKeyword(material, "_MATID_ANISO", materialId == Lit.MaterialId.LitAniso);
-            CoreUtils.SetKeyword(material, "_MATID_SPECULAR", materialId == Lit.MaterialId.LitSpecular);
-            CoreUtils.SetKeyword(material, "_MATID_CLEARCOAT", materialId == Lit.MaterialId.LitClearCoat);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_SUBSURFACE_SCATTERING", materialId == LitGUI.MaterialId.LitSSS);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_TRANSMISSION", materialId == LitGUI.MaterialId.LitSSS);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_ANISOTROPY", materialId == LitGUI.MaterialId.LitAniso);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_CLEAR_COAT", materialId == LitGUI.MaterialId.LitClearCoat);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_IRIDESCENCE", materialId == LitGUI.MaterialId.LitIridescence);
+            CoreUtils.SetKeyword(material, "_MATERIAL_FEATURE_SPECULAR_COLOR", materialId == LitGUI.MaterialId.LitSpecular);
 
             var refractionModeValue = (Lit.RefractionMode)material.GetFloat(kRefractionMode);
             // We can't have refraction in pre-refraction queue

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLit.shader

         [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
-        [Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1 // MaterialId.RegularLighting
+        [Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1
 
         [Enum(None, 0, Vertex displacement, 1, Pixel displacement, 2)] _DisplacementMode("DisplacementMode", Int) = 0
         [ToggleOff] _DisplacementLockObjectScale("displacement lock object scale", Float) = 1.0
     #pragma shader_feature _BLENDMODE_PRESERVE_SPECULAR_LIGHTING
     #pragma shader_feature _ENABLE_FOG_ON_TRANSPARENT
 
-    // MaterialId are used as shader feature to allow compiler to optimize properly
-    // Note _MATID_STANDARD is not define as there is always the default case "_". We assign default as _MATID_STANDARD, so we never test _MATID_STANDARD
-    #pragma shader_feature _ _MATID_SSS
+    // MaterialFeature are used as shader feature to allow compiler to optimize properly
+    #pragma shader_feature _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
+    #pragma shader_feature _MATERIAL_FEATURE_TRANSMISSION
 
     // enable dithering LOD crossfade
     #pragma multi_compile _ LOD_FADE_CROSSFADE
     #define HAVE_VERTEX_MODIFICATION
 
     // If we use subsurface scattering, enable output split lighting (for forward pass)
-    #if defined(_MATID_SSS) && !defined(_SURFACE_TYPE_TRANSPARENT)
+    #if defined(_MATERIAL_FEATURE_SUBSURFACE_SCATTERING) && !defined(_SURFACE_TYPE_TRANSPARENT)
     #define OUTPUT_SPLIT_LIGHTING
     #endif
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLitData.hlsl

     surfaceData.thickness = SURFACEDATA_BLEND_SCALAR(surfaceData, thickness, weights);
     surfaceData.diffusionProfile = SURFACEDATA_BLEND_SSS_PROFILE(surfaceData, diffusionProfile, weights);
 
-    // Layered shader support either SSS or standard (can't mix them)
-#ifdef _MATID_SSS
-    surfaceData.materialId = MATERIALID_LIT_SSS;
-#else // Default
-    surfaceData.materialId = MATERIALID_LIT_STANDARD;
+    // Layered shader support SSS and Transmission features
+    surfaceData.enableSubsurfaceScattering  = false;
+    surfaceData.enableTransmission          = false;
+    surfaceData.enableAnisotropy            = false;
+    surfaceData.enableClearCoat             = false;
+    surfaceData.enableIridescence           = false;
+    surfaceData.enableSpecularColor         = false;
+
+#ifdef _MATERIALFEATURE_SUBSURFACE_SCATTERING
+    surfaceData.enableSubsurfaceScattering  = true;
+#endif
+#ifdef _MATERIAL_FEATURE_TRANSMISSION
+    surfaceData.enableTransmission          = true;
 #endif
 
     // Init other parameters

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLitTessellation.shader

         [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
-    	[Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1 // MaterialId.RegularLighting
+        [Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1
         [Enum(None, 0, Tessellation displacement, 3)] _DisplacementMode("DisplacementMode", Int) = 3
         [ToggleOff] _DisplacementLockObjectScale("displacement lock object scale", Float) = 1.0
         [ToggleOff] _DisplacementLockTilingScale("displacement lock tiling scale", Float) = 1.0
     #pragma shader_feature _BLENDMODE_PRESERVE_SPECULAR_LIGHTING
     #pragma shader_feature _ENABLE_FOG_ON_TRANSPARENT
 
-    // MaterialId are used as shader feature to allow compiler to optimize properly
-    // Note _MATID_STANDARD is not define as there is always the default case "_". We assign default as _MATID_STANDARD, so we never test _MATID_STANDARD
-    #pragma shader_feature _ _MATID_SSS
+    // MaterialFeature are used as shader feature to allow compiler to optimize properly
+    #pragma shader_feature _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
+    #pragma shader_feature _MATERIAL_FEATURE_TRANSMISSION
 
     // enable dithering LOD crossfade
     #pragma multi_compile _ LOD_FADE_CROSSFADE
     #define HAVE_TESSELLATION_MODIFICATION
 
     // If we use subsurface scattering, enable output split lighting (for forward pass)
-    #if defined(_MATID_SSS) && !defined(_SURFACE_TYPE_TRANSPARENT)
+    #if defined(_MATERIAL_FEATURE_SUBSURFACE_SCATTERING) && !defined(_SURFACE_TYPE_TRANSPARENT)
     #define OUTPUT_SPLIT_LIGHTING
     #endif
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/Lit.shader

     #pragma shader_feature _BLENDMODE_PRESERVE_SPECULAR_LIGHTING
     #pragma shader_feature _ENABLE_FOG_ON_TRANSPARENT
 
-    // MaterialId are used as shader feature to allow compiler to optimize properly
-    // Note _MATID_STANDARD is not define as there is always the default case "_". We assign default as _MATID_STANDARD, so we never test _MATID_STANDARD
-    #pragma shader_feature _ _MATID_SSS _MATID_ANISO _MATID_SPECULAR _MATID_CLEARCOAT
+    // MaterialFeature are used as shader feature to allow compiler to optimize properly
+    #pragma shader_feature _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
+    #pragma shader_feature _MATERIAL_FEATURE_TRANSMISSION
+    #pragma shader_feature _MATERIAL_FEATURE_ANISOTROPY
+    #pragma shader_feature _MATERIAL_FEATURE_CLEAR_COAT
+    #pragma shader_feature _MATERIAL_FEATURE_IRIDESCENCE
+    #pragma shader_feature _MATERIAL_FEATURE_SPECULAR_COLOR
 
     // enable dithering LOD crossfade
     #pragma multi_compile _ LOD_FADE_CROSSFADE
     #define HAVE_VERTEX_MODIFICATION
 
     // If we use subsurface scattering, enable output split lighting (for forward pass)
-    #if defined(_MATID_SSS) && !defined(_SURFACE_TYPE_TRANSPARENT)
+    #if defined(_MATERIAL_FEATURE_SUBSURFACE_SCATTERING) && !defined(_SURFACE_TYPE_TRANSPARENT)
     #define OUTPUT_SPLIT_LIGHTING
     #endif
 

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

     // This part of the code is not used in case of layered shader but we keep the same macro system for simplicity
 #if !defined(LAYERED_LIT_SHADER)
 
-    // Having individual shader features for each materialID like this allow the compiler to optimize
-#ifdef _MATID_SSS
-    surfaceData.materialId = MATERIALID_LIT_SSS;
-#elif defined(_MATID_ANISO)
-    surfaceData.materialId = MATERIALID_LIT_ANISO;
-#elif defined(_MATID_SPECULAR)
-    surfaceData.materialId = MATERIALID_LIT_SPECULAR;
-#elif defined(_MATID_CLEARCOAT)
-    surfaceData.materialId = MATERIALID_LIT_CLEAR_COAT;
-#else // Default
-    surfaceData.materialId = MATERIALID_LIT_STANDARD;
+    // These static material feature allow compile time optimization
+    surfaceData.enableSubsurfaceScattering  = false;
+    surfaceData.enableTransmission          = false;
+    surfaceData.enableAnisotropy            = false;
+    surfaceData.enableClearCoat             = false;
+    surfaceData.enableIridescence           = false;
+    surfaceData.enableSpecularColor         = false;
+
+#ifdef _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
+    surfaceData.enableSubsurfaceScattering  = true;
+#endif
+#ifdef _MATERIAL_FEATURE_TRANSMISSION
+    surfaceData.enableTransmission          = true;
+#endif
+#ifdef _MATERIAL_FEATURE_ANISOTROPY
+    surfaceData.enableAnisotropy            = true;
+#endif
+#ifdef _MATERIAL_FEATURE_CLEAR_COAT
+    surfaceData.enableClearCoat             = true;
+#endif
+#ifdef _MATERIAL_FEATURE_IRIDESCENCE
+    surfaceData.enableIridescence           = true;
+#endif
+#ifdef _MATERIAL_FEATURE_SPECULAR_COLOR
+    surfaceData.enableSpecularColor         = true;
 #endif
 
 #ifdef _TANGENTMAP
 
     // Mandatory to setup value to keep compiler quiet
 
-    // Layered shader only supports the standard material
-    surfaceData.materialId = MATERIALID_LIT_STANDARD;
+    // Layered shader material feature are define outside of this call
+    surfaceData.enableSubsurfaceScattering  = false;
+    surfaceData.enableTransmission          = false;
+    surfaceData.enableAnisotropy            = false;
+    surfaceData.enableClearCoat             = false;
+    surfaceData.enableIridescence           = false;
+    surfaceData.enableSpecularColor         = false;
 
     // All these parameters are ignore as they are re-setup outside of the layers function
     // Note: any parameters set here must also be set in GetSurfaceAndBuiltinData() layer version

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/LitTessellation.shader

     #pragma shader_feature _BLENDMODE_PRESERVE_SPECULAR_LIGHTING
     #pragma shader_feature _ENABLE_FOG_ON_TRANSPARENT
 
-    // MaterialId are used as shader feature to allow compiler to optimize properly
-    // Note _MATID_STANDARD is not define as there is always the default case "_". We assign default as _MATID_STANDARD, so we never test _MATID_STANDARD
-    #pragma shader_feature _ _MATID_SSS _MATID_ANISO _MATID_SPECULAR _MATID_CLEARCOAT
+    // MaterialFeature are used as shader feature to allow compiler to optimize properly
+    #pragma shader_feature _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
+    #pragma shader_feature _MATERIAL_FEATURE_TRANSMISSION
+    #pragma shader_feature _MATERIAL_FEATURE_ANISOTROPY
+    #pragma shader_feature _MATERIAL_FEATURE_CLEAR_COAT
+    #pragma shader_feature _MATERIAL_FEATURE_IRIDESCENCE
+    #pragma shader_feature _MATERIAL_FEATURE_SPECULAR_COLOR
 
     // enable dithering LOD crossfade
     #pragma multi_compile _ LOD_FADE_CROSSFADE
     #define HAVE_TESSELLATION_MODIFICATION
 
     // If we use subsurface scattering, enable output split lighting (for forward pass)
-    #if defined(_MATID_SSS) && !defined(_SURFACE_TYPE_TRANSPARENT)
+    #if defined(_MATERIAL_FEATURE_SUBSURFACE_SCATTERING) && !defined(_SURFACE_TYPE_TRANSPARENT)
     #define OUTPUT_SPLIT_LIGHTING
     #endif