Remove uvmapping for blend mask because terrain always uses uv0.

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

         {
             public readonly GUIContent layersText = new GUIContent("Inputs");
             public readonly GUIContent layerMapMaskText = new GUIContent("Layer Mask", "Layer mask");
-
-            public readonly GUIContent layerTexWorldScaleText = new GUIContent("World Scale", "Tiling factor applied to Planar/Trilinear mapping");
-            public readonly GUIContent UVBlendMaskText = new GUIContent("BlendMask UV Mapping", "Base UV Mapping mode of the layer.");
-
-            public readonly GUIContent useMainLayerInfluenceModeText = new GUIContent("Main Layer Influence", "Switch between regular layers mode and base/layers mode");
-
             public readonly GUIContent heightTransition = new GUIContent("Height Transition", "Size in world units of the smooth transition between layers.");
         }
 
         }
 
         // Layer options
-        MaterialProperty UVBlendMask = null;
-        const string kUVBlendMask = "_UVBlendMask";
-        MaterialProperty UVMappingMaskBlendMask = null;
-        const string kUVMappingMaskBlendMask = "_UVMappingMaskBlendMask";
-        MaterialProperty texWorldScaleBlendMask = null;
-        const string kTexWorldScaleBlendMask = "_TexWorldScaleBlendMask";
         MaterialProperty useHeightBasedBlend = null;
         const string kUseHeightBasedBlend = "_UseHeightBasedBlend";
 
 
         protected override void FindMaterialProperties(MaterialProperty[] props)
         {
-            UVBlendMask = FindProperty(kUVBlendMask, props);
-            UVMappingMaskBlendMask = FindProperty(kUVMappingMaskBlendMask, props);
-            texWorldScaleBlendMask = FindProperty(kTexWorldScaleBlendMask, props);
-
             useHeightBasedBlend = FindProperty(kUseHeightBasedBlend, props);
             heightTransition = FindProperty(kHeightTransition, props);
 
             EditorGUI.indentLevel++;
             GUILayout.Label(styles.layersText, EditorStyles.boldLabel);
 
-            EditorGUI.indentLevel++;
-            m_MaterialEditor.ShaderProperty(UVBlendMask, styles.UVBlendMaskText);
-            UVBaseMapping uvBlendMask = (UVBaseMapping)UVBlendMask.floatValue;
-
-            float X, Y, Z, W;
-            X = (uvBlendMask == UVBaseMapping.UV0) ? 1.0f : 0.0f;
-            Y = (uvBlendMask == UVBaseMapping.UV1) ? 1.0f : 0.0f;
-            Z = (uvBlendMask == UVBaseMapping.UV2) ? 1.0f : 0.0f;
-            W = (uvBlendMask == UVBaseMapping.UV3) ? 1.0f : 0.0f;
-
-            UVMappingMaskBlendMask.colorValue = new Color(X, Y, Z, W);
-
-            if (((UVBaseMapping)UVBlendMask.floatValue == UVBaseMapping.Planar) ||
-                ((UVBaseMapping)UVBlendMask.floatValue == UVBaseMapping.Triplanar))
-            {
-                m_MaterialEditor.ShaderProperty(texWorldScaleBlendMask, styles.layerTexWorldScaleText);
-            }
-            EditorGUI.indentLevel--;
-
             EditorGUI.BeginChangeCheck();
             EditorGUI.showMixedValue = useHeightBasedBlend.hasMixedValue;
             m_UseHeightBasedBlend = EditorGUILayout.Toggle(styles.useHeightBasedBlendText, useHeightBasedBlend.floatValue > 0.0f);
 
         static public void SetupLayersMappingKeywords(Material material)
         {
-            // Blend mask
-            UVBaseMapping UVBlendMaskMapping = (UVBaseMapping)material.GetFloat(kUVBlendMask);
-            CoreUtils.SetKeyword(material, "_LAYER_MAPPING_PLANAR_BLENDMASK", UVBlendMaskMapping == UVBaseMapping.Planar);
-            CoreUtils.SetKeyword(material, "_LAYER_MAPPING_TRIPLANAR_BLENDMASK", UVBlendMaskMapping == UVBaseMapping.Triplanar);
-
             const string kLayerMappingPlanar = "_LAYER_MAPPING_PLANAR";
             const string kLayerMappingTriplanar = "_LAYER_MAPPING_TRIPLANAR";
 

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

         _InheritBaseColor2("_InheritBaseColor2", Range(0, 1.0)) = 0.0
         _InheritBaseColor3("_InheritBaseColor3", Range(0, 1.0)) = 0.0
 
-        [Enum(UV0, 0, UV1, 1, UV2, 2, UV3, 3, Planar, 4, Triplanar, 5)] _UVBlendMask("UV Set for blendMask", Float) = 0
-        [HideInInspector] _UVMappingMaskBlendMask("_UVMappingMaskBlendMask", Color) = (1, 0, 0, 0)
-        _TexWorldScaleBlendMask("Tiling", Float) = 1.0
-
         // Following are builtin properties
 
         [ToggleUI]  _EnableSpecularOcclusion("Enable specular occlusion", Float) = 0.0
 
     #pragma shader_feature _DOUBLESIDED_ON
 
-    //#pragma shader_feature _ _LAYER_MAPPING_PLANAR_BLENDMASK _LAYER_MAPPING_TRIPLANAR_BLENDMASK
     //#pragma shader_feature _ _LAYER_MAPPING_PLANAR0 _LAYER_MAPPING_TRIPLANAR0
     //#pragma shader_feature _ _LAYER_MAPPING_PLANAR1 _LAYER_MAPPING_TRIPLANAR1
     //#pragma shader_feature _ _LAYER_MAPPING_PLANAR2 _LAYER_MAPPING_TRIPLANAR2

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

     layerTexCoord.vertexNormalWS = vertexNormalWS;
     layerTexCoord.triplanarWeights = ComputeTriplanarWeights(vertexNormalWS);
 
-    int mappingType = UV_MAPPING_UVSET;
-#if defined(_LAYER_MAPPING_PLANAR_BLENDMASK)
-    mappingType = UV_MAPPING_PLANAR;
-#elif defined(_LAYER_MAPPING_TRIPLANAR_BLENDMASK)
-    mappingType = UV_MAPPING_TRIPLANAR;
-#endif
-
-    ComputeLayerTexCoord0(  texCoord0, texCoord1, texCoord2, texCoord3, _UVMappingMaskBlendMask, _UVMappingMaskBlendMask,
+    ComputeLayerTexCoord0(  texCoord0, texCoord1, texCoord2, texCoord3, float4(1, 0, 0, 0), float4(0, 0, 0, 0),
-                            positionWS, _TexWorldScaleBlendMask,
-                            mappingType, layerTexCoord);
+                            positionWS, 1,
+                            UV_MAPPING_UVSET, layerTexCoord);
 
     layerTexCoord.blendMask = layerTexCoord.base0;
 
 
-    mappingType = UV_MAPPING_UVSET;
+    int mappingType = UV_MAPPING_UVSET;
 #if defined(_LAYER_MAPPING_PLANAR0)
     mappingType = UV_MAPPING_PLANAR;
 #elif defined(_LAYER_MAPPING_TRIPLANAR0)