Now vertex color is remapped between -1 and 1 and added to the mask map when using both at the same time for layered lit shader (instead of being multiplied)

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/LayeredLit/Editor/LayeredLitUI.cs

             public readonly GUIContent layersText = new GUIContent("Layers");
             public readonly GUIContent emissiveText = new GUIContent("Emissive");
             public readonly GUIContent layerMapMaskText = new GUIContent("Layer Mask", "Layer mask (multiplied by vertex color if enabled)");
-            public readonly GUIContent layerMapVertexColorText = new GUIContent("Use Vertex Color", "Layer mask (multiplied by layer mask if enabled)");
+            public readonly GUIContent layerMapVertexColorText = new GUIContent("Use Vertex Color", "If no layer mask is set, vertex color values between 0 and 1.0 are used as final mask.\nIf a layer mask is set, vertex color values are remapped between -1 and 1 and added to the mask (neutral at 0.5 vertex color).");
             public readonly GUIContent vertexColorHeightMultiplierText = new GUIContent("Vertex Height Scale", "Scale applied to the vertex color height.");
             public readonly GUIContent layerCountText = new GUIContent("Layer Count", "Number of layers.");
             public readonly GUIContent layerTexWorldScaleText = new GUIContent("Tiling", "Tiling factor applied to Planar/Trilinear mapping");
             bool useHeightBasedBlend = material.GetFloat(kUseHeightBasedBlend) != 0.0f;
             if(useHeightBasedBlend)
             {
-                SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR", false);
+                SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_ADD", false);
+                SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_MUL", false);
-                SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR", material.GetFloat(kLayerMaskVertexColor) != 0.0f);
+                if (material.GetTexture(kLayerMaskMap) != null)
+                {
+                    SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_ADD", material.GetFloat(kLayerMaskVertexColor) != 0.0f);
+                    SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_MUL", false);
+                }
+                else
+                {
+                    SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_MUL", material.GetFloat(kLayerMaskVertexColor) != 0.0f);
+                    SetKeyword(material, "_LAYER_MASK_VERTEX_COLOR_ADD", false);
+                }
                 SetKeyword(material, "_HEIGHT_BASED_BLEND", false);
             }
 

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         _InheritBaseLayer2("_InheritBaseLayer2", Range(0, 1.0)) = 0.0
         _InheritBaseLayer3("_InheritBaseLayer3", Range(0, 1.0)) = 0.0
 
-        _VertexColorHeightFactor("_VertexColorHeightFactor", Float) = 1.0
+        _VertexColorHeightFactor("_VertexColorHeightFactor", Float) = 0.3
 
         _DistortionVectorMap("DistortionVectorMap", 2D) = "black" {}
 
     #pragma shader_feature _EMISSIVE_COLOR_MAP
     #pragma shader_feature _HEIGHTMAP
     #pragma shader_feature _DETAIL_MAP
-    #pragma shader_feature _LAYER_MASK_VERTEX_COLOR
+    #pragma shader_feature _ _LAYER_MASK_VERTEX_COLOR_MUL _LAYER_MASK_VERTEX_COLOR_ADD
     #pragma shader_feature _HEIGHT_BASED_BLEND
     #pragma shader_feature _ _LAYEREDLIT_3_LAYERS _LAYEREDLIT_4_LAYERS
 

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/LitData.hlsl

     // Mask Values : Layer 1, 2, 3 are r, g, b
     float3 maskValues = SAMPLE_TEXTURE2D(_LayerMaskMap, sampler_LayerMaskMap, input.texCoord0).rgb;
 
-#if defined(_LAYER_MASK_VERTEX_COLOR)
+    // Mutually exclusive with _HEIGHT_BASED_BLEND
+#if defined(_LAYER_MASK_VERTEX_COLOR_MUL) // Used when no layer mask is set
+#elif defined(_LAYER_MASK_VERTEX_COLOR_ADD) // When layer mask is set, color is additive to enable user to override it.
+    maskValues = saturate(maskValues + input.vertexColor.rgb * 2.0 - 1.0);
 #endif
 
 #if defined(_HEIGHT_BASED_BLEND)