Unity Shader 灰度Shader(支持UGUI Mask裁剪)

shader源碼如下 其中支持mask裁剪部分（註意 有兩處地方需要添加）的代碼同樣適合其他自定義shader

Shader "Custom/UISprite" {
    Properties
    {
       _MainTex("Base (RGB), Alpha (A)", 2D) = "white" {}

    //支持Mask 裁剪的部分
    //Start
    _StencilComp("Stencil Comparison", Float) = 8
    _Stencil("Stencil ID", Float) = 0
    _StencilOp("Stencil Operation", Float) = 0
    _StencilWriteMask("Stencil Write Mask", Float) = 255
    _StencilReadMask("Stencil Read Mask", Float) = 255
    _ColorMask("Color Mask", Float) = 15
    //End
    }

        SubShader
    {
     LOD 200
     Tags
     {
      "Queue" = "Transparent"
      "IgnoreProjector" = "True"
      "RenderType" = "Transparent"
     }
    //支持Mask 裁剪的部分
    //Start
     Stencil
     {
       Ref[_Stencil]
       Comp[_StencilComp]
       Pass[_StencilOp]
       ReadMask[_StencilReadMask]
       WriteMask[_StencilWriteMask]
     }
     ColorMask[_ColorMask]
     //End
     Pass
     {
      Cull Off
      Lighting Off
      ZWrite Off
      Fog { Mode Off }
      ColorMask RGB
      AlphaTest Greater .01
      Blend SrcAlpha OneMinusSrcAlpha
      ColorMaterial AmbientAndDiffuse

      CGPROGRAM
      #pragma vertex vert
      #pragma fragment frag
      #include "UnityCG.cginc"
      sampler2D _MainTex;
      struct appdata_t
      {
       float4 vertex : POSITION;
       half4 color : COLOR;
       float2 texcoord : TEXCOORD0;
      };
      struct v2f
      {
       float4 vertex : POSITION;
       half4 color : COLOR;
       float2 texcoord : TEXCOORD0;
      };
      v2f vert(appdata_t v)
      {
       v2f o;
       o.vertex = UnityObjectToClipPos(v.vertex);
       o.color = v.color;
       o.texcoord = v.texcoord;
       return o;
      }
      half4 frag(v2f IN) : COLOR
      {
          half4 col = tex2D(_MainTex, IN.texcoord) * IN.color;
          float c = 0.299*col.r + 0.587*col.g + 0.184*col.b;
          col.r = col.g = col.b = c;
          return col;
         }
         ENDCG
        }
    }
}
 

！！註意：

支持Mask後在Mask物體下，Image的Material的屬性只有第一次賦值時有效，無法動態修改，如果有需求就要新建一個腳本繼承Image並重寫GetModifiedMaterial方法。

重寫代碼如下

public class CustomImage : Image
 {
     public override Material GetModifiedMaterial(Material baseMaterial)
     {
         Material cModifiedMat = base.GetModifiedMaterial(baseMaterial);
         return cModifiedMat;
     }
 }
 

Unity Shader 灰度Shader(支持UGUI Mask裁剪)