解决灰色shader与mask冲突的方案

Shader "Custom/Opaque"
  {  
     Properties
     {
         [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
         _Color ("Tint", Color) = (1,1,1,1)
         
         // required for UI.Mask
         _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
     }
     SubShader
     {
         Tags 
         { 
             // ...
         }
         
         // required for UI.Mask
         Stencil
         {
             Ref [_Stencil]
             Comp [_StencilComp]
             Pass [_StencilOp] 
             ReadMask [_StencilReadMask]
             WriteMask [_StencilWriteMask]
         }
          ColorMask [_ColorMask]
         
         Pass
         {
             // ...
         }
     }
  }

9~14行以及24~32行是解决的方案

完整：

Shader "UI/Default Gray"
{
    Properties
    {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Tint", Color) = (1,1,1,1)
        _MyColor("MyColor", Color) = (1,1,1,1)

            // required for UI.Mask
            _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
    }

    SubShader
    {
        Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
            "PreviewType" = "Plane"
            "CanUseSpriteAtlas" = "True"
        }
        // 源rgba*源a + 背景rgba*(1-源A值)   
        Blend SrcAlpha OneMinusSrcAlpha

        Cull Off ZWrite Off ZTest Always

        Pass
        {

            Stencil
            {
                Ref[_Stencil]
                Comp[_StencilComp]
                Pass[_StencilOp]
                ReadMask[_StencilReadMask]
                WriteMask[_StencilWriteMask]
            }
            ColorMask[_ColorMask]

            CGPROGRAM
            #pragma vertex vert     
            #pragma fragment frag     
            #include "UnityCG.cginc"     

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color : COLOR;
                half2 texcoord  : TEXCOORD0;
            };

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _MyColor;

            v2f vert(appdata_t IN)
            {
                v2f OUT;
                OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
                        OUT.texcoord = IN.texcoord;
                #ifdef UNITY_HALF_TEXEL_OFFSET     
                        OUT.vertex.xy -= (_ScreenParams.zw - 1.0);
                #endif     
                OUT.color = IN.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
                float grey = dot(color.rgb, fixed3(0.22, 0.707, 0.071));
                return half4(grey*_MyColor.r,grey*_MyColor.g,grey*_MyColor.b,color.a);
            }
            ENDCG
        }
    }
}