Unity shader实现遮罩效果

Shader "Custom/Mask" { Properties { _MainTex ("Base (RGB)", 2D) = "white" {}//目标图片，即需要被遮罩的图片 _MaskLayer("Culling Mask",2D) = "white"{}//混合的图片，设置为白色的图片，任何颜色与白色混合，其颜色不变 _Cutoff("Alpha cutoff",Range(0,1)) = 0 } SubShader { Tags {   "Queue"="Transparent"  }//渲染队列设置为 以从后往前的顺序渲染透明物体 Lighting off //关闭光照 ZWrite off //关闭深度缓存 Blend off //关闭混合 AlphaTest GEqual[_Cutoff] //启用alpha测试 Pass{  SetTexture[_MaskLayer]{combine texture}//混合贴图  //混合贴图，previous为放置在前一序列这样在进行AlphaTest的时候会以这个图片为主来进行混合  SetTexture[_MainTex]{combine texture,previous} }  }}

Shader "Custom/CircleMask" {  Properties {    _MainTex ("MainTex", 2D) = "white" {}    _MaskTex ("MaskTex", 2D) = "white" {}    [HideInInspector]_Cutoff ("Alpha cutoff", Range(0,1)) = 0.5    //MASK SUPPORT ADD    _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    //MASK SUPPORT END  }  SubShader {    Tags {      "IgnoreProjector"="True"      "Queue"="Transparent"      "RenderType"="Transparent"    }    //MASK SUPPORT ADD    Stencil    {      Ref [_Stencil]      Comp [_StencilComp]      Pass [_StencilOp]      ReadMask [_StencilReadMask]      WriteMask [_StencilWriteMask]    }    ColorMask [_ColorMask]    //MASK SUPPORT END    Pass {      Name "FORWARD"      Tags {        "LightMode"="ForwardBase"      }      Blend SrcAlpha OneMinusSrcAlpha      ZWrite Off      CGPROGRAM      #pragma vertex vert      #pragma fragment frag      #define UNITY_PASS_FORWARDBASE      #include "UnityCG.cginc"      #pragma multi_compile_fwdbase      #pragma only_renderers d3d9 d3d11 glcore gles      #pragma target 3.0      uniform sampler2D _MainTex; uniform float4 _MainTex_ST;      uniform sampler2D _MaskTex; uniform float4 _MaskTex_ST;      struct VertexInput {        float4 vertex : POSITION;        float2 texcoord0 : TEXCOORD0;      };      struct VertexOutput {        float4 pos : SV_POSITION;        float2 uv0 : TEXCOORD0;      };      VertexOutput vert (VertexInput v) {        VertexOutput o = (VertexOutput)0;        o.uv0 = v.texcoord0;        o.pos = UnityObjectToClipPos( v.vertex );        return o;      }      float4 frag(VertexOutput i) : COLOR {////// Lighting:        float4 _MainTex_var = tex2D(_MainTex,TRANSFORM_TEX(i.uv0, _MainTex));        float3 finalColor = _MainTex_var.rgb;        float4 _MaskTex_var = tex2D(_MaskTex,TRANSFORM_TEX(i.uv0, _MaskTex));        return fixed4(finalColor,_MaskTex_var.a);      }      ENDCG    }  }  FallBack "Diffuse"}