NGUI 可裁剪的灰度Shader

 Shader "Custom/Unlit - Transparent Colored Grayed (SoftClip)"
 {
     Properties
     {
         _MainTex ("Base (RGB)", 2D) = "white" {}
     }

     SubShader {
         LOD 

         Tags
         {
             "Queue" = "Transparent"
             "IgnoreProjector" = "True"
             "RenderType" = "Transparent"
         }

         pass
         {
             Cull Off
             Lighting Off
             ZWrite Off

             Offset -, -
             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;
             float4 _MainTex_ST;
             float2 _ClipSharpness = float2(20.0, 20.0);

             struct v2f
             {
                 float4 vertex : POSITION;
                 float4  pos : SV_POSITION;
                 float2  uv : TEXCOORD0;
                 float2 worldPos : TEXCOORD1;
             };

             v2f vert (appdata_base v)
             {
                 v2f o;
                 o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                 o.uv = v.texcoord;
                 o.worldPos = TRANSFORM_TEX(v.vertex.xy, _MainTex);
                 return o;
             };

             half4 frag (v2f i) : COLOR
             {
                 float2 factor = (float2(1.0, 1.0) - abs(i.worldPos)) * _ClipSharpness;
                 half4 texcol = tex2D (_MainTex, i.uv);
                 texcol.rgb = (texcol.r + texcol.g + texcol.b) / ;
                 texcol.a *= clamp( min(factor.x, factor.y), 0.0, 1.0);
                 return texcol;
             };
             ENDCG
         }
     }
     FallBack "Diffuse"
 }