Unity Shader 灰度Shader(支持UGUI Mask裁剪)

Unity Shader 灰度Shader(支持UGUI Mask裁剪)

shader源码如下 其中支持mask裁剪部分（注意 有两处地方需要添加）的代码同样适合其他自定义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
		}
	}
}

！！注意：

支持Mask后在Mask物体下，Image的Material的属性只有第一次赋值时有效，无法动态修改，如果有需求就要新建一个脚本继承Image并重写GetModifiedMaterial方法。

重写代码如下

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