Unity3D使用Shader实现腐蚀消失

Shader "XM/CorrosionEffect" { Properties { _Color ("Color", Color) = (1,1,1,1) _MainTex ("Albedo (RGB)", 2D) = "white" {} _Glossiness ("Smoothness", Range(0,1)) = 0.5 _Metallic ("Metallic", Range(0,1)) = 0.0 _ClipMaskTex ("Clip Mask", 2D) = "white" {} _ClipGray ("Clip Alpha", Range(0.0,1.0)) = 0.0 _ClipLineSize ("Clip Line Size", Range(0,1)) = 0.0 _ClipLineColor("Clip Line Color", Color) = (1,1,1,1) } SubShader { Tags { "RenderType"="Opaque" } LOD 200 CGPROGRAM // Physically based Standard lighting model, and enable shadows on all light types #pragma surface surf Standard fullforwardshadows // Use shader model 3.0 target, to get nicer looking lighting #pragma target 3.0 sampler2D _MainTex; sampler2D _ClipMaskTex; struct Input {  float2 uv_MainTex; }; half _Glossiness; half _Metallic; fixed4 _Color; fixed _ClipGray; fixed _ClipLineSize; fixed4 _ClipLineColor; void surf (Input IN, inout SurfaceOutputStandard o) {  fixed4 m = tex2D (_ClipMaskTex, IN.uv_MainTex);  fixed gray = Luminance(m.rgb);  if(gray >= _ClipGray)  {  clip(-1);  }  fixed4 c;  if(gray >= _ClipGray - _ClipLineSize)  {  c = _ClipLineColor;  }  else  {  // Albedo comes from a texture tinted by color  c = tex2D (_MainTex, IN.uv_MainTex) * _Color;  }  o.Albedo = c.rgb;  // Metallic and smoothness come from slider variables  o.Metallic = _Metallic;  o.Smoothness = _Glossiness;  o.Alpha = c.a; } ENDCG } FallBack "Diffuse"}