Vertex Modifier of Surface Shader

【Vertex Modifier of Surface Shader】

　　Surface shader compilation directive vertex:functionName  可以用于指定顶点着色器。A function that takes inout appdata_full parameter.

　　Surface shader中顶点函数传出的坐标必须是Local坐标。在Vert执行完毕后，Surface shader会自动将此Local坐标乘以MVP矩阵。

 Shader "Example/Normal Extrusion" {
     Properties {
       _MainTex ("Texture", 2D) = "white" {}
       _Amount ("Extrusion Amount", Range(-,)) = 0.5
     }
     SubShader {
       Tags { "RenderType" = "Opaque" }
       CGPROGRAM
       #pragma surface surf Lambert vertex:vert
       struct Input {
           float2 uv_MainTex;
       };
       float _Amount;
       void vert (inout appdata_full v) {
           v.vertex.xyz += v.normal * _Amount;
       }
       sampler2D _MainTex;
       void surf (Input IN, inout SurfaceOutput o) {
           o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
       }
       ENDCG
     }
     Fallback "Diffuse"
   }

　　

　　如果想传递给surface自定义数据（per-pixel），顶点函数需要添加out Input 参数如下：

   Shader "Example/Custom Vertex Data" {
     Properties {
       _MainTex ("Texture", 2D) = "white" {}
     }
     SubShader {
       Tags { "RenderType" = "Opaque" }
       CGPROGRAM
       #pragma surface surf Lambert vertex:vert
       struct Input {
           float2 uv_MainTex;
           float3 customColor;
       };
       void vert (inout appdata_full v, out Input o) {
           UNITY_INITIALIZE_OUTPUT(Input,o);
           o.customColor = abs(v.normal);
       }
       sampler2D _MainTex;
       void surf (Input IN, inout SurfaceOutput o) {
           o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
           o.Albedo *= IN.customColor;
       }
       ENDCG
     }
     Fallback "Diffuse"
   }

　　

参考：file:///C:/Program%20Files%20(x86)/Unity/Editor/Data/Documentation/html/en/Manual/SL-SurfaceShaderExamples.html