Custom data Surface Shader example in the Built-In Render Pipeline

Important: The Built-In Render Pipeline is deprecated and will be made obsolete in a future release.

It remains supported, including bug fixes and maintenance, through the full Unity 6.7 LTS lifecycle.

The Universal Render Pipeline (URP) doesn’t support surface shaders. For more information on how to replace surface shaders in URP, refer to Convert custom shaders for URP compatibility.

Using a vertex modifier function, it is also possible to compute custom data in a vertex Shader, which then will be passed to the Surface Shader function per-pixel. The same compilation directive vertex:functionName is used, but the function should take two parameters: inout appdata_full and out Input. You can fill in any Input member that is not a built-in value there.

Note: Custom Input members used in this way must not have names beginning with ‘uv’ or they won’t work properly.

The example below defines a custom float3 customColor member, which is computed in a vertex function:

  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"
  }

In this example customColor is set to the absolute value of the normal:

Shader example that calculates values in the vertex shader and uses them in the fragment shader.

More practical uses could be computing any per-vertex data that is not provided by built-in Input variables; or optimizing Shader computations. For example, it’s possible to compute Rim lighting at the GameObject’s vertices, instead of doing that in the Surface Shader per-pixel.

Vertex modifier Surface Shader example in the Built-In Render Pipeline

Final color modifier Surface Shader example in the Built-In Render Pipeline

Unity Manual

Custom data Surface Shader example in the Built-In Render Pipeline