ShaderLab: defining a SubShader

To define a SubShader in ShaderLabUnity’s language for defining the structure of Shader objects. More info
See in Glossary, you use a SubShader block. This page contains information on using SubShader blocks.

For information on how a ShaderA program that runs on the GPU. More info
See in Glossary object works, and the relationship between Shader objectsAn instance of the Shader class, a Shader object is container for shader programs and GPU instructions, and information that tells Unity how to use them. Use them with materials to determine the appearance of your scene. More info
See in Glossary, SubShaders and Passes, see Shader objects introduction.

Overview

A Shader object contains one or more SubShaders. SubShaders let you define different GPU settings and shader programs for different hardware, render pipelinesA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary, and runtime settings. Some Shader objects contain only a single SubShader; others contain multiple SubShaders to support a range of different configurations.

Render pipeline compatibility

Feature name	Built-in Render Pipeline	Universal Render Pipeline (URP)	High Definition Render Pipeline (HDRP)	Custom SRP
ShaderLab: SubShader block	Yes	Yes	Yes	Yes

Using the SubShader block

In ShaderLab, you define a SubShader by placing a SubShader block inside a Shader block.

Inside the SubShader block, you can:

Assign a LODThe Level Of Detail (LOD) technique is an optimization that reduces the number of triangles that Unity has to render for a GameObject when its distance from the Camera increases. More info
See in Glossary (level of detail) value to the SubShader, using the LOD block. See assigning a LOD value to a SubShader.
Assign key-value pairs of data to the SubShader, using the Tags block. See ShaderLab: assigning tags to a SubShader.
Add GPU instructions or shader code to the SubShader, using ShaderLab commands. See ShaderLab: using commands.
Define one or more Passes, using the Pass block. See ShaderLab: defining a Pass.
Specify package requirements using the PackageRequirements block. This makes Unity only run the SubShader if the required packages are installed. See ShaderLab: specifying package requirements.

Signature	Function
`SubShader` `{` `<optional: LOD>` `<optional: tags>` `<optional: commands>` `<One or more Pass definitions>` `}`	Defines a SubShader. You can define as many Passes as you like within a SubShader.

Examples

This example code demonstrates the syntax for creating a Shader object that contains a single SubShader, which in turn contains a single Pass.

Shader "Examples/SinglePass"
{
    SubShader
    {
        Tags { "ExampleSubShaderTagKey" = "ExampleSubShaderTagValue" }
        LOD 100

         // ShaderLab commands that apply to the whole SubShader go here. 

        Pass
        {                
              Name "ExamplePassName"
              Tags { "ExamplePassTagKey" = "ExamplePassTagValue" }

              // ShaderLab commands that apply to this Pass go here.

              // HLSL code goes here.
        }
    }
}

ShaderLab: assigning a custom editor

ShaderLab: assigning tags to a SubShader