Version: 2021.3
Surface Shader examples
Surface Shader lighting examples

Custom lighting models in Surface Shaders

In the Built-in Render PipelineA 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
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, when writing Surface ShadersA streamlined way of writing shaders for the Built-in Render Pipeline. More info
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, you describe the properties of a surface (such as albedo color and normal), and a Lighting Model computes the lighting interaction.

Render pipeline compatibility

Feature name Built-in Render Pipeline Universal Render Pipeline (URP) High Definition Render Pipeline (HDRP) Custom SRP
Surface Shaders Yes No

For a streamlined way of creating Shader objects in URP, see Shader Graph.
No

For a streamlined way of creating Shader objects in HDRP, see Shader Graph.
No

Overview

There are two built-in lighting models: Lambert for diffuse lighting, and BlinnPhong for specular lighting. The Lighting.cginc file inside Unity defines these models (Windows: <unity install path>/Data/CGIncludes/Lighting.cginc; macOS: /Applications/Unity/Unity.app/Contents/CGIncludes/Lighting.cginc).

Sometimes you might want to use a custom lighting model. You can do this with Surface ShadersA program that runs on the GPU. More info
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. A lighting model is simply a couple of Cg/HLSL functions that match some conventions.

Declaring lighting models

A lighting model consists of regular functions with names that begin Lighting. You can declare them anywhere in your shader file, or one of the included files. The functions are:

  1. half4 Lighting<Name> (SurfaceOutput s, UnityGI gi); Use this in forward rendering pathsThe technique that a render pipeline uses to render graphics. Choosing a different rendering path affects how lighting and shading are calculated. Some rendering paths are more suited to different platforms and hardware than others. More info
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    for light models that are not dependent on the view direction.

  2. half4 Lighting<Name> (SurfaceOutput s, half3 viewDir, UnityGI gi); Use this in forward renderingA rendering path that renders each object in one or more passes, depending on lights that affect the object. Lights themselves are also treated differently by Forward Rendering, depending on their settings and intensity. More info
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    paths for light models that are dependent on the view direction.

  3. half4 Lighting<Name>_Deferred (SurfaceOutput s, UnityGI gi, out half4 outDiffuseOcclusion, out half4 outSpecSmoothness, out half4 outNormal); Use this in deferred lighting paths.

  4. half4 Lighting<Name>_PrePass (SurfaceOutput s, half4 light); Use this in light prepass (legacy deferred) lighting paths.

Note that you don’t need to declare all functions. A lighting model either uses view direction or it does not. Similarly, if the lighting model only works in forward rendering, do not declare the _Deferred or _Prepass function. This ensures that Shaders that use it only compile to forward rendering.

Custom GI

Declare the following function to customize the decoding lightmapA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
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data and probes:

  1. half4 Lighting<Name>_GI (SurfaceOutput s, UnityGIInput data, inout UnityGI gi);

Note that to decode standard Unity lightmaps and SH probes, you can use the built-in DecodeLightmap and ShadeSHPerPixel functions, as seen in UnityGI_Base in the UnityGlobalIllumination.cginc file inside Unity (Windows: <unity install path>/Data/CGIncludes/UnityGlobalIllumination.cginc; macOS: /Applications/Unity/Unity.app/Contents/CGIncludes/UnityGlobalIllumination.cginc_).

Examples

See documentation on Surface Shader Lighting Examples for more information.

Surface Shader examples
Surface Shader lighting examples