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Unity Engine

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Unity Engine

Set the lighting model in a Surface Shader in the Built-In Render Pipeline

Set the lighting to a built-in model, or define a custom lighting model.
阅读时间3 分钟最后更新于 1 个月前
In the Built-in Render Pipeline, when writing Surface Shaders, you describe the properties of a surface (such as albedo color and normal), and a Lighting Model computes the lighting interaction.
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/Resources/CGIncludes/Lighting.cginc; macOS: /Applications/Unity/Unity.app/Contents/Resources/CGIncludes/Lighting.cginc).
Sometimes you might want to use a custom lighting model. You can do this with Surface Shaders. A lighting model is simply a couple of Cg/HLSL functions that match some conventions.

Render pipeline compatibility

Feature name

Universal Render Pipeline (URP)

High Definition Render Pipeline (HDRP)

Custom SRP

Built-in Render Pipeline

Surface ShadersNo

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.		NoYes

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 paths 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 rendering 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 shading 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
function. This ensures that Shaders that use it only compile to forward rendering.

Custom GI

Declare the following function to customize the decoding lightmap data and probes:
  1. void 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/Resources/CGIncludes/UnityGlobalIllumination.cginc; macOS: /Applications/Unity/Unity.app/Contents/Resources/CGIncludes/UnityGlobalIllumination.cginc_).

Example

The following is an example of a shader that uses the built-in Lambert lighting model:
  Shader "Example/Diffuse Texture" {    Properties {      _MainTex ("Texture", 2D) = "white" {}    }    SubShader {      Tags { "RenderType" = "Opaque" }      CGPROGRAM      #pragma surface surf Lambert            struct Input {          float2 uv_MainTex;      };            sampler2D _MainTex;            void surf (Input IN, inout SurfaceOutput o) {          o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;      }      ENDCG    }    Fallback "Diffuse"  }
Here's how it looks like with a Texture and without a Texture, with one directional Light in the Scene:

Shader using a diffuse texture.

Shader without a diffuse texture.