use-built-in-shader-methods-lighting.md 5.4KB
uid: urp-docfx-use-built-in-shader-methods-lighting
Use lighting in a custom URP shader
To use lighting in a custom Universal Render Pipeline (URP) shader, follow these steps:
- Add
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"inside theHLSLPROGRAMin your shader file. - Use any of the methods from the following sections.
Get light data
The Lighting.hlsl file imports the RealtimeLights.hlsl file, which contains the following methods.
| Method | Syntax | Description |
|-|-|-|
| GetMainLight | Light GetMainLight() | Returns the main light in the scene. |
| GetAdditionalLight | Light GetAdditionalLight(uint lightIndex, float3 positionInWorldSpace) | Returns the lightIndex additional light that affects positionWS. For example, if lightIndex is 0, this method returns the first additional light. |
| GetAdditionalLightsCount | int GetAdditionalLightsCount() | Returns the number of additional lights. |
Refer to Use shadows in a custom URP shader for information on versions of these methods you can use to calculate shadows.
Calculate lighting for a surface normal
| Method | Syntax | Description |
|-|-|-|
| LightingLambert | half3 LightingLambert(half3 lightColor, half3 lightDirection, half3 surfaceNormal) | Returns the diffuse lighting for the surface normal, calculated using the Lambert model. |
| LightingSpecular | half3 LightingSpecular(half3 lightColor, half3 lightDirection, half3 surfaceNormal, half3 viewDirection, half4 specularAmount, half smoothnessAmount) | Returns the specular lighting for the surface normal, using simple shading. |
Calculate ambient occlusion
The Lighting.hlsl file imports the AmbientOcclusion.hlsl file, which contains the following methods.
| Method | Syntax | Description |
|-|-|-|
| SampleAmbientOcclusion | half SampleAmbientOcclusion(float2 normalizedScreenSpaceUV) | Returns the ambient occlusion value at the position in screen space, where 0 means occluded and 1 means unoccluded. |
| GetScreenSpaceAmbientOcclusion | AmbientOcclusionFactor GetScreenSpaceAmbientOcclusion(float2 normalizedScreenSpaceUV) | Returns the indirect and direct ambient occlusion values at the position in screen space, where 0 means occluded and 1 means unoccluded. |
Refer to Ambient occlusion for more information.
Structs
AmbientOcclusionFactor
Use the GetScreenSpaceAmbientOcclusion method to return this struct.
| Field | Description |
|-|-|
| half indirectAmbientOcclusion | The amount the object is in shadow from ambient occlusion caused by objects blocking indirect light. |
| half directAmbientOcclusion | The amount the object is in shadow from ambient occlusion caused by objects blocking direct light. |
Light
Use the GetMainLight and GetAdditionalLight methods to return this struct.
| Field | Description |
|-|-|
| half3 direction | The direction of the light. |
| half3 color | The color of the light. |
| float distanceAttenuation | The strength of the light, based on its distance from the object. |
| half shadowAttenuation | The strength of the light, based on whether the object is in shadow. |
| uint layerMask | The layer mask of the light. |
Example
The following URP shader draws object surfaces with the amount of light they receive from the main directional light.
Shader "Custom/LambertLighting"
{
SubShader
{
Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" }
Pass
{
HLSLPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
struct Attributes
{
float4 positionOS : POSITION;
float2 uv: TEXCOORD0;
};
struct Varyings
{
float4 positionCS : SV_POSITION;
float2 uv: TEXCOORD0;
half3 lightAmount : TEXCOORD2;
};
Varyings vert(Attributes IN)
{
Varyings OUT;
OUT.positionCS = TransformObjectToHClip(IN.positionOS.xyz);
// Get the VertexNormalInputs of the vertex, which contains the normal in world space
VertexNormalInputs positions = GetVertexNormalInputs(IN.positionOS);
// Get the properties of the main light
Light light = GetMainLight();
// Calculate the amount of light the vertex receives
OUT.lightAmount = LightingLambert(light.color, light.direction, positions.normalWS.xyz);
return OUT;
}
half4 frag(Varyings IN) : SV_Target
{
// Set the fragment color to the interpolated amount of light
return float4(IN.lightAmount, 1);
}
ENDHLSL
}
}
}