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Unity Engine

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Unity Engine

Use indirect lighting in a custom URP shader

Use reflection probes or Adaptive Probe Volumes in a URP shader.
阅读时间3 分钟最后更新于 25 天前
To use indirect lighting in a custom Universal Render Pipeline (URP) shader, follow these steps:
  1. Add an 
    #include
    line inside the 
    HLSLPROGRAM
    block in your shader file. Refer to the sections on this page for specific include file paths.
  2. Use any of the methods from the following sections.

Use reflection probes in a custom URP shader

To use reflection probes or the skybox, use the following 
#include
line:
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/GlobalIllumination.hlsl"

Method

Syntax

Description

GlossyEnvironmentReflection
half3 GlossyEnvironmentReflection(half3 reflectVector, float3 positionWS, half perceptualRoughness, half occlusion, float2 normalizedScreenSpaceUV)
Samples reflection probes if the object is within a reflection probe volume. Samples the skybox otherwise. The function supports reflection probe blending.
The 
perceptualRoughness
argument selects the mip level of the sampled texture. The higher the value, the more blurred the reflections look.
The 
occlusion
argument is the reflection probe attenuation factor.
The 
normalizedScreenSpaceUV
argument is the normalized screen space position of the fragment.
The 
GlossyEnvironmentReflection
function has the following simpler overload, which does not support blending:
half3 GlossyEnvironmentReflection(half3 reflectVector, half perceptualRoughness, half occlusion)

Sample Adaptive Probe Volumes

To sample Adaptive Probe Volumes (APV), use the following 
#include
line:
#include "Packages/com.unity.render-pipelines.core/Runtime/Lighting/ProbeVolume/ProbeVolume.hlsl"

Method

Syntax

Description

EvaluateAdaptiveProbeVolume
void EvaluateAdaptiveProbeVolume(in float3 posWS, in float3 normalWS, in float3 viewDir, in float2 positionSS, in uint renderingLayer, out float3 bakeDiffuseLighting)
Samples lighting from Adaptive Probe Volumes.
The 
positionSS
argument is the screen space position of a fragment that is being rendered.
The 
renderingLayer
argument is the rendering layer mask.

Sample light probes

To sample light probes, use the following 
#include
line:
#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/AmbientProbe.hlsl"

Method

Syntax

Description

SampleSH
real3 SampleSH(real3 normalWS)
Sample light probes.

Example

The following URP shader code computes diffuse and specular ambient light using the 
GlossyEnvironmentReflection
function.
float3 CustomLightingAmbient(float3 BaseColor, 							float3 NormalWS, 							float Metallic, 							float Smoothness, 							float Reflectance, 							float AmbientOcclusion, 							float PositionWS, 							float2 screenspaceUV, 							float3 ViewDirWS){    // Diffuse ambient lighting.	// Sample the sky probe with high roughness and use a normal vector instead of	// a reflection vector to approximate ambient light	float3 DiffuseAmbient = GlossyEnvironmentReflection(NormalWS, PositionWS, 1, 1, screenspaceUV);	// If the surface is metallic, set ambient to zero, otherwise multiply by BaseColor	DiffuseAmbient *= lerp(BaseColor, float3(0,0,0), Metallic);    // Specular ambient lighting - reflections	// Surfaces are more reflective at glancing angles. Compute the fresnel value for reflectance.	float Fresnel = pow((1 - dot(NormalWS, ViewDirWS)), 5);	// Reflectance is 100% at the glancing angle	Reflectance = lerp(Reflectance, 1, Fresnel);	// If the object is metal, use the base color for reflectance instead.	float3 ReflectionColor = lerp(float3(Reflectance, Reflectance, Reflectance), BaseColor, Metallic);	// Compute the reflection vector and use it to sample the sky probe for reflections.	float3 ReflectionVector = reflect(-ViewDirWS, NormalWS);	float3 SpecularAmbient = GlossyEnvironmentReflection(ReflectionVector, PositionWS, 1 - Smoothness, 1, screenspaceUV);		return (DiffuseAmbient + SpecularAmbient) * AmbientOcclusion;}

Shader graph custom function node example

Shader Graph Feature Examples contain examples of custom lighting models.
To learn how to use the 
GlossyEnvironmentReflection
function in a custom function node:
  1. In the example scene, open the CustomLightingSimple shader graph.
  2. Navigate to the SampleReflectionProbes sub-graph.
  3. Inspect the URPReflectionProbe node. The node contains the HLSL code that uses the 
    GlossyEnvironmentReflection
    function:
    #ifdef SHADERGRAPH_PREVIEW    reflection = float3(0,0,0);#else    reflection = GlossyEnvironmentReflection(reflectVector, positionWS, roughness, 1.0h, screenspaceUV);#endif

Additional resources