How to implement custom lighting for the Forward+ rendering path with ShaderGraph. The project is using Unity 2022年3月10日f1.
This repository expands on NedMakesGame's awesome "Creating Custom Lighting in Unity's Shader Graph with Universal Render Pipeline " tutorial. I've just made some tweaks to work with Additional Lights in Forward+.
- NedMakesGame's tutorial uses as a base the Unlit Universal RP shader graph, so to make the lighting work with Forward+, there needs to be one more multi_compile keyword added: _FORWARD_PLUS.
Screenshot of the keyword in _FORWARD_PLUS SG_TestLighting.shadergraph
- Forward+ needs light loop macros LIGHT_LOOP_BEGIN and LIGHT_LOOP_END to iterate through the lights, and this loop requires a local variable of type InputData.
#ifdef _FORWARD_PLUS
uint lightsCount = GetAdditionalLightsCount();
InputData inputData = (InputData)0;
inputData.positionWS = d.positionWS;
inputData.normalWS = d.normalWS;
inputData.viewDirectionWS = d.viewDirectionWS;
inputData.shadowCoord = d.shadowCoord;
float4 screenPos = float4(d.positionCS.x, (_ScaledScreenParams.y - d.positionCS.y), 0, 0);
inputData.normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(screenPos);
LIGHT_LOOP_BEGIN(lightsCount)
Light light = GetAdditionalLight(lightIndex, d.positionWS);
lightColor += CustomLightHandling(d, light);
LIGHT_LOOP_END
#endif //end _FORWARD_PLUS
- Because of how culling works in Forward+, it won't find additional lights when the camera is at a certain distance, so you'll need to make sure to check the clip space position for it to work.
Screenshot of how to fetch the clip position with theScreenPosition node and the Mode set to Pixel
The following screenshot shows a comparison between the Universal RP Lit shader and the custom ShaderGraph shader, and both show the result with 3 Point Lights.
Comparison GIF between additional lights in Lit and the custom ShaderGraph shader
