Lit Shader - Light Variables

Suggestions & Feedback
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Hi dear devs,

Currently I’m trying to implement subsurface scattering effect into PlayCanvas just by changing refractionDynamicPS shader chunk. In process, I’ve encountered some difficulties about lights. Currently, lit-shader.js appends each lights code into fragment shader and each lights’ parameters are hard coded like light0_direction (also see below)
backend.append(" dAtten *= getSpotEffect(light" + i + "_direction,

I’m having a hard time reaching every lights variables while developing shader. I tried to set them in an array in lightDirPointPS currently. But light0_color is unreachable. (which means another patch in getFalloffLinear())

#define LIGHTS_AVAILABLE
int pointLightCount = 0;
vec3 lightPointsPos[255];

void getLightDirPoint(vec3 lightPosW) {
    dLightDirW = vPositionW - lightPosW;
    dLightDirNormW = normalize(dLightDirW);
    dLightPosW = lightPosW;
    lightPointsPos[pointLightCount] = dLightPosW;
    pointLightCount = pointLightCount + 1;
}

I think it would be nice to have lights values as arrays.

Btw, I wanna make PR about it but I’m stuck in this process. You can see effects results here: https://twitter.com/defektu_/status/1646825602530385920

Currently it has same light radius and intensity for each light. It would be cool to implement PlayCanvas’ default lights automatically.

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We have lights in an “array” when using clustered lighting (lights are stored in the texture). But accessing those is not very easy. I’m not sure how have a better suggestion apart from what you’re doing already.

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Thanks for the answer @mvaligursky

If I need to use Cluster Lighting, new definition like subsurfaceScatteringPS must be defined after clusteredLightPS to use decodeClusterLightCore(clusterLightData, lightIndex); to retrieve light properties from clusterLightData struct. Because refractionDynamicPS chunk is appended before clusteredLightPS struct and is out of scope. But I got the point about that matter.

Or I might add each SSS in each light (like in evaluateLight() & getLightDiffuse() and add it to dDiffuseLight). But I don’t know if it is performance wise. Any suggestions might help.

Reachable light struct in standart lighting might be helpful for developing shaders I guess.
Also customPS appended after everything like for doing material postFX may be good for easier access to shader chunks. (extensionPS & extensionVS is present in engine but never used.)