chris wells

thank you for the info,

how in a karma shader can I identify if a surface is receiving light from a source. Imagine things start to glow when ever a shadow covers them. I thought I could just brute force it and build something in sops, but I can't import LOP lights into a sop context.

There are AOV's that give you that type of info, but I actually want it in the shader, and not some comp post process.
Any ideas?

Thanks

Thank you Soothsayer, That's another great option. For anyone looking into this in the future, the vex is, assuming your volume is plugged into the second input: