I have never tried UV on a point light! I am learning new stuff.

I know on a spot light it's a circumscribed square, where the corners do not get involved. If we consider a circle in the UV space, I know that radius = 0 corresponds with the exact point line at the center of the light cone, and radius = .5 corresponds with the edge of the light cone. I can't remember which direction is "up" - it depends on the orientation of the light if I recall correctly.

The exact ratio of cone angle versus UV radius is unclear to me. It's not linear. What I mean by that is that if you consider a UV circle at radius = .25, this is not half the cone angle. I was trying to figure this out in detail a few months ago because I was building a Python script that could generate a Poser spotlight that produced the correct distribution specified in an IES light. Through various experiments I got really close, but not exact. One of the problems I had is that if you try to make a spotlight with a 180 degree cone, it fails.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)