First of all, my game is 2D with textured quads using OpenGL. I want to implement lighting, but i won't be using "actual" lighting. To do that, i can sort of fake it by layering an alpha-blended textured quad of a "light sphere" and do additive blending. But now i want the reverse: imagine a light in a dark cave. If the cave is black and i slap my textured quad down, i just get grey. That does not work. Let's say this is my unlit game screen for example (just a mockup): I want to be able to have my "lamp" light up the dark like so: I can do that by having a black texture with a whole cut out of it to simulate a restricted field of vision but the real problem is what happens when i have several light sources for an effect like this: My question is: Do you know of any OpenGL extratrickery that will do this? Some kind of blending technique? Thanks for your help. I really do appreciate it.

Well, i think that is on the right track, but if i understand what a lightmap is, it's something you apply to each and every quad you lay down, correct? What i'm looking for is more of an overlay for the whole scene. Here is a reduced version of my current collision physics testing facility:



If i "turned out the lights" so to speak, and lit a lamp, i want it to look like this (mockup):



I hope that was a little more clear

Diablo 2 had it, if I'm not mistaken.

I don't know that simple blending will do the trick for you. Your best bet might be to generate the lightmap per-frame in a texture and use that with multiplicative blending.