In Doom3 shaders there are “light projection texture” and “light falloff texture”. What exactly these textures are? May be I know, but with different terminology.



“light projection texture” : for example it is the round spot of your maglite you see when facing a wall. Or the faked grates’ soft shadows.
Let’s say it is the XY plane.

“light falloff texture” : Two guesses :
a) the same principle, but separated so that you can do combinations of falloff/projection (ex narrow falloff and grate projection).
b) or it is the distance falloff from light source to objects, ie. a Z-theta plane. So instead of using math to calculate attenuation, it is precalculated.