Spoiler: Info about V2 (uses dynamic lights instead)Once again, a third try, and this time it's even faster. Now, it uses sector colors instead of dynamic lighting, works in Zandronum's software renderer and runs way faster.
The "shadow map" is much more precise compared to the dynamic lights one, but is jaggier.
It still works in Zandronum and ZDoom, and also modern GZDoom.
You can use this in whichever way you need, while there's no need to credit me it would be nice if you did, also tell me when you end up using it because i would love to see the result!
Setting it up is easy, if a bit tedious. I recommend using GZDoom Builder for this. Make a grid of sectors which will be your "shadow map", i'd recommend making it 8x8, 16x16 or 32x32, depending on the size of the area the effect will be used in. The larger the area, the larger you want each sector to be. Tag them any random numbers (Just have them be all different and not conflicting with other tags) and place LightReciever in it, tag the light recievers other random numbers that don't conflict with the sectors. You might need to make a new actor that's a HateTarget, and then use Thing_Hate to make the light recievers target the HateTargets. After this you should be able to place monsters on the area. Sorry for not doing this myself but i just couldn't understand how these Thing_Hate things worked.
DOWNLOAD! V3 (Sector based)
DOWNLOAD! V2 (Dynamic light based)
DOWNLOAD!