Making a effecient Fog of war system

What is the best way to go about this? I saw a guys tutorial but it was inneficient, Maybe trigger lights and some coding? Any ideas?

I found this but hate unity hmmm good thing ue4 is source idk people point me in a direction please it will be dynamic for a combat game melee/ swords etc some crosbows and bows
Maybe a module that saves some light data but not certain things thats there like player etc unless its loaded

I saw a C++ version of how to do it in the community content sub-forum, it shouldn’t take too long to find.

Thats the one i’m talking about and he uses a non efficient method.