Thats a main stuff which im working on. Im not a math guy (im, probaby more like a meth guy just joking), and unfortunately not a code guy, so the whole system are pretty rought approximation of 1st light bounce and, ofcourse, not physically correct, but im personally profess the point of view where “look nice or artistic > prysically correct”.
In some ideal cases the system gives really nice and pretty realistic results and illusion of light bounce.
Currently performance was measured in editor with a lot of stuff runned in the background like Photoshop and Google Chrome with a lot of bookmarks opened, and cost for 1 dynamic light are really not so big. But anyway, at the moment im not implement some features, so final performance cost will be different (and probably higher). But more or less, all implemented features will be have constant cost, cause whole system are scene complexity independent, which are good
Dynamic lighting with GI and any kind of simulation of GI comes to my mind after Alien: Isolation. The most perfect light in the video games in my opinion.
Basically i was start to learn UE4 after deside to make my own game in similar 80s retro-futuristic sci-fi style highly inspired by Alien:Isolation.
By many reasons i quickly realize what Lighmass system are look nice, yeah, but really not pleasure to work with beacause of a lot of unwrapping work, bakes, errors and artifacts, rebakes and so on many-many iterations!. Also lightmass are static as we know, and im clearly remember how nice and funny was light in Dead Space, as example, where you can shoot on them and turn them off! Bloody nice!
So, after trying of LPV (which are currently dead in UE4) and VXGI (also dead), i realize what i need something different, and by many reason RTX are not the answer.
After many trials and errors i think im, at least found the right direction to work and evolve, the system which i call - QIBL.
But that this abbreviation means?! Well, lets leave this to another post and updates
Uncompressed image: https://ibb.co/1sLTJzR
Sorry about the video quality. Looks like NVidia capture cant provide good results.