VXGI emissive lights and scattering

thanks to the help of the some great people i have managed to run vxgi light system.

i´d like to ask what are the current limitations. specifically:

  • can i get the fog to actually scatter light ? exponentialheightfog scattering settings do not change a thing in a vxgi setup.
    i understand this may be very expensive and complex so if its impossible, any chance of a viable workaround?

  • do emissive materials bounce light aswell? if not, is there some other way of setting up area lights or getting very soft shadows.

actually stunned of UE capabilities, just trying to figure out the general limits so any info is appreciated.
i already read a bunch of threads on vxgi but its difficult to ascertain what state of matter is.

VXGI does not affect fog, I think that’s only affected by direct lighting.
Emissive materials can emit light, try it out it’s pretty cool.

thank you very much for a fast reply.

  • does that mean that there is no chance of faking light scattering within fog? basically i am thinking i would just need to pipe something like capture of the environment into the fog colour slot, and perhaps use the zdepth to finetune it. very new to unreal so i am just swinging here.

  • i have tried emissive light but what i really meant was whether this emissive light can produce bounces or light bleeding. tried it real quick but no dice.


-You can fake light scattering in fog by using sheets/beams with a lit material on them.
It’s crude but it works.

-Emissive with VXGI does bounce light. Just don’t expect raytraced miracles from it.
Make sure your material is flagged as omni-directional under the VXGI properties of it.

You could try putting a stationary light where you want the scattering to take place, not sure if that gets counted. Otherwise you’ll have to know some more technical information to be able to create a solution.
I believe that for emissive textures it already counts a bounce so it needs two bounces to work.

i will be looking out for some workaround. ty.