Probe lighting stuff is starting to look good now. Still some odd looking things in a couple of places.
The soft shadow of the Box is kind of borked since I threw in some hacks to avoid self-shadowing. (It's an SDF technique)

This should work with dynamic objects and light sources, but I have not tested that yet.

Also I think I can get this to be a lot faster, since the implementation is very inefficient in many places. It's currently at ~12 ms. Something like 4 or 5 ms would be more desirable, considering how simple the scene is.