. It's finally FUCKING WORKING!
 => Can now put as many probes in the scene as I want!
 => Each vertex processes at most 5 probes: the entry point probe, and its 4 neighbors
 => Faces that are still seeing no probe make complete sense in the scene: these are the ones that face away from probes and have a different material so their primitives are disconnected from others (no possible exchange of probe info)
. Need to test on the classic Sponza Atrium for comparison now...