I have to say this HISM_FoW variant for each mesh is just giving wayyy too much headaches. And frankly doen’t even look as good as decals placed over each tile.
Honestly I simply hadn’t considered using decals before, but it seems much easier to manage, and a quick test on the 20x20 map didn’t seem to give any performance problems if I filled it up completely with decals.
So yeah, bye bye HISM_FoW. Hello decals!