Just FYI this is a very specific optimization for mc. Normally you have static terrain and precisely pre-calculate what geometry is hidden from different region

Just FYI this is a very specific optimization for mc. Normally you have static terrain and precisely pre-calculate what geometry is hidden from different regions and field of view and bake that information into the world. It's quite slow to do properly though. Mc generates dynamic terrains, so this is a dumber, faster version of that which is less accurate in identifying hidden geometry but fast enough to calculate when the world is generated and recalculate when terrain and field of view changes. The trick is finding the best heuristic for the geometry to maximize hidden surface detection without any false positives(since any missing geometry is probably going to be pretty noticeable).