[req][perf] OpenGL bounding box for instances /camera update

[CTZn]

Proposing to resolve instances based on one mesh to one bbox, ie if grassland uses 6 different meshes then 6 cubes would be used for its bounding boxes. That's the obvious way to do it I think...

The issue has been pointed to often recently so I thought it deserved a thread ! Heck, it did annoy me too.

[CTZn]

On a second note, I am wondering about the so-called GPU "infinite details" instancing scheme... any chance ? I guess I'm pushing my luck, again