If your sprites are semi transparent it probably isn't worth it.
They are not semi transparent.
Introducing FBO binds means less batching and more state switches
When zoomed out, it's better to have a few prerendered chunks, than half milion of tiles. (yet they need their depth values preserved)
I even packed tile mesh to VBO. New machines don't have a problem with million tris, but it really is a bottleneck on older ones.
I appreciate your advices, but I already know that stuff
(sprite batching and texture atlases)
but you can't always fit all your sprites into one atlas. Terrain has it's separate atlas and I don't want to switch between objects and terrain atlases, depth buffer solved that so far. (and terrain is not flat, some objects can be behind some parts of terrain)
It's more of a testing ground, and I have a few ideas on my mind.
I'm going off to sleep now and I hoped that meanwhile someone would share what they know about FBO usage.
How to render FBO's content preserving it's depth values is all I'm asking for.