Pretty much like everybody, I've been using FBOs for a long time. Then today I got thinking and realized I did not understand everything in FBOs, and particularly the "interest" of some of the features of the API. Maybe it was done to be future proof and has no immediate interest, I don't know, but here are some questions that are kind of puzzling me:
1) What is the interest of creating more than 1 FBO ? Even if you want to render to many textures per frame, you can just use the same FBO and bind/unbind the color/depth textures/buffers. It's also much faster since on Vista, a FBO switch is, as I discovered, extremely slow.
2) What is the interest of using render buffers in place of textures ? Think of using a depth texture instead of a depth buffer everywhere: you get the ability to use this depth texture in other passes for free. Is rendering to a texture slower than rendering to a buffer ? (Note: the only exception I can understand is for using multi-sampling, then you *have to* use an intermediary buffer).