I'm doing heavy computation using the GPU, which involves a lot of render-to-texture operations. It's an iterative computation, so there's a lot of rendering to a texture, then rendering that texture to another texture, then rendering the second texture back to the first texture and so on, passing the texture through a shader each time.
My question is: is it better to have a separate FBO for each texture I want to render into, or should I rather have one FBO and bind the target texture using glFramebufferTexture2D each time I want to change render target?
My platform is OpenGL ES 2.0 on the iPhone.
On the iPhone implementation, it is inexpensive to change the attachment, assuming the old and new textures are the same dimensions/format/etc. Otherwise, the driver has to do some additional work to reconfigure the framebuffer.