I've started learning how to use OpenGL ES, and am trying to do some general purpose computing using the Pi's GPU. I've got it mostly working, but I'm hung up on the last step: getting a framebuffer object (FBO) back to the CPU memory so I can manipulate it.
I see that one method is to use the glReadPixels() function. Would this be a bottleneck if I'm transferring large framebuffers back to the CPU in real-time? Is there a proper way of doing it? I found a few instances of people mentioning using the KHR_image EGL extension, but haven't found any solid examples.