Reading current framebuffer

Question

Is there a way to read fragment from the framebuffer currently rendered?

So, I\'m looking for a way to read color information from the fragment that\'s on the place that

Answer 1

With most nVidia hardware you can use the GL_NV_texture_barrier extension to read from a texture that's currently bound to a framebuffer. But bear in mind that you won't be able to read data any more recent than produced in the previous draw call