I don''t know if any of you noticed but .... If you create and run an empty OpenGL application that doesn''t clear the buffer and doesn''t draw anything, but just swaps buffers. And If you run another OpenGL Application that does something before that.... Then this empty OpenGL app will display the last buffer of the previous openGL application.

Oh yes this is known. =) The same thing happens in DirectDraw (Dx7) and in DirectX Graphics(Dx8 & Dx9)when you swap the primary with the secondary buffer without clearing it.

Another more interesting effect is that when you play a game, like Aliens Vs. Predator 2 and then initialize a backbuffer swapping application, then you''ll see images of the game itself being displayed instead of random junk of memory. =)

Hmm can you do a glReadPixels or what ever the function is to get the color of a pixel on this swaping program?