   Question on Thread Rendering
  I have a question about rendering in a thread.  Currently, I render a complex image to the back buffer with the glDrawElements and vertex arrays.  I needed to implement a method of drawing a new smaller element to my scene without having to redraw the entire scene.  Every time I render my complex main scene I copy it to a textured rectangle which is the same size as my view port.  When I need to add a quick small object to my scene without having to redraw the entire complex main scene, I render the textured rectangle to the screen then I draw my small object.  (Note: My renders are in 2D).  In this fashion, I have created a crude over-lay method.  My problem is every time I draw the small object and do my simple overlay trick; I loose what I was rendering to the back buffer, the new updated main, complex scene. Is there a better way of doing this overlay? Pbuffers maybe?  I read overlays were built into certain super high end video cards, but this is not an option for me.  Thanks for any help.   
Quote:My problem is every time I draw the small object and do my simple overlay trick; I loose what I was rendering to the back buffer, the new updated main, complex scene. What do you mean lose it? Is it not still in the texture you copied it to?/edit Do you mean that in one thread you are constantly updating the main scene and copying it to a texture, and in another you are using that texture as the background of the main render, over which you render other objects?   ;  render the unchanging scene into a (rectange perhaps) texture (preferably with FBO)and each frame draw the texture first on a fullscreen quad+ then draw whatever u want over the top of it.also there is an extension (buffer_region or something) that lets u save the screen somewhere but the texture method is better   ;  Thanks for the replies.   