title: Do you have to call glViewport every time you bind a frame buffer with a different resolution?
body: <p>I have a program with about 3 framebuffers of varying sizes. I initialise them at the start, give them the appropriate render target and change the viewport size for each one.</p>
  
  <p>I originally thought that you only had to call <code>glViewport</code> only when you initialise the framebuffer, however this creates problems in my program so I assume that's wrong? Because they all differ in resolution, right now when I render in each frame I bind the first framebuffer, change the viewport size to fit that framebuffer, bind the second framebuffer, change the viewport size to fit the resolution of the second framebuffer, bind the third framebuffer, change the viewport size to fit it, then bind the window frame buffer and change the viewport size to the resolution of the window.</p>
  
  <p>Is this necessary, or is something else in the program to blame? This is done every frame, so I'm worried it would have a slight unnecessary overhead if I don't have to do it.</p>