title: Is setting the viewport every frame a good idea?
body: <p>I've been reading through a couple of tutorials for OpenGL-ES 2.0, and I noticed they set the viewport (glViewport) each 60Hz frame.</p>
  
  <p>Is it a good idea to do that or is that just done to simplify the examples?</p>
  
  <p>Are there performance penalties if you do that?</p>
  
  <p>This is for iOS currently but aims to be portable to other platforms.</p>