title: How to merge two GLKViewControllers
body: <p>I have two controllers using OpenGL views:</p>
  
  <ol>
  <li>uses AVFoundation to acquire video frames to process + displays them
  with OpenGL ES (the video acquiring process cannot stop)</li>
  <li>displays a set of points in an OpenGL ES view</li>
  </ol>
  
  <p>At the moment when I want to switch to the second controller I do it like a semi-transparent modal popup. This is clunky and the phone has to render 2 OpenGL ES full-screen views with transparency as well.</p>
  
  <p>I was thinking of adding a toolbar to switch between these 2 views (possibly 3), and using a single controller in the background. From my understanding I can have one view per controller, which means I will have to put conditionals in the delegate view, that relies on some variables connected to the buttons.</p>
  
  <p>Is this the right choice? Is there any better approach?</p>