title: What exactly does the d3 clipAngle method do?
body: <p>I am absolutely confused on what the clipAngle method in d3 does. I've poked in the wiki and in the library its self but am not able to put it in plain vanilla English.</p>
  
  <p><a href="https://github.com/mbostock/d3/wiki/Geo-Projections#clipAngle" rel="nofollow">https://github.com/mbostock/d3/wiki/Geo-Projections#clipAngle</a></p>
  
  <p>I see that my orthographic projection gets sliced in half if the clip angle is set to 90.</p>
  
  <p>If set to 180 I see the front and the back of the sphere</p>
  
  <p>Zero I se nothing</p>
  
  <p>So basically I can imagine this as a plane slicing the sphere?</p>
  
  <p>thanks!</p>