title: Intermittent semi-transparent sphere in Three.js
body: <p>I would like somebody to explain me how I can achieve the blue semi-transparent intermittent sphere of this example: (the one next to the intermittent red sphere)</p>
  
  <p><a href="http://threejs.org/examples/webgl_materials.html" rel="nofollow">http://threejs.org/examples/webgl_materials.html</a></p>
  
  <p>I believe in first place that this is a matter of using the right material with the right settings (specially because the example is about materials) but not sure anyway.</p>
  
  <p>Hopefully you do not feel my question does not deserve to be made here. I was trying to analyze it but definitely it is written in a non-friendly way  for newbies, and I've not been able to separate this part from the rest, not I find an explanation anywhere else.</p>