title: Issue with drawing half of a sphere in three.js
body: <p>I'm creating a skydome in three.js like this:</p>
  
  <pre><code>var geometry = new THREE.SphereGeometry( 40, 32, 15, 1*Math.PI/2, 2*Math.PI, Math.PI, Math.PI);
  var material = new THREE.MeshBasicMaterial( { color: 0xddddff } );
  mesh = new THREE.Mesh( geometry, material );
  mesh.material.side = THREE.DoubleSide;
  scene.add( mesh );
  </code></pre>
  
  <p>This does draw half of a sphere but it also colors the part that I expected to be open (it colors the surface of my mesh that I need the skydome for). How do I solve this problem?</p>