title: three.js BoundingBoxHelper without diagonals
body: <p>My BoundingBox is like : <a href="http://i.stack.imgur.com/IGmxF.png" rel="nofollow">http://i.stack.imgur.com/IGmxF.png</a> and I don't want to show the triangles inside the box, how can I remove those lines? Thanks.</p>
  
  <pre><code>    var bbox = new THREE.BoundingBoxHelper(object3d, new THREE.Color(0xFF9900));
      bbox.visible = false;
      bbox.name = "BBOX"
      bbox.update();
  
      object3d.children[0] = bbox;
  
      scene.add(bbox);
  </code></pre>