title: THREE.js: Object3D Size Attenuation
body: <p>Is it possible to turn off sizeAttenuation for an Object3D in THREE.js? </p>
  
  <p>I ask because I'm drawing a trajectory on a very large scale using arrow helper to indicate the direction of motion, and I want the heads of the arrows to stay oriented correctly (unlike using a pointcloud w/ sprite points), but also not shrink/grow as you zoom the camera.</p>
  
  <p>Any other ideas? Can I achieve the same effect using a pointcloud/lines?</p>