title: Modify vertices in a THREE.BufferGeometry object
body: <p>I need to selectively show/hide 1000+ lines of different sizes, positions and colors.</p>
  
  <p>My first attempt made a THREE.Geometry with a name for each. To hide/show I iterate over scene and hide/show on each based on name and my heuristic. That seemed very slow - around 50Hz for ~1000 lines.</p>
  
  <p>I made a test using a similar approach but using only a single THREE.Geometry to hold all of the lines. That was much faster but of course but I can only apply one material to all the lines which is no good. I was able to set the right flags and update the positions of the lines while the app was running though.</p>
  
  <p>The best approach seems to be to use THREE.BufferGeometry. I made a test which was very fast and worked as expected for the initial set up but I was unable to change the position/visibility and color of each line afterwards. I made a JS fiddle that illustrates it - <a href="http://jsfiddle.net/SSnKk/">http://jsfiddle.net/SSnKk/</a> - but calling <code>buffer_geometry.dynamic = true;</code> and <code>buffer_geometry.verticesNeedUpdate = true;</code> didn't appear to help.</p>