title: Three.js particles to form a shape
body: <p>I've been following this tutorial (<a href="http://creativejs.com/tutorials/three-js-part-1-make-a-star-field/" rel="nofollow">http://creativejs.com/tutorials/three-js-part-1-make-a-star-field/</a>) and everything is going fine, but I'd like to know how I can modify the script so then there's some form of callback when the particle reaches the end.  I've modified the code in the tutorial so it's reversed the way the particles are moving.</p>
  
  <p>What I'm wanting to try and create is a load of particles coming together to form a square, is it possible from using the code in the tutorial as a start and build on top of that or should I look elsewhere and start over?</p>
  
  <p>Thanks in advance.</p>