title: Rotate camera around object with Three.js
body: <p>I'm displaying an OBJ element with Three.js using WebGlRenderer, now I'd like to allow users to rotate the camera around the object in any direction, I've found this answer:</p>
  
  <p><a href="https://stackoverflow.com/questions/8426822/rotate-camera-in-three-js-with-mouse">Rotate camera in Three.js with mouse</a></p>
  
  <p>But both examples return me errors, the first says that projector is not defined, and I don't know what it means with "projector". I've just a simple camera, the object and some light. 
  The second code says that undefined is not a function.</p>
  
  <p>Does someone know how to get the result I need? </p>