title: threejs: rendering multiple scenes in a single webgl renderer
body: <p>I am trying to include multiple scene into a single webgl renderer as per code below:</p>
  
  <p>renderer.render( scene1, camera );<br>
  renderer.render( scene2, camera );  </p>
  
  <p>I am facing issue where in the last scene object that is passed to the renderer is being painted and the previous one is not. I confirmed it by swapping the above two lines of code. I am newbie to threejs and would like to know if the above can be achieved? and also if you can guide me towards supporting examples (if any).</p>
  
  <p>Thanks! </p>