title: ThreeJS: How to detect if an object is rendered/visible
body: <p>How can I detect, as fast as possible, if a threejs object is visible for the eyes of the camera? The <em>obj.visible</em> attribute is a setter, so not useful. Also <em>frustumCullum</em> is not enough, as it only indicates if an object is out of the camera viewport. I need to know if an object is hidden behind another much larger object.</p>
  
  <p>Anybody has an idea?</p>
  
  <p>Cheers</p>
  
  <p>Markus</p>