title: How to add a button in a three js 3d .dae object
body: <p>I have imported a .dae file and added it to my scene. It is hosted here, as I couldn't host in codepen : <a href="http://freelancer.ueuo.com/threejs/" rel="nofollow noreferrer">http://freelancer.ueuo.com/threejs/</a> .</p>
  
  <p>I want to add a button at the Front part of the stall, which says "CLICK ME" for example(designed by css) and then when I click the button I want a popup to appear. I know how to make the popup appear. But I have no idea how to add the button in the scene and use the raycaster to detect it. Please help.</p>