title: THREE.JS displacement map not affecting shadows
body: <p>I'm struggling with getting the shadows working correctly with a displacement map. I've looked the problem up on Google and as far as I understand, the displacement map distorts the vertices. So in theory there shouldn't be a problem.</p>
  <p>However, the displacement map has no effect on the shadows.
  <img src="https://i.stack.imgur.com/aN6Tf.png" alt="image of the problem" /></p>