title: THREE.js How to choose a specific surface from a box geometry?
body: <p>I have a question regarding THREE.js.</p>
  <p>I want to choose a specific surface from a box and then use it to detect a collision with a ball. The question is that I don't know how to choose that face. I have checked all the methods from three.js and none of them is useful. I am not sure whether there is another way to choose a specific face.</p>
  <p><strong>Surface and Ball</strong></p>
  <p><img src="https://i.stack.imgur.com/r99LS.png" alt="Surface and Ball" /></p>
  <pre><code>const hand1geo = new THREE.BoxGeometry(2, 0.01, 0.2);
  const material_sidehand = new THREE.MeshBasicMaterial({ color: 0x3cc1b7 });
  const sidehand = new THREE.Mesh(hand1geo, material_sidehand);
  </code></pre>
  <p>Above is how I created the box.</p>