title: How to use Three.js plane
body: <p>I'm trying to use three.js plane to get the distance from a point to a plane. </p>
  
  <p>I have three points a,b,c, that I calculate the normal like so: </p>
  
  <pre><code>    const v = a.clone().sub(c);
      const u = b.clone().sub(c);
      const normal = u.cross(v);
  </code></pre>
  
  <p>Then </p>
  
  <pre><code>const plane = new THREE.Plane(normal, (?))
  </code></pre>
  
  <p>What are you supposed to give in the second argument? </p>
  
  <p>From the <a href="https://threejs.org/docs/#api/math/Plane" rel="nofollow noreferrer">docs</a>: </p>
  
  <blockquote>
    <p>the negative distance from the origin to the plane along the normal vector. Default is 0.</p>
  </blockquote>
  
  <p>What does that mean?</p>
  
  <p>If I place there the distance of one of the points a,b,c to (0,0,0) (positive and negative distance), like <code>const dist = a.distanceTo(new THREE.Vector3(0,0,0))</code>, then if I do:</p>
  
  <pre><code>plane.distanceToPoint(a); 
  </code></pre>
  
  <p>I'm getting a huge number and not zero, the same happens if I leave that argument empty.</p>
  
  <p>So how can I place that plane at its correct place so that the distance to points on that plane will be zero as it should?</p>