title: Passing colours from JSON file loader into faces
body: <p>I'm programmatically generating a json file to load a mesh, the vertices and faces render fine but I can't figure out how to pass colours through to the faces as well.</p>
  
  <p>Here's the json file that I'm experimenting with:</p>
  
  <pre><code>{
      "metadata" : {
          "formatVersion" : 3
      },
      "materials" : [],
      "vertices" : [-10,10,0, -10,-10,0, 10,-10,0, 10,10,0, -10,10,10,  -10,-10,10,  10,-10,10,  10,10,10],
      "faces" : [4, 0, 1, 3, 0], //or with 0 as the first number for a plain triangle
      "normals": [],
      "colors": [0.5, 0.4, 0.3],
      "uvs": []
  }
  </code></pre>
  
  <p>And loading like so:</p>
  
  <pre><code>loader.load( "js/models/square.js", function(geometry) {
      var material = new THREE.MeshLambertMaterial( {
          faceColors : THREE.FaceColors,
      });
      material.side = THREE.DoubleSide;
  
      var mesh = new THREE.Mesh(geometry, material);
  }
  </code></pre>
  
  <p>My central problem is that I'm stumbling over how the bitmask works, but the FACE_COLOR bit here <a href="https://github.com/mrdoob/three.js/wiki/JSON-Model-format-3.1" rel="nofollow">https://github.com/mrdoob/three.js/wiki/JSON-Model-format-3.1</a> suggests that it should work, any help would be much appreciated... thanks!</p>