title: Three.js skinned animation mesh disappears when material skinning is true
body: <p>I've exported an animated model from Blender which doesn't seem to have any issue instantiating. I'm able to create the <code>THREE.Animation</code> and model, but I was finding there was no animation. I realized I needed to set <code>skinning</code> true on each material, but when I do that the entire mesh goes missing.</p>
  
  <p>Below is my (quick and messy) code trying to get everything to work. </p>
  
  <pre><code>function loadModel() {
          var loader = new THREE.JSONLoader();
          loader.load('assets/models/Robot.js', function(geom, mat) {
              _mesh = new THREE.Object3D();
              _scene.add(_mesh);
  
              geom.computeBoundingBox();
  
              ensureLoop(geom.animation);
              THREE.AnimationHandler.add(geom.animation);
  
              for (var i = 0; i &lt; mat.length; i++) {
                  var m = mat[i];
                  //m.skinning = true; &lt;-- Uncommenting this makes the model disappear
                  //m.morphTargets = true; &lt;-- This causes all sorts of WebGL warnings
  
                  m.wrapAround = true;
              }
  
              var mesh = new THREE.SkinnedMesh(geom, new THREE.MeshFaceMaterial(mat));
              mesh.scale.set(400, 400, 400);
              mesh.position.set(0, -200, 0);
              mesh.rotation.set(Utils.toRadians(-90), 0, 0);
              _mesh.add(mesh);
              _robot = mesh;
              Render.startRender(loop);
  
              var animation = new THREE.Animation(mesh, geom.animation.name);
              animation.JITCompile = false;
              animation.interpolationType = THREE.AnimationHandler.LINEAR;
              animation.play();
  
          });
      }
  </code></pre>
  
  <p>I believe I'm updating the AnimationHandler correctly in my loop</p>
  
  <pre><code>function loop() {
      _mesh.rotation.y += 0.01;
  
      var delta = 0.75 * _clock.getDelta();
      THREE.AnimationHandler.update(delta);
  } 
  </code></pre>