title: Three.js load separated object
body: <p>My object separated into 9 files, so I need to load all 9 files: file_1.obj, ..., file_9.obj, merge them all and after that somehow use file.mtl with the result "big" object. How am I suppose to do it?</p>
  
  <p>I thought about this solution:</p>
  
  <pre><code>mainObjGeometry = new THREE.Geometry();
  loader.load( 'file_1.obj', function ( object ) {
      object.updateMatrix();
      mainObjGeometry.merge(object.geometry, object.matrix);
  });
  ...
  loader.load( 'file_9.obj', function ( object ) {
      object.updateMatrix();
      mainObjGeometry.merge(object.geometry, object.matrix);
  });
  </code></pre>
  
  <p>And after that load .mtl file and connect them (even though I don't know how to do it).</p>
  
  <p>But I think that using this technique I can not know the time when all objects are loaded.</p>
  
  <p>How can I solve this problem? And can I connect "mainObjGeometry" and loaded from .mtl "mainObjMaterial"?</p>