title: Why I do not see obj and mtl in this A-frame?
body: <p>I am just getting started with a-frame 0.4.0 3d objects, but I think I make something basic wrong.
  I started as I see here: <a href="https://aframe.io/docs/0.4.0/components/obj-model.html" rel="nofollow noreferrer">https://aframe.io/docs/0.4.0/components/obj-model.html</a>
   and I used this model: <a href="http://tf3dm.com/3d-model/wood-texture-created-in-cycles-82780.html" rel="nofollow noreferrer">http://tf3dm.com/3d-model/wood-texture-created-in-cycles-82780.html</a> But this doesn't worked for me. Why? How can I do well?</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
      &lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;objtest&lt;/title&gt;
          &lt;meta charset="utf-8"&gt;
      &lt;/head&gt;
      &lt;body&gt;
      &lt;a-scene&gt;
        &lt;a-assets&gt;
          &lt;a-asset-item id="tree-obj" src="WoodTexture.obj"&gt;&lt;/a-asset-item&gt;
          &lt;a-asset-item id="tree-mtl" src="WoodTexture.mtl"&gt;&lt;/a-asset-item&gt;
        &lt;/a-assets&gt;
        &lt;a-entity obj-model="obj: #tree-obj; mtl: #tree-mtl"&gt;&lt;/a-entity&gt;
      &lt;/a-scene&gt;
  
      &lt;/body&gt;
      &lt;/html&gt;
  </code></pre>