title: How can I get a renderer in a-frame
body: <p>I try to use three.js library in a-frame.<br>
  For example,  </p>
  
  <pre><code>var helper = new THREE.MMDHelper(renderer);
  </code></pre>
  
  <p>I don't know how to get a  renderer in a-frame.</p>
  
  <p>a-scene has a renderer property.<br>
   => <a href="https://aframe.io/docs/0.3.0/core/scene.html" rel="nofollow">https://aframe.io/docs/0.3.0/core/scene.html</a><br>
  but, it's undefined.  </p>
  
  <pre><code>document.querySelector('a-scene').renderer; &lt;= undefined 
  </code></pre>
  
  <p>Please tell me how to get the rendere  </p>