title: Method in three.js to orthographically display a slice of the scene
body: <p>I have a fairly simple scene rendered using three.js. I am trying to render just a slice of the scene, like an MRI would do.</p>
  
  <p>I have made two versions of the scene for testing purposes.</p>
  
  <ol>
  <li>A perspective version, this is working great</li>
  <li>An orthographic version which should be only a slice of the scene on a given plane</li>
  </ol>
  
  <p>Rendering the orthographic scene is no problem. I have tried to use the clipping plane to capture the slice, but can't get it to work. Either I get a completely white screen or the whole model.</p>
  
  <p>Here is a top-down view of what I am hoping to achieve:</p>
  
  <pre><code>100 *----------------------------------*
      |                                  |
      |                                  |
      |                                  |
      |                                  |
      ####################################  &lt;-- Capture this slice of 100 units width
      |                                  |
      |                                  |
      |                                  |
      |                                  |
   0  *----------------------------------*
      0                                  100
  
  
  
  
  
                      \  /
                       \/
                     CAMERA roughly @ (50, -100)
  </code></pre>
  
  <p>It is entirely possible that I am missing something obvious. My 3D background is decent, but I'm not an expert.</p>
  
  <p>What is the best way to go about this in Three.js / WebGL? What is the best place for the camera to go?</p>
  
  <p>PS: Yes, I am aware that slicing through some primitives will not work well. I am using a model built from lines and points which I expect will slice fairly safely. Cutting objects in half is not too much of an issue for me.</p>