title: How do "scroll journey" webpages work
body: <p>I'm sorry if this has been asked previously, I really wasn't sure how to word this question. Here's <a href="http://space.angrybirds.com/launch/" rel="nofollow">one popular example</a>, <a href="http://www.google.com/green/storyofsend/desktop/" rel="nofollow">and another</a> of what I mean, where when the user scrolls down the page and the page itself actually pans over a scene in a fixed path that needn't be the direction of the scroll at all.</p>
  
  <p>How do these sites work?</p>