title: Dynamic light in html5 canvas
body: <p>I would like to ask how to make such effects <a href="http://img690.imageshack.us/img690/5263/dynamiclightingrev1.png" rel="nofollow">http://img690.imageshack.us/img690/5263/dynamiclightingrev1.png</a> in HTML5 canvas?</p>
  
  <p>my code TileMap
  <a href="http://imageshack.us/f/12/e2cg.png/" rel="nofollow">http://imageshack.us/f/12/e2cg.png/</a></p>