title: How to determine if a list of polygon points are in clockwise order?
body: <p>Having a list of points, how do I find if they are in clockwise order?</p>
  
  <p>For example:</p>
  
  <pre><code>point[0] = (5,0)
  point[1] = (6,4)
  point[2] = (4,5)
  point[3] = (1,5)
  point[4] = (1,0)
  </code></pre>
  
  <p>would say that it is anti-clockwise (or counter-clockwise, for some people).</p>