title: How can I get the outline of the overlapping patches in matplotlib without maths
body: <p><a href="http://matplotlib.org/examples/pylab_examples/ellipse_rotated.html" rel="nofollow">http://matplotlib.org/examples/pylab_examples/ellipse_rotated.html</a>.</p>
  
  <p>I want to add lines along the outline of the overlapped area (the quasi-polygon) of those patches as shown in the above example. 
  How can I achieve this without solving equations?</p>