title: Is there a way to clear a non-rectangular area in a canvas element?
body: <p>Using javascript, I've drawn several polygon images on my canvas.  </p>
  
  <p>I'd like to, based on user events/clicks, be able to clear a section of the canvas (one of those polygon images), which is an irregular shape, not a rectangle.</p>
  
  <p>So, I cannot use clearRect() for my purpose.</p>
  
  <p>Can anyone think of a way I can do that?</p>
  
  <p>Essentially, I'd like to make a portion of my canvas transparent, but it is not a rectangular shape...  Once I have an area defined with which I can fill() and stroke(), can I not also clear() it...  I know that such a function is not available.  What are folks doing to clear <strong>irregularly shaped</strong> sections?</p>
  
  <p>I'm a little new to this, so apologies in advance if this sounds like a silly question.</p>