title: How to scale a shape made of points?
body: <p>Say I have a shape like this:</p>
  
  <p><img src="https://i.stack.imgur.com/gVLTN.png" alt="larger shape"></p>
  
  <p>And I want to scale it down to this:</p>
  
  <p><img src="https://i.imgur.com/KIYhTSj.png" alt="smaller shape"></p>
  
  <p>How do I calculate the location of the points (red circles) to do so?</p>