title: How to create progress bar in sprite kit?
body: <p>I want to create my own progress bar in Sprite Kit.<br>
  I figured I will need to images - one fully empty progress bar and filled progress bar.<br>
  I have those images, I put filled one on top of empty one, they are regular <code>SKSPriteNodes</code> now I can't figure out how do I cut my filled image where I need?  </p>
  
  <p>How do I cut SKSpriteNode image at certain point? Maybe texture?</p>