title: Normalized Device Coordinates
body: <p>I'm writing a library that deals with 2D graphical shapes.</p>
  
  <p>I'm just wondering why should my coordinate system range from <strong>[-1, 1]</strong> for both the x and y axis
  <img src="https://i.stack.imgur.com/WNfIA.png" alt="enter image description here"></p>
  
  <p>instead of <strong>[0, width]</strong> for x and <strong>[0, height]</strong> for y ?
  <img src="https://i.stack.imgur.com/RLMOg.png" alt="enter image description here"></p>
  
  <p>I went for the latter system because I felt it was straight forward to implement.</p>