title: How to prevent overdrawing?
body: <p>This is a difficult question to search in Google since it has other meaning in finance.</p>
  
  <p>Of course, what I mean here is "Drawing" as in .. computer graphics.. not money..</p>
  
  <p>I am interested in preventing overdrawing for both 3D Drawing and 2D Drawing.<br>
  (should I make them into two different questions?)</p>
  
  <p>I realize that this might be a very broad question since I didn't specify which technology to use. If it is too broad, maybe some hints on some resources I can read up will be okay.</p>
  
  <p>EDIT:<br>
  What I mean by overdrawing is:</p>
  
  <ul>
  <li>when you draw too many objects, rendering single frame will be very slow</li>
  <li>when you draw more area than what you need, rendering a single frame will be very slow</li>
  </ul>