title: Difference between glOrthof and glViewPort
body: <p>On OpenGL-ES i'm confused on what the difference is between setting   </p>
  
  <pre><code>glOrthof()  
  glViewPort()
  GLU.gluOrtho2D()
  </code></pre>
  
  <p>with it's respective parameters. Since I believe it's all setting the part you can see to the specified coordinates (width, height). Which should I use?</p>