title: Can't make glViewport() to work
body: <p>I'm starting to work in a 2D game, but I don't know the way I'm supposed to use viewPort(). This is my Init() code:</p>
  
  <pre><code>void init(void)
  {
      glClear(GL_COLOR_BUFFER_BIT);
      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      glViewport(100, 100, 800, 600);
      gluOrtho2D(0, 800, 600, 0);
      glMatrixMode(GL_MODELVIEW);
      glLoadIdentity();
      glClearColor(0.0, 0.0, 0.0, 0.0);
  }
  </code></pre>
  
  <p>What I want to know is that, after drawing an image to the window, how can I look only at a part of it, and not the whole world?</p>