title: Drawing a line along z axis in opengl
body: <p>I am trying to draw a line along the point <strong><code>0.5,-0.5,0.0 to 0.5,-0.5,-0.5</code></strong> using <code>GL_LINES</code> in the <strong>z direction</strong> .</p>
  
  <p>Intialization of the window :</p>
  
  <pre><code>glutInitDisplayMode(GLUT_DOUBLE|GLUT_DEPTH|GLUT_RGB);
  </code></pre>
  
  <p>Setup in the display function.</p>
  
  <pre><code>glClearColor(1.0, 0.0, 0.0, 0.0);
  glEnable(GL_DEPTH_TEST);
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glColor3f(0.0, 0.0, 0.0);
  </code></pre>
  
  <p>However, the line is not displayed on the screen. Please help as to how to display a line going along the z direction.</p>