title: Why OpenGL fog just doesn't appear?
body: <p>This is how I enable fog in OpenGL:</p>
  
  <pre><code>float fog_colour[4] = {1,1,1,1};
  glEnable(GL_FOG);
  glFogf(GL_FOG_MODE,GL_EXP2);
  glFogfv(GL_FOG_COLOR,fog_colour);
  glFogf(GL_FOG_DENSITY,0.5);
  glHint(GL_FOG_HINT,GL_NICEST);
  glFogf(GL_FOG_START,0.1);
  glFogf(GL_FOG_END,100);
  </code></pre>
  
  <p>Every object is in the range 0.1-100, but fog just doesn't appear, what happened? </p>