OpenGL Lights

procedure setupLighting;
  const light_position: array [0..3] of GLFloat = (0.0, 0.0, -scene_distance, 1.0);
        light_direction: array [0..2] of GLFloat = (0.0, 0.0, -1.0);
        light_color: array [0..3] of GLFloat = (0.5, 0.5, 0.5, 1.0);
        light_cutoff: array [0..0] of GLFloat = (180.0);
        light_exponent: array [0..0] of GLFloat = (50.0);
begin
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);

  glLightfv(GL_LIGHT0, GL_POSITION, light_position);
  glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, light_direction);
  glLightfv(GL_LIGHT0, GL_SPOT_CUTOFF, light_cutoff);
  glLightfv(GL_LIGHT0, GL_SPOT_EXPONENT, light_exponent);
  glLightfv(GL_LIGHT0, GL_SPECULAR, light_color);

  glEnable(GL_COLOR_MATERIAL);
end;