Le buffer de profondeur (Z-Buffer)

    glEnable(GL_DEPTH_TEST);
     ...
     while(1) {
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         get_viewing_point_from_mouse_position();
         draw_3d_object_A();
         draw_3d_object_B();
     }