private void startDisplayLoop() {
    while (!Display.isCloseRequested()) {
      GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);

      checkInput();
      applyPhysics();

      drawStuff();

      endThisLoop();
    }
    endProgram();
    Display.destroy();
  }
 private void endProgram() {
   GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
   System.exit(0);
 }