void Update()
    {
        //当退出按下时
        if (Input.GetKeyDown(KeyCode.Escape))
        {
            if (gamestate == Util.GameState.gaming)
            {
                SetGameState(Util.GameState.pause);
                showPauseLayout();
                pauseGame();
            }
            else
            {
                SetGameState(Util.GameState.gaming);
                hidePauseLayout();
                backToGame();
            }
        }

        gameControl.Update();
    }