/// <summary>
    /// 做加速运动
    /// <para>bullet 敌机子弹</para>
    /// <para>float acce 加速度</para>
    /// <para>float angle 速度方向 or bool useVAngle使用速度方向</para>
    /// <para>bool isAimToPlayer 是否朝向玩家</para>
    /// </summary>
    /// <param name="luaState"></param>
    /// <returns></returns>
    public static int EnemyBulletDoAcceleration(ILuaState luaState)
    {
        EnemyBulletBase bullet = luaState.ToUserData(-4) as EnemyBulletBase;
        float           acce   = (float)luaState.ToNumber(-3);
        float           angle;

        if (luaState.Type(-2) == LuaType.LUA_TBOOLEAN)
        {
            bullet.GetBulletPara(BulletParaType.VAngel, out angle);
        }
        else
        {
            angle = (float)luaState.ToNumber(-2);
        }
        bool isAimToPlayer = luaState.ToBoolean(-1);

        luaState.Pop(4);
        if (isAimToPlayer)
        {
            Vector2 playerPos = PlayerInterface.GetInstance().GetCharacter().GetPosition();
            angle += MathUtil.GetAngleBetweenXAxis(playerPos - bullet.GetPosition());
        }
        bullet.DoAcceleration(acce, angle);
        return(0);
    }