void roundStart()
{
// 开始新的一轮
roundHasStarted = true;
timeAfterRoundStart = 0;
UFOController[] ufoCtrlArr = UFOfactory.produceUFOs(difficultyManager.getUFOAttributes(), difficultyManager.UFONumber);
for (int i = 0; i < ufoCtrlArr.Length; i++)
{
ufoCtrlArr[i].appear();
}
actionManager.addRandomActionForArr(ufoCtrlArr, ufoCtrlArr[0].attr.speed);
}