參考：

http://www.chenghuixueyuan.com/Articles/detail/id/462.html
https://www.leiphone.com/news/201611/uFt7TgmD6ZtSc6TD.html
http://blog.csdn.net/qq_28268507/article/details/70314844
https://www.cnblogs.com/Sweet-Candy/p/5669815.html
http://blog.csdn.net/zhaokaiqiang1992/article/details/35998821?utm_source=tuicool&utm_medium=referral
http://blog.csdn.net/wenthkim/article/details/52319880
http://blog.csdn.net/cwh1010714845/article/details/78639070
http://news.gamedog.cn/a/20171207/2276788.html

遊戲中的紅點提示設計