rules : only when there is the point of threading button, and then only in the h...

代码说明：

规则：只能在有纽扣的点穿线，且只能在水平方向或竖直方向穿 线。线可交叉，但有纽扣的点不能交叉连接。-rules : only when there is the point of threading button, and then only in the horizontal direction or vertical direction of threading. Cross-line, but the point Button can cross-connect.