一个。检查它是否相交整个cirlce。
B.检查如果是交叉无论是直线段线。
C.如果不是，请检查圆心的夹角在于角度范围段（点积有利于本）。

A. Check if it is intersecting the whole cirlce.
B. Check if it is intersecting either of the straight segment lines.
C. If not, check if the angle between the circle centres lies in the angular range of the segment (dot product is good for this).

路口需要 A和＆放大器; （B || C）