17
17
* Because the starting point of a segment is also the ending point of the previous, only one must be used.
18
18
* And we do no use twice the same segment, so we do NOT use both starting and ending points of these 2 segments.
19
19
* So we must use only one ending point of each segment when calculating intersections
21
21
* Here, the ending point above the Y reference position is used
22
22
* and the ending point below or equal the Y reference position is NOT used
23
23
* Obviously, others cases are irrelevant because there is not intersection.