User Panel: Lines 2
... Bundled into a...
Tool: PolysectLine[A, u, 4, Pts]
where Pts = {pnl1, pnl2, pnl3, pnl4, pnl1} (The vertices of the Panel in a closed loop).
...gives the points of intersection of
Line[A, u]: The line through A with direction u,
Polygon[Pts]
...and the intervals (segments) which lie inside the polygon.
