wallEndPoints function
All six of w's points (spec 11 D4), in (k, side) order: k = 0
then 1; left, centre, right.
Implementation
List<(int, WallSide, Vector2)> wallEndPoints(
WorldWall w, List<WorldWall> others) =>
[
for (final k in const [0, 1])
for (final side in WallSide.values)
(k, side, wallEndPoint(w, others, k, side)),
];