Ports geometry/planar/Polygon.java (corner de-duplication and collinear
removal, winding number) and PolygonShape.java, including the recursive
split_to_convex that decomposes a simple polygon into convex Simplex
tiles by dividing at concave corners along minimal axis-parallel lines.
Orientation and convexity tests are exact; the division-point search is
approximate (float line evaluation, split point rounded to an integer
corner) as upstream. The concave-corner search starts deterministically
at corner 0 rather than a seeded PRNG; this only affects which valid
decomposition is produced.
Supporting additions: Simplex.from_corners (convex polygon to simplex)
and Line.function_value_approx / function_in_y_value_approx.
Invariant tests over L, plus, staircase and square polygons: tile areas
sum to the polygon area (no gaps, no overlap), a point is in the polygon
iff in some tile, and no point is strictly inside more than one tile
(interiors disjoint). Also covers Polygon normalization and orientation.
Ryan Malloy
68ab16a7cf