Wrong result for two simple polygons

These are my two simple polygons:

with coordinates:

[[115,96], [140,206], [120,210], [125,250], [80,300]]
[[111,228], [129,192], [309,282]]

And this is the resulting union:

There are no vertical edges, in fact, no two points share the same x-coordinate. I believe the issue here is with the otherInOut property not being correctly computed as these are the sweep events with otherInOut set to true after the subdivision step:

I also tried with the C++ code available online from the original paper, and the resulting union is the same.

[w8r]

I would love to get some help here, I didn’t have time to look at it recently

[abelramos]

@abelramos Until this gets fixed, I have found that adding very small (like 0.0005), pseudorandom values to the coordinates will prevent this. The problem occurs when a point falls exactly on another line. Our app has grid snapping, I can confirm that this happens all the time.

Exactly. I can also confirm it is not related to floating-point arithmetic and/or epsilon values, I tested the implementation with a type for rational numbers, and the issue remains.