union: tried to create degenerate segment.

[pentacular]

const a = [[[0.17283,18.40241],[0.22772,18.48456],[0.22772,18.48461],[0.17281,18.40243],[0.17283,18.40241]]];
const b = [[[0.11978,18.32302],[0.14685,17.90202],[0.15809,18.11877],[0.11978,18.32302],[0.11978,18.32306],[0.11978,18.32302]]];
polygonClipping.union(a, b);

produces

"Tried to create degenerate segment at [0.11978, 18.32302]"

Which is a bit odd, because the two shapes don't overlap.

[mfogel]

Ah, nice. Thank you for the bug report @pentacular I've reproduced the failure on my side with the latest on master.

One of those two polygons is really thin, I would assume that's what's prompting the library to barf. It's trying to create a segment from [0.11978, 18.32302] to [0.11978, 18.32302], and there's a check in there to avoid creating of zero-length segments.... that's what's throwing the error.

Do you have a preference as to which of the bugs you've reported I look at first? Cheers.

[pentacular]

Thanks for looking into it. :)

Either order is fine by me.

[pentacular]

I wonder if an option to drop zero length segments would be reasonable?

[mfogel]

Good thought - the library already does try to drop zero length segments by default. What was going on here was one of the input polygons has an infinitely thin 'peninsula' sticking off one of its vertices. The algorithm was getting confused trying to trim this off.

Thanks for the bug report, appreciate it!