Segment/segment intersections

[simoncozens]

We currently have a line/segment intersection method, which is great, but I think a generic segment/segment intersection trait would be very useful: line/line, line/curve, curve/curve. I have this code in beziers.py and not having it in kurbo is a blocker for me in moving some projects to kurbo.

The only problem is that segment/segment intersections have many gnarly edge cases, and I'm not 100% convinced that my code handles all of them.

[simoncozens]

I have got most of this implemented, leaning on intersect_line for everything apart from the curve/curve intersection case, but I'm having problems terminating the bisection at the right point. (Which I think was a problem with the Python implementation too.)

[tylers-epilog]

Hi Simon.

Is this still being worked on? I'd like to contribute to this library by providing a way to add operators to paths. For example, get the union of two paths, or subtracting filled shapes of one path from another. Intersections between Beziers/line is necessary to do this.

If you have any code that you can provide for a starting point, that would be great. If not, I plan to add the GeoClip intersection algorithm. I have quite a bit of experience in a similar algorithm, BezClip, so I'm not going into this completely blind, but if you have any tips from your past experience on doing this, please let me know

Thanks,
Tyler

[simoncozens]

I implemented it in #199; waiting for review...

[raphlinus]

Ah, I should take a look at that. On quick skim, it looks pretty good. I'm uneasy about adding a new trait, as those are really intended for user-defined curves (think Euler spirals and similar) and I doubt that trait will get implemented for anything other than existing beziers. (See #6 for thoughts). But that's not a showstopper.

If someone else knowledgeable were to go through that code carefully, I'd be happy to approve after another light skim myself.

[StudioLE]

Are there any plans for this issue to be picked up again?

It sounds like @simoncozens implemented a solution in #199

[simoncozens]

#219 supersedes #199.