[geos-devel] Intersection result ordering change between 3.7.1 and 3.9.0

[Andrew Hershberger]

Thanks for the replies.

Re: the order of the intersection points. the only difference in the output
from the example they shared was that there were 3 multilinestrings, each
of which contained 2 linestrings which were ordered differently.

Let's see whether normalize solves this for them.

Andrew

On Wed, Jan 6, 2021 at 7:36 PM Paul Ramsey <pramsey at cleverelephant.ca>
wrote:

>
>
> > On Jan 6, 2021, at 5:31 PM, Andrew Hershberger <
> andrew.d.hershberger at gmail.com> wrote:
> >
> > A GEOSwift consumer noticed some differences in intersection behavior
> between geos 3.7.1 and 3.9.0. I'm guessing this is related to OverlayNG?
> https://github.com/GEOSwift/GEOSwift/issues/212
>
> Yes, component ordering in collections, ring start/end points, interior
> ring ordering, it's all potentially changed in 3.9 with the NG overlay. You
> can retain tests that work across new/old versions by applying the
> GEOSNormalize() function to everything, to get a deterministic ordering of
> rings/components/start points etc.
>
> > I'm looking for guidance on how to advise them w.r.t. their statement
> that they're relying on "the order of the intersection points". Is that
> part of the contract such that changes should be considered breaking?
>
> Not sure what that means, maybe they are intersecting lines and getting
> points? Would need to know the precise use case to know if it's something
> we used to try and preserve.
>
> P.
>
>
>
> >
> > Andrew
> > _______________________________________________
> > geos-devel mailing list
> > geos-devel at lists.osgeo.org
> > https://lists.osgeo.org/mailman/listinfo/geos-devel
>
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