<div dir="ltr"><div dir="ltr">Thanks for the replies.<div><br></div><div>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.</div><div><br></div><div>Let's see whether normalize solves this for them.<br></div><div><br></div><div>Andrew</div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jan 6, 2021 at 7:36 PM Paul Ramsey <<a href="mailto:pramsey@cleverelephant.ca">pramsey@cleverelephant.ca</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><br>
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> On Jan 6, 2021, at 5:31 PM, Andrew Hershberger <<a href="mailto:andrew.d.hershberger@gmail.com" target="_blank">andrew.d.hershberger@gmail.com</a>> wrote:<br>
> <br>
> 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? <a href="https://github.com/GEOSwift/GEOSwift/issues/212" rel="noreferrer" target="_blank">https://github.com/GEOSwift/GEOSwift/issues/212</a><br>
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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.<br>
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> 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?<br>
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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.<br>
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P.<br>
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> Andrew<br>
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