<div dir="ltr"><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">The offset curve implementation is quite complex, so this could be a challenge to debug. The code uses overlay (</span><code style="box-sizing:border-box;font-family:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;font-size:11.9px;padding:0.2em 0.4em;margin:0px;border-radius:6px;color:rgb(36,41,47)">SnapOverlayOp</code><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">), so my first suspicion is that the change to OverlayNG in 3.9 has something to do with this. But not sure why or how </span><code style="box-sizing:border-box;font-family:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;font-size:11.9px;padding:0.2em 0.4em;margin:0px;border-radius:6px;color:rgb(36,41,47)">SnapOverlayOp</code><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"> would have been affected.</span><br><div><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"><br></span></div><div><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">It will be useful to add </span><code style="box-sizing:border-box;font-family:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;font-size:11.9px;padding:0.2em 0.4em;margin:0px;border-radius:6px;color:rgb(36,41,47)">offsetCurve</code><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"> to </span><code style="box-sizing:border-box;font-family:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;font-size:11.9px;padding:0.2em 0.4em;margin:0px;border-radius:6px;color:rgb(36,41,47)">geosop</code><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"> to allow testing across versions.</span><span style="color:rgb(36,41,47);font-family:-apple-system,system-ui,"Segoe UI Variable","Segoe UI",system-ui,ui-sans-serif,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"><br></span></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Sep 9, 2021 at 4:26 PM Nyall Dawson <<a href="mailto:nyall.dawson@gmail.com">nyall.dawson@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi list,<br>
<br>
Apologies for bringing up a bug report on the mailing list, but I'd<br>
love to get some more feedback on a rather scary regression I've found<br>
on recent GEOS versions (<a href="https://github.com/libgeos/geos/issues/477" rel="noreferrer" target="_blank">https://github.com/libgeos/geos/issues/477</a>)<br>
<br>
In a nutshell, certain simple single-part linestrings magically become<br>
multi-part linestrings with gaps in them after offsetting the curves.<br>
<br>
Is there anyone interested in fixing this? If so, can you please send<br>
me an estimate of the cost of this fix?<br>
<br>
Thanks!<br>
Nyall<br>
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</blockquote></div>