[geos-devel] Order of results in GEOSDelaunayTriangulation

Nyall Dawson nyall.dawson at gmail.com
Mon Sep 4 02:10:27 PDT 2017

On 4 September 2017 at 17:31, Sandro Santilli <strk at kbt.io> wrote:
> On Mon, Sep 04, 2017 at 04:33:28PM +1000, Nyall Dawson wrote:
>> Hi list,
>> Quick question - is there any logic to the order of geometries in the
>> collection returned by calling GEOSDelaunayTriangulation?
>> I'm looking for a way to reliably associate the parts of the returned
>> collection with the original input nodes. Ideally I'd like to avoid
>> having to test for intersection for each of them.
> I don't think there's any promise about output order, so even if you
> find one now it won't necessarely remain.

That's what I suspected. How about geometry user data, could that
potentially be used here?

E.g. if I set the user data for each point geometry being fed into a
multipoint via GEOSGeom_createCollection, could that user data be
retained and then later copied over to the output polygons from the


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