[geos-devel] Order of results in GEOSDelaunayTriangulation

[Nyall Dawson]

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
triangulation?

Nyall