[geos-devel] Writing a wrapper around LibGEOS

[Graham Toal]

On Wed, Mar 8, 2023 at 1:12 PM Martin Davis <mtnclimb at gmail.com> wrote:

> As others have said on this thread, adding curve support to GEOS is likely
> to be a big effort.
>
> My opinion is that to consider an extension of this magnitude, there needs
> to be evidence that this initiative is feasible and sustainable over the
> long term (at least 10 years). A good way to demonstrate this is a separate
> project that extends GEOS with support for representing curves, and
> implementing a *significant* set of *native* operations on curves.  That
> project should have at least two developers contributing algorithmic code
> to it, to show that there is ability and desire to maintain such complex
> code over the long term.
>

You may find it surprising, but I do appreciate this point of view, and
agree in as much as if I am the only person advocating for it, it's not
going to happen as frankly I'm not "one of us" - I'm not a geographer and
my interest in GEOS is primarily in how far I can stretch it in the
direction of being a generic domain-independent polygon package that could
be used in CAD and other fields. This may not be something you're
interested in and there may not be enough interest in adding curves to the
package from programmers working in the geography field.

And also I agree that a concrete demonstration in terms of a fork or pull
request is a precondition to a more significant effort by the current
maintainers; and I'd be happy to start that myself *if* I were a C++
programmer, but at the age of 65 I honestly do not have the enthusiasm to
learn another language to the depth that I know C, which I think is a
pre-requisite for working on a released codebase in any language.

So I'll continue to potter on working on an interface layered on top of
your package (which is pretty good - the best of all the ones I've looked
at, that support calling from C) and if any of the GEOS developers find
anything I'm working on useful in the future then maybe you'll revisit the
suggestion of adding curves.  I'll drop in infrequently with status updates
- and if they're not welcome or irrelevant, do say so and I'll stop. I'm
pretty thick skinned and won't take offence.

Incidentally I got the code to do the inverse flattening working relatively
well last night.  I thought at first it was producing more Bezier segments
than were needed until I worked out the math that showed that the
elliptical arcs I was reconstituting were literally not possible with a
single Bezier curve. So, progress.

Regards,

Graham
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