[geos-devel] Supporting OGC winding rules for polygons

Heiskanen Mika (FMI) Mika.Heiskanen at fmi.fi
Wed Nov 22 04:49:09 PST 2017


Would it be possible to add support for OGC (v 1.2) winding rules? Currently

normalize() forces polygon exteriors to be clockwise and interiors to be

counter-clockwise. I had a quick look at the C++, and it looks like adding

a new virtual method with a boolean argument would be quite simple to

implement, and would not break the ABI if the flag is not made into an

optional argument with a default value. I did not check the C-API though.

In comparison, writing a free normalize function which would change the

winding rule seems to be quite cumbersome without direct access to the

object internals.


Mika Heiskanen / FMI

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