Dan,
Just commenting on your last question. I don't think using function
pointers is feasible. I've vague memories of past times where I tried
this and I remember that at least on Windows, with shared libraries, the
address of a function inside the library is not the same as the address
an external user gets, due to how the dynamic loader works (typically
the address an external user gets is the one of some "trampoline"
function that then jumps to the actual address inside the library)
Even
Le 07/01/2026 à 16:06, Daniel Baston a écrit :
Hi,
I have been incrementally adding curve support in GEOS, for example in
https://github.com/libgeos/geos/pull/1347. I've been thinking about
the best way for applications such as QGIS/PostGIS/GDAL to integrate
this functionality.
Currently, these applications linearize all geometries before sending
them to GEOS. That will not be necessary for GEOSNode and a list of
functions that will likely increase over multiple GEOS releases. It
seems cumbersome for applications to rely on GEOS version checks to
know if linearization is needed, so I think GEOS should offer an
ability to automatically linearize inputs and curvify outputs where
needed. The parameters for this conversion (and whether to perform it
all) could be held by the context handle, and controlled with
functions like GEOSContext_setCurveToLine([ DISABLED / STEP_DEGREES /
MAX_DEVIATION ]) and GEOSContext_setLineToCurve([ DISABLED /
SOME_OTHER_TOLERANCE]). I would also expose a
GEOSCurveToLine(GEOSGeometry*, params) and
GEOSLineToCurve(GEOSGeometry*, params).
If needed, we could also provide a capabilities function that would
take a function name (or pointer?) and report whether the function
supports curves in the current GEOS version.
Does this seem like a reasonable approach?
Dan
--
http://www.spatialys.com
My software is free, but my time generally not.
