[geos-devel] CAPI GEOSUnionCascaded

Sandro Santilli strk at kbt.io
Thu Jul 15 13:03:14 PDT 2021

On Thu, Jul 15, 2021 at 11:01:00AM -0700, Paul Ramsey wrote:
> Just stumbled over this old stub, 
> https://github.com/libgeos/geos/blob/main/capi/geos_ts_c.cpp#L1425
> In addition to GEOSUnaryUnion, which calls a cascaded union as required, we have this explicit hook into cascaded polygon union in the C API. It seems a little duplicative, which is not a high crime, but it also has a hidden feature: unlike UnaryUnion which calls the new NG routines in "safe sequence" (try full precision, fall back to gentle snapping, fall back to snap rounding), this CAPI GEOSUnionCascaded call uses the ClassicUnionStrategy, which is to say the *old* overlay functions and the HeuristicOverlay fallbacks (various forms of bit stripping and precision reduction). 
> Question: 
> - just remove this API end point entirely?
> - flip it over to also use NG semantics?
> - don't touch that you fool, it's important to have it as it is!

We never removed any API. Flip it over, I'd say.


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