[postgis-devel] ST_CurveToLine extended API proposal

[Sandro Santilli]

I've started work on extended functionality for ST_CurveToLine [1]
to allow for specifying max-error instead of segments-per-quadrant [2]
and balancing of output segments [3].

[1] https://postgis.net/docs/ST_CurveToLine.html
[2] https://trac.osgeo.org/postgis/ticket/2464
[3] https://trac.osgeo.org/postgis/ticket/3772

Current API is:

  ST_CurveToLine(geom) -- defaults to 32 segs-per-quadrant
  ST_CurveToLine(geom, integer segs_per_quadrant)

The proposed new API would be:

  ST_CurveToLine(geom geometry,
          tolerance float8 = 32,
          tolerance_interpretation int = 0,
          balanced bool=true)

The tolerance_intepretation parameter could initially
support these values:

  0 - segments per quarter circle
  1 - maximum distance beween segment and curve

Leaving the door open to futher extensions (for example
QGIS also supports "maximum angle between segments").

The default values would also allow for the new signature
to replace the existing ones, so to have a single signature.

Of course the code would then need to perform some consistency
checking, like not accepting a non-integer value as tolerance
when "segments-per-quarter-cirlce" interpretation is requested.

What do you think about the proposal ? 

--strk;