[jts-dev] Parallel Offset!

[Martin Davis <mtnclimb@xxxxxxxxx>]

Ha!  There is *nothing* "simple" about parallel offset curves!   Despite it seeming simple on the surface...  it's an implementation challenge to handle all or even most reasonable inputs.

The closest thing in JTS is the Single-Sided Buffer functionality [1].  But this returns a polygon.  It would be necessary to do something like the line removal approach to turn this into a proper offset curve.

I think GeoTools has some code for this [2] - if you dare to go there.

PostGIS also has this [3].  Probably needs to get added to JTS sometime...  

[1] http://locationtech.github.io/jts/javadoc/org/locationtech/jts/operation/buffer/BufferParameters.html#setSingleSided(boolean)

[2] http://docs.geotools.org/latest/javadocs/org/geotools/geometry/jts/OffsetCurveBuilder.html

[3] https://postgis.net/docs/ST_OffsetCurve.html

On Wed, Oct 10, 2018 at 3:33 PM Simon (SPDBA) Greener <simon@xxxxxxxxxxxx> wrote:

On a related topic, how does one execute a simple parallel offset linestring in JTS?