[geos-devel] strange behavior with offsetCurve, resulting points get resorted

Swen Zanon swen.zanon at geoglis.de
Sun Oct 13 23:51:05 PDT 2013

i am using GEOS (3.4.x) with PHP.
Sometimes i get a strange resorting of the points in a linestring after 
using the offsetCurve-function.
Here is an example:
$geosWKTReader = new GEOSWKTReader;
$geom = $geosWKTReader->read( "LINESTRING(350 100,250 200,400 200,350 
$newGeom = $geom->offsetCurve(-7.5);
die( $newGeom->__toString() );
the result is:
LINESTRING (268.1066017177982 192.5, 347.9453639621833 
112.6612377556149, 387.8647450843758 192.5, 268.1066017177982 192.5)
i would expect something like this:
LINESTRING (347.9453639621833 112.6612377556149,...)
Can somebody tell me, why is it so? Or is it a bug?
The sequence of the points is very important for me, so is there a 
possibility to  prevent this behavior? Maybe by setting a parameter?
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