[mapserver-users] algorithm for line offset (-99 value)

[Lime, Steve D (MNIT)]

Hi Peter: The functions you’re looking for are msOffsetPolyline() and msOffsetCurve() in maputil.c. We do use GEOS if it’s available though and fall back to our own code only if necessary.

Steve

From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Peter Maes
Sent: Monday, July 07, 2014 4:32 AM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] algorithm for line offset (-99 value)

Hi,

In the past we only rendered image tiles for roads, where we need the 2 lanes to be drawn separately. For this we've been using the -99 value offset parameter.

However, now we need to use mapserver wfs on the vector side and do this line offset on the client.

Can anyone point me to the right direction on how this is implemented? Unfortunately I can't read c very well so digging in the mapserver source also seems difficult.

Perhaps if I know where to look for?

Given a WKT linestring (either WGS84 or EPSG 900913) how could I offset it a few pixels in direction of the line?

Thanks for any help or pointers.


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