[mkgmap-dev] [PATCH] turn restrictions - alpha code for testing

Mon Feb 23 16:30:29 GMT 2009

Folks,

The attached patch implements the OSM turn restriction relation as described in

 http://wiki.openstreetmap.org/wiki/Relation:restriction

Here's an example that shows multiple relations being used at a junction

 http://www.openstreetmap.org/?lat=50.26386&lon=10.96498&zoom=17

JOSM shows little restriction signs but I think a lot of renderers won't
show anything.

Only "well formed" turn restrictions are handled - i.e. the 'from' and 'to'
ways must terminate at the 'via' node.

Badly formed turn restrictions will yield a (hopefully) useful error
message that includes the OSM id so that you can go find the relation
using JOSM, etc and fix it.

Multiple 'via' members or the 'via' member being a way rather than a node are
not handled. Those variants are not forbidden by the above description but
not encouraged either and I don't, at this time, think there's good reason
to handle them - if you believe otherwise and can present a compelling case
for their inclusion, I will add support for them.

The "except", "day_on/off", "hour_on/off" tags are ignored. I don't
know how to express those constraints in garmin-speak.

The --ignore-turn-restrictions option can be used to disable the feature.

Please test and report success/failure, etc.

Cheers,

Mark

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