[mkgmap-dev] mkgmap ToDo list

Thu Apr 17 06:42:56 BST 2014

Hi Henning,

okay. I think WanMil told me that before, but I forgot again ... 

A few details:

mkgmap always reversed routable ways with oneway=-1 or oneway=reverse after style processing.

With r2944 I've changed the code so that this happens before calling RoadMerger and also that overlaying 
lines are reversed.

If I got that right, the style may use different types for overlaying lines, depending on the oneway tag,
so if you use the same style for r2943 or older and for current version, you should see a difference
for oneway=-1 ways.
I don't know how difficult it is to change the style to produce correct results with current version again,
but you have to remember that the way is reversed, so left will be right, forward will be backward.

I see two alternatives:
1) mkgmap reverses the way before style processing. This requires also to reverse all tags like
bicycle:left, car:forward etc, so it is not trivial. On the other hand, it might allow to merge more 
roads in RoadMerger.
2) mkgmap makes sure that overlaying lines are NOT reversed. I think this can be done
with the attached patch.

By the way:  There are also tags on nodes which depend on the direction of the way, see
http://gis.19327.n5.nabble.com/direction-forward-backward-on-nodes-tt5803072.html

I think we can ignore this because in the points file you can't detect the direction of the way.

Gerd
Date: Wed, 16 Apr 2014 23:00:35 +0200
From: osm at aighes.de
To: mkgmap-dev at lists.mkgmap.org.uk
Subject: Re: [mkgmap-dev] mkgmap ToDo list

    Am 16.04.2014 22:01, schrieb GerdP:

      Why do you think that it is a bug?

    Think
        about oneway=-1 and in style you add oneway-arrows (link mapnik
        does). In style you will handle -1 special, because arrows
        should drawn in oposite direction of way. If mkgmap now changes
        direction of the way, arrows should be in wrong direction, or am
        I wrong?

        Henning

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