[mkgmap-dev] Line direction flag, merging etc

Wed May 19 06:37:03 BST 2021

Hi Ticker,

I didn't notice that overlays are not documented. They appear in doc\styles\files.txt  but it seems this part is commented out, so the text doesn't make it into the pdf.

The major difference with overlays compared to [continue] is the data flow. The lines from overlays where possibly merged/reverse-merged by RoadMerger, they are even processed by the housenumber code. In that way they are better than lines from [continue] : They also have the added number nodes and there are fewer objects while StyledConverter is active, so theoretically they should perform better.

Anyhow, the concept is old and maybe we should even deprecate it.

I've committed your patch with small changes reg. oneway evaluation.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
Gesendet: Dienstag, 18. Mai 2021 17:51
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Line direction flag, merging etc

Hi Gerd (& Minko?)

overlay files are undocumented and probably unused except in
OpenFietsMaps. It is a very restricted way of doing what is now done
with [... continue {with_actions}] or, even simpler, something like:

tourism=camp_site [0x2b03 resolution 24] [0x2b05 resolution 24]

[continue] allows for different resolution ranges, routing attributes
etc and now, with {set mkgmap:has-direction= }, explicit control of
this for each generated line (although see following).

Thinking about my previous suggestion of looking up each overlay copy
linetype to set has-direction, this could be very dangerous in allowing
different merging/filtering behaviour/filtering between all the copies,
so the lines might not overlay each other.

I don't think overlays should be allowed to add any ugliness. The
lineType as given in the rule should be the one that is checked against
--line-types-with-direction. The replacement and all copies should have
the same value for has-direction.

My implementation preserves the existing behaviour. I think it is quite
tidy and it doesn't need another flag in MapLine.

Ticker

On Tue, 2021-05-18 at 15:03 +0000, Gerd Petermann wrote:
> Hi Ticker,
>
> this is getting even more ugly than I expected when I wrote that I
> don't want to support multiple ways to set the flag...
> Whatever we decide there will be lots of confusion :(
>
> With overlay types and --line-types-with-direction it is not clear if
> one has to list the type that is used in the style or one or more of
> those that appear on the "replacement" side.
> The code in the branch only looks at the type used in the style but
> assumes that the user wants only roads to have the dir-flag. There is
> no good reason for this.
>
> So, I think we need a flag in MapLine which stores the info that
> mkgmap:has-direction=no was used  and we have to evaluate the list
> for each generated replacement type.
> The attached patch for the branch should do that.
>
> Gerd
>
>
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Dienstag, 18. Mai 2021 16:13
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Line direction flag, merging etc
>
> Hi Gerd
>
> I had tried it on some in-between version that I think had equivalent
> logic to the patch and it didn't get overridden.
>
> Doesn't the final (or only) lineAdder set it unconditionally for
> oneway
> roads? If I've misread it I'll build and test.
>
> Ticker
>
> On Tue, 2021-05-18 at 14:01 +0000, Gerd Petermann wrote:
> > Hi Ticker,
> >
> > I don't see that oneway forces direction flag when the tag
> > mkgmap:has
> > -direction=no is set in the branch. Did you try it?
> >
> > Gerd
> >
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> > von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> > Gesendet: Dienstag, 18. Mai 2021 15:53
> > An: Development list for mkgmap
> > Betreff: Re: [mkgmap-dev] Line direction flag, merging etc
> >
> > Hi Gerd
> >
> > The code in low-res-opt looks like ignore-oneway-for-lines.patch.
> > The
> > disadvantage of this, as I see it, is that has-direction can't be
> > forced false for one-way roads.
> >
> > I think my version is clearer.
> >
> > Considering substitute lines from /overlays:
> >
> > I had intended that they all (first and duplicates) have the same
> > has
> > -direction value as the original.
> >
> > An alternative is that the first has the original has-direction
> > value
> > and the duplicate set has-direction solely from
> > lineTypesWithDirection.
> >
> > I don't know which is better.
> >
> > Ticker
> >
> > On Tue, 2021-05-18 at 12:35 +0000, Gerd Petermann wrote:
> > > Hi Ticker,
> > >
> > > in the branch I found a solution which doesn't set the direction
> > > flag
> > > for overlay lines when the OSM way is a oneway and a road with
> > > overlay type is created.
> > > With your patch still ALL lines created from the overlay type
> > > have
> > > the direction flag set in that case.
> > > Tested this with the unchanged OFM style without any new options.
> > >
> > > Do you see something wrong in the current branch version r4723?
> > > I think it's clearer.
> > >
> > > Gerd
> >
> > _______________________________________________
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> > mkgmap-dev at lists.mkgmap.org.uk
> > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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