[mkgmap-dev] Line direction flag, merging etc

Tue May 18 16:51:35 BST 2021

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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