[mkgmap-dev] patch: improve RoadMerger: allow to merge roads with reversed points

Wed May 5 15:46:27 BST 2021

If the direction of a line is changed, will all lines created via continue
also be changed? If yes then this decreases the lines a lot where I would
need the special tag. If not it will get complicated...
Well and the patch itself so far only saved about 0.3% of total map size.
Better than nothing for no visual impact of course.

On Wed, 5 May 2021 at 22:43, Gerd Petermann <gpetermann_muenchen at hotmail.com>
wrote:

> Hi Felix,
>
> no idea why you talk about waterways here. The thread is about a patch for
> RoadMerger. As the name suggest this code merges roads, nothing else.
> RoadMerger considers far more attributes of lines compared to the simple
> LineMerger, not just the type and name but also all the attributes which
> affect routing.
> It will not merge oneways with opposite direction, nor does it merge roads
> which are used in restrictions.
>
> My current approach is to implement the new special
> mkgmap:has-direction=true
> If the style sets this for a road or any of its overlay lines RoadMerger
> should not reverse the road.
>
> Gerd
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> Felix Hartmann <extremecarver at gmail.com>
> Gesendet: Mittwoch, 5. Mai 2021 13:04
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] patch: improve RoadMerger: allow to merge roads
> with reversed points
>
> Actually when I think about it - reversing the direction for waterways
> should be done anyhow - there is no waterway that flows in opposite
> direction. Cliff lines most likely the same.
> And for lines that are off center - that doesn't matter as long as all
> resulting lines are reversed. It would actually be better as otherwise at
> one point the right side jumps to the left and this could be prevented.
>
> Yes oneway roads (plus all copies created from it via continue) - those
> you cannot merge.
>
> On Wed, 5 May 2021 at 18:47, Felix Hartmann <extremecarver at gmail.com
> <mailto:extremecarver at gmail.com>> wrote:
> will that patch also work on the low resolution branch, or only against
> trunk?
>
> On Wed, 5 May 2021 at 18:05, Gerd Petermann <
> GPetermann_muenchen at hotmail.com<mailto:GPetermann_muenchen at hotmail.com>>
> wrote:
> Hi all,
>
> up to now RoadMerger doesn't merge (combine) two roads if the have
> different directions. This is OK for oneway roads but I see no need for
> this with other roads. The attached patch changes this. It has an influence
> on file size (safes a few KB in each tile) and very likely also on routing,
> hopefully to the better/faster.
> It also reduces zig-zagging in the low-res-opt branch.
>
> Strangely enough almost all was already implemented, so maybe WanMil (the
> original author) tried that before and found a reason not to do it. Will
> search the archives later...
>
> Gerd
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>
>
> --
> Felix Hartman - Openmtbmap.org & VeloMap.org
>
>
>
> --
> Felix Hartman - Openmtbmap.org & VeloMap.org
>
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> mkgmap-dev at lists.mkgmap.org.uk
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>

-- 
Felix Hartman - Openmtbmap.org & VeloMap.org
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