[mkgmap-dev] Multipolygon artificial tagging

Mon Feb 22 19:23:09 GMT 2010

> Moin,
>
> I tried a slightly modified patch provided by WanMil, where also mkgmap:mp_*=no
> tags are added:
>
>> the patch for the mp code does not remove any tags from the source
>> polygons and lines. Instead it tags all mp-source lines and polygons
>> with mkgmap:mp_source=yes and mkgmap:mp_created=no.
>>
>> All artificially created polygons during the mp processing are tagged
>> with mkgmap:mp_created=yes and mkgmap:mp_source=no.
>>
>> Example:
>> Polygon A - natural=water, role=outer
>> Polygon B - landuse=grass, role=inner
>>
>> Result after mp processing
>> Polygon A - natural=water, role=outer, mkgmap:mp_source=yes
>> Polygon B - landuse=grass, role=inner, mkgmap:mp_source=yes
>>
>> Polygon A1 - natural=water, mkgmap:mp_created=yes
>> Polygon A2 - natural=water, mkgmap:mp_created=yes
>> Polygon B1 - landuse=grass, mkgmap:mp_created=yes
>
> With this patch I was able to fix the multipolygon borders commonly used in
> Germany, by modifying my style as follows.
>
> For the border lines I don't want to have the artificially created polygons, I
> am only interested in the original polygons from the multi-polygon. So I added
> to each border check the condition mkgmap:mp_created!=yes. As a result only the
> original polygons from a multi-polygon are drawn as borderlines as well as all
> lines not belonging to a multi-polygon.
>
> The second change was done in the polygon files. Here I added to every check the
> condition mkgmap:mp_created!=no. As a result only the artificially created
> polygons are drawn as areas as well as all polygons not belonging to a
> multi-polygon.
>
> So in my eyes with this patch the multi-polygon processing is much better
> controllable via the style file. But you have to adjust your style accordingly,
> so that you do not output both polygons, the original and the artificial one.
>
> Gruss
> Torsten

Torsten,

thanks for testing the patch!

I am a bit unhappy about the fact that the mkgmap:mp_created!=no must be 
added to each rule. Isn't there a rule like
mkgmap:mp_created!=no [break]
which breaks (polygon) processing if the artificial tag is not set?

WanMil