[OSM-talk] Indiscrimate layering

"Marc Schütz" schuetzm at gmx.net
Sun Dec 21 13:26:59 GMT 2008


> On Sun, Dec 21, 2008 at 1:11 PM, "Marc Schütz" <schuetzm at gmx.net> wrote:
> >> Doesn't layer=-1 mean that something should be 'below' the landuse
> >> polygons when rendering?  So if you have a river at level=-1 on a
> >> landuse=farm, then you will never see the river because it's under the
> >> (default layer=0) ground.
> >>
> >
> > No, landuse isn't a physical feature, but a logical one. Renderers
> should always draw landuse areas below all other things.
> 
> OK, let's use something non-landuse like natural=forest or
> leisure=park as an example then - if you have a forest at layer 0 and
> a stream at layer -1, would you expect to see the stream?
> 

Well, a forest and a park are landuse too, right? Even if not, renderers will still have to treat them as such and draw them below everything else.

> We could also consider a bridge with a forest on top (e.g. I remember
> there being one in Newcastle), which should probably obliterate any
> layer=0 road that goes under the bridge.

Ok, you really found an example where it doesn't work :-P

Even here you could argue that everything that goes under the bridge should be modelled as a (compound) tunnel object, where you would want to draw the roads dashed. But I'm not sure about this one.

Regards, Marc

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