[Talk-transit] Multiple tracks

Richard Mann richard.mann.westoxford at googlemail.com
Sun Jun 21 17:09:35 BST 2009


No, simpler than that:

tracks=1 => render a single line at all zooms
tracks=2 => render a double line at all zooms
tracks=X => render a multiple line with X tracks at all zooms
tracks=1ofX => render a single line at high zooms, but render as if tracks=X
at medium/low zooms

and though I wouldn't particularly recommend this complication (but there
are circumstances you might want to use it):

tracks=YofX => render as if tracks=Y at high zooms, and as if tracks=X at
medium/low zooms


As an example, if you've got four individual lines next to one another, they
would all be tracks=1of4.


Richard

On Sun, Jun 21, 2009 at 3:00 PM, Jochen Topf <jochen at remote.org> wrote:

> On Sun, Jun 21, 2009 at 07:24:37AM +0200, Cartinus wrote:
> > On Saturday 20 June 2009 22:20:09 Jochen Topf wrote:
> > > Can you think of any software or at least give an algorithm that would
> make
> > > use of this tag?
> >
> > When you use a different linestyle for rendering single and double track,
> then
> > (for the middle zoom levels) you can use the linestyle for double track
> on
> > any single track that has this extra tag. Aggregation then takes care of
> > itself.
>
> So, do I understand this correctly: On small zoom levels you want to render
> all
> tracks with track=1ofX and all with track=YofX with Y!=1 don't get
> rendered. It
> is the responsibility of the mapper to decide which of several tracks gets
> to
> be number one, because this is the only one rendered (presumably a "middle"
> one, if available). Of course you still have to render all tracks without
> this
> tag, because you don't know how they hang together.
>
> I guess this could work for rendering. There'll probably be some oddities
> where different railways join, but for small enough zoom levels one can't
> see that. Mappers would need some guidance on how to tag railway yards,
> larger stations etc. so that it comes out right.
>
> Jochen
> --
> Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/ +49-721-388298
>
>
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