[OSM-talk] The segments vs ways vs superways question again...

[80n]

On 1/3/07, Jochen Topf <jochen at remote.org> wrote:
>
> On Wed, Jan 03, 2007 at 01:05:04PM +0100, bvh wrote:
> > On Wed, Jan 03, 2007 at 10:59:36AM -0000, David Earl wrote:
> > > OK, so you could have the area analogy of a group as well; but my
> point was
> > > that it might be a good idea to distinguish areas from paths
> explicitly
> > > rather than implicitly.
> >
> > Why? What problems would it solve?
>
> As it is currently done you can't have areas with holes.


Actually, you can.  The hole should be drawn in an anti-clockwise direction
and its segments should be part of the same way as the outer boundary.

See http://www.w3.org/TR/SVG/painting.html#FillProperties for a description
of how the nonzero rule works.  Alternatively using the evenodd rule should
work and not require the segments to be drawn in any particular direction,
however I've never been able to make this work (it might be me or it might
be a bug in the svg tools that I was using).

For the nonzero approach to be realised in Osmarender, a change is required
to the osmarender rules file (fill-rule='nonzero' needs to be added to the
appropriate css styles).

I don't know whether Mapnik can cope with this, maybe someone can comment on
this.

80n






Jochen
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