On 20/08/2008 10:24, Dermot McNally wrote: > Layers exist to > determine the drawing order of overlapping elements, nothing more.
... which rather violates the "don't tag for the renderer" maxim, yes? There's a few cases where it can't be avoided, like where a bridge goes over another bridge in a complex intersection or by chance, as here: http://www.openstreetmap.org/?lat=52.329752&lon=-0.192132&zoom=18&layers=B00FTF But for the vast majority of cases, we ought to be able to tell without using layers. For example, - a waterway always goes under a road (except when marked as an aqueduct) irrespective of whether a bridge is marked or not. - a bridge always goes over anything intersecting with it (other than possibly another bridge). - a pond should always render on top of a park (indeed any area enclosed in another area could generally be assumed to render on top: even special cases like underground reservoirs still need to be rendered on top even if they are beneath a surrounding landuse area, say). - linear ways (should) always render on top of areas, irrespective of any layering, POIs above those and all text on top. David _______________________________________________ josm-dev mailing list josm-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/josm-dev