My experience has been that Mapnik's drawing looks a bit like this:
for each layer in layers:
for each style in layer:
for each geometry in layer data source:
for each rule in style:
for each symbolizer in rule:
draw the geometry using the
symbolizer.
So your first example runs through the geometry set twice, first
drawing the less important roads and then drawing the more important
roads on top. Your second example runs through the geometry set once,
drawing less important roads and more important roads as they come out
of the data source. If your datasource supports it, you can use an
ORDER BY clause to choose which roads to draw first and which to draw
second.
Incidentally these kinds of nuances are something that I'm almost
totally glossing over in Cascadenik, I just don't know how to express
them, though I have gotten requests for something like CSS z-index.
-mike.
On May 6, 2009, at 9:51 PM, arno974 wrote:
>
> Hi all,
>
> I defined differents style for my roads data. This style are used to
> classify the importance of the roads. So I made my style like this :
>
> <Style name="secondaryRoads">
> <Rule>
> <Filter>[roads] = 'Less-important'</Filter>
> ...
> </Rule>
> </Style>
>
> <Style name="primaryRoads-text">
> <Rule>
> <Filter>[roads] = 'More-important'</Filter>
> ...
> </Rule>
> </Style>
>
> With this style everythings works fine.
>
> But if i trie to do it like below, my roads 'less-important' is
> always above
> the 'important roads so I wonder how Mapnik draw the tiles inside a
> style?
>
> <Style name="secondaryRoads">
> <Rule>
> <Filter>[roads] = 'Less-important'</Filter>
> ...
> </Rule>
> <Rule>
> <Filter>[roads] = 'More-important'</Filter>
> ...
> </Rule>
> </Style>
>
> Thanks for your answer.
>
> Best regards
>
>
> --
> View this message in context:
> http://www.nabble.com/In-which-order-Mapnik-draw-the-tiles-inside-a-style-tp23420181p23420181.html
> Sent from the Mapnik - Users mailing list archive at Nabble.com.
>
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michal migurski- [email protected]
415.558.1610
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