[OSM-talk] A table of cross-renderer tag support

[Steve Bennett]

On Fri, Dec 11, 2009 at 11:33 PM, Dave F. <davefox at madasafish.com> wrote:
> This 'supports' needs clarifying.
>
> For example you list bridge=aqueduct as yes, yet it doesn't render.
> So what is the difference in meaning between support & render?

The term "recognises" is probably better than "supports". I guess the
definition is something like "is at least dimly aware of".

Looking at that specific case, the code that triggered its inclusion
in the table is this:

<Layer name="waterway-bridges" status="on" srs="&osm2pgsql_projection;">
    <StyleName>waterway-bridges</StyleName>
    <Datasource>
      <Parameter name="table">(select way,name from &prefix;_line
where waterway='canal' and bridge in ('yes','true','1','aqueduct')
order by z_order) as water</Parameter>
      &datasource-settings;
    </Datasource>
</Layer>

and this:
<Layer name="water_lines" status="on" srs="&osm2pgsql_projection;">
    <StyleName>water_lines</StyleName>
    <Datasource>
      <Parameter name="table">
      (select way,waterway,disused,name,
      case when tunnel in ('yes','true','1') then 'yes'::text else
tunnel end as tunnel
      from &prefix;_line
      where waterway in
('weir','river','canal','derelict_canal','stream','drain')
        and (bridge is null or bridge not in ('yes','true','1','aqueduct'))
      order by z_order
      ) as water_lines</Parameter>
      &datasource-settings;
    </Datasource>
</Layer>

So I guess while it may not have particular graphics associated with
it, bridge=aqueduct ways will get rendered at a higher z-order than
other sources of water, for instance. I'm sure a Mapnik expert can
fill us in on all the implications.

Steve