[Tilesathome] RFC: New Osmarender features

[Jiri Klement]

> If it was also possible to put layer overrides, like for captions,
> inside rules far down the hierarchy I think we could make the
> stylesheets _much_ easier to understand.

Actually it's is possible. I've changed orp and XSLT recently so that
now layer attribute is set on instruction, not <rule>. But all refs
and captions checks for osmarender:noRenderRef/Name so it's not that
easy.

>> The trouble here is you may find out you need some instruction to
>> render bellow highway casing. This can solved either by renumbering
>> all highway's relativeLayers or by using relativeLayer like 100, 200
>> so you have enough space to insert another layer. Both principles are
>> too error prone.
>
> Why not simply go for this? It should allow most things, yet still be
> easy enough to understand that you don't have to write too much
> documentation ;)

I forgot to mention it in the proposal, but I was going to support
setting layer/relativeLayer directly on the instruction as well. It is
indeed easier for simple stylesheets, but I still think that for big
stylesheets is better to use SetLayer.

> KISS is imho a very, very good principle.

I love complicated things :-)

I've rewritten the relativeLayer part. relativeLayer is now z-index.
Instead of layer=-5 you say z-mode=bottom and instead of layer=5 you
say z-mode=top. Dodi noted on the Talk page that relativeLayer and
SetLayer where a bit confusing, this will be hopefully clearer.

--
Jiri