gravitystorm/openstreetmap-carto — pull request #173 by math1985 (2013-09-17 20:17:22+00:00)
Title: Change layer order

The layer order used to be as follows.

(bridges) B
direction-pre-bridges.directions R
access-pre-bridges.access R
waterway-bridges R/B
roads-low-zoom R/B
aerialways R/B
ferry-routes T/R
turning-circle-fill R
roads-fill R
tracks-notunnel-nobridge R
buildings ???
buildings-lz ???
highway-area-fill R
roads-casing R
highway-area-casing R
area-barriers.barriers T/R
cliffs T/R
line-barriers.barriers T/R
tracks-tunnels T
footbikecycle-tunnels T
turning-circle-casing R
landuse-overlay T/R
castlewalls-poly.castlewalls T/R
castlewalls.castlewalls T/R
citywalls T/R
tunnels T

I classified all layers between and including the bridge-layers and the tunnels-layer with one of the following classifications:

B Bridge level.
R/B Above roads but below bridges.
R Road level.
T/R Above tunnels but below roads.
T Tunnel level.

I grouped all of the layers within one class together, without changing the order within the classes. For now, I ignored the buildings-layers, due to the difficulties with ordering buildings, highways and highway-areas described in #172.

This change causes a couple of changes in the rendering, which mainly occur in rare cases.
- Casings of turning circles are now drawn above foot/bike/track tunnels (they were already drawn above other tunnels), and above cliffs and barriers (just like other roads are drawn above cliffs and barriers).
- Landuse-overlays (i.e., military and national park), castlewalls, and citywalls are now drawn above foot/bike/track tunnels (they were already drawn above other tunnels).
- Ferry-routes are now drawn below roads (highways, tracks, turning-circles, and highway-areas).
- Railways on level 12 (due to the #roads-low-zoom layer), aerialways, and waterway-bridges are now drawn above access and directions markers of roads (they were already drawn above the roads themselves).