All landuse needs sort_key (default)

[nvkelso]

In this tile, the grass don't define sort_key:

http://vector.dev.mapzen.com/osm/all/17/38588/49285.topojson?api_key=vector-tiles-HqUVidw

{
type: "Polygon",
properties: {
id: 372703843,
source: "openstreetmap.org",
kind: "grass",
min_zoom: 12.7632,
area: 507
},
arcs: [
[
38
]
]
},

[zerebubuth]

Landuse sort keys are only defined for kinds in this list, which doesn't include grass. What sort_key would you like it to have -- or is there a default that should get applied?

[nvkelso]

It should default to 1 (an int), since earth is 0 and landuse should default sort above that.

[nvkelso]

With Brett's help I've worked around this in the scene file so this doesn't need to git fixed ASAP.

[nvkelso]

I've sketched out proposed sort keys in the attached Open Office document.

sort_key.ods.zip

This is based on what we're doing now in server code and how that is sometimes hacked in the scene file to achieve the cartographic design.

tl;dr

• Moves the current sort_key range from [0,40] to [0,405].
• All feature kinds now have sort_key values, "no" duplicate values (at least for landuse, some for roads)

Design goals:

• Allow for data "underlays" at various places in the z-orders between logical groupings (mostly between layers).
• Allow future growth in each layer's kind values.
• Allow some intermixing of features between layers.
• Live within a z-fighting world, but not go crazy with per tile feature geom area sorts.

@zerebubuth, @rmarianski, @bcamper, @blair1618, @meetar, @sensescape to sanity check

[nvkelso]

Related: #446.