game.city — Ashcross

The district: the tile grid every other slice stands on, and the painted city built from it. One tile is one world unit; tile (tx, ty) covers world x in [tx, tx+1) and y in [ty, ty+1), so the surface on top of tile row ty is at world y = ty + 1.

The district is 26 columns wide and runs from y = -8 to y = 103. Columns 0-1 and 24-25 are its own walls, and everything outside that box reads solid, so nothing can walk off the edge of Ashcross and the camera can never look past it.

The climb, bottom to top

Every step of the critical path is within a rise of 2 and a gap of 3 world units, and every one has two tiles of headroom, so the whole climb is walkable with a plain jump. The instruments open shortcuts and side branches; they are never the only way up. That invariant is checked, not assumed — see "Checking it" below.

What it provides

Installed the moment the module is required, before start() runs:

NB.provide.solidAt(x, y)      -- boolean: that world point is inside solid tile
NB.provide.oneWayTopAt(x, y)  -- number?: surface y of a drop-through plank
NB.provide.inMiasmaAt(x, y)   -- boolean: standing miasma

oneWayTopAt answers for the tile the point is in, and also for a point sitting up to 0.05 above a plank's surface, so a doctor standing exactly on a plank still reads as being on it.

Everything else is under NB.ext.city:

Emits "brazier", "pickup", "gate.reached". Calls Camera2D:setBounds(6.5, 19.5, 0.5, 95.5) and NB.claimVisual("city").

How it is drawn

The grid is data; the picture is a separate pass over it. Runs of solid tile are merged greedily into rectangles and each rectangle is one quad wearing art.tiles.tile — a shader written for this slice that repeats a painted sheet across the quad and picks a different cell per tile from a hash of where that tile sits. So a twenty-tile wall is one draw and is never the same cell twenty times. The whole district is a little over two hundred pieces.

The painted sheets live in /zero/source/art/tiles/: masonry, timber, facade (2x2 grids of cells) plus props and gate (cut out of flat magenta by the shader's chroma key). Each surface names a flat palette colour as well, which is what it wears if a sheet is missing — so a gap in the art reads as dim stonework rather than a wall of white cards.

There are no lights in Ashcross. Braziers, tincture caches, lit windows and the lantern over the gate are soft discs of amber laid over the scene by the same shader's radial mode, and the lit lip along the top of every ledge is top_light. That is the entire lighting model of the city.

Everything this slice spawns is temporary and parented under CityFabric, itself under CityRoot. The district is rebuilt from this file on every load and is never written into the scene.

Checking it

local City = require("game.city")
City.build()             -- rebuild the picture; safe to call repeatedly
print(City.dump(8, 26))  -- an ASCII elevation of a slice of the grid

dump renders # solid stone, H house facade, = beam, - plank, x rotten plank, ~ water, , miasma, . air.

Notes for the other slices

• Camera2D:driveTo does not clamp to the bounds this slice sets — the follow path clamps, the override path does not, so a scripted move can take the shot outside the district.
• The route spans are measured off the finished grid, including the headroom test, so a patrol that stays between x0 and x1 never walks into masonry.