Predefined City and Sphere Reference¶

TL;DR

A predefined city or sphere pins that feature to an exact dimension and chunk coordinate instead of letting generation choose. The mod ships no examples of either type, and both work. game test

The sphere keys are absent in 6.0.3

centerx, centerz, chunkx, chunkz, dimension and radius exist in 5.3.29 and again from 6.1.6 onward, but not in 6.0.3. See Key availability. code review

On four versions this asset type does nothing at all

5.3.29, 6.0.3, 6.1.6 and 6.2.3 load a predefined city, validate it and register it, and then never read the registry. Every pinned building and street is absent and nothing is logged. A deliberately invalid value in the file still stops the server from booting, so the file being accepted proves nothing about it being used. Place buildings through a city style selector on those versions instead. game test code review

The folder names carry no underscore, and the city folder is spelled differently on different versions:

data/<namespace>/lostcities/predefinedcities/<name>.json     7.4.12 and later, except 8.2.2
data/<namespace>/lostcities/predefinedcites/<name>.json      5.3.29, 6.1.6, 6.2.2, 6.2.3, 8.2.2
data/<namespace>/lostcities/predefinedcitites/<name>.json    6.0.3
data/<namespace>/lostcities/predefinedspheres/<name>.json    everywhere the type exists

A folder that does not match the spelling the version compiled in is never scanned, and the pack looks empty rather than wrong. game test code review

Predefined City¶

Key code review	Required	Meaning
`dimension`	yes	The dimension ID this applies to
`chunkx` / `chunkz`	yes	The centre chunk coordinate
`radius`	yes	The radius, in chunks
`citystyle`	yes	The city style to use here
`buildings`	no	A list of pinned buildings. See the table below
`streets`	no	A list of pinned streets, each `{chunkx, chunkz}`

A pinned building¶

Key code review	Required	Default	Meaning
`building`	yes		The building name to place
`chunkx` / `chunkz`	yes		An offset from the city centre, in chunks, not a world chunk coordinate. `0, 0` is the centre chunk itself and `2, -1` is two chunks east and one north of it game test
`multi`	no	`false`	`true` treats the name as a Multi-Building rather than a single building
`preventruins`	no	`false`	`true` makes the ruin pass skip this building, so a landmark stays intact game test

Both coordinate pairs are named chunkx and chunkz and they do not mean the same thing

On the city itself they are absolute world chunk coordinates. On a pinned building or street they are relative to that city. The mod adds the two together, so a city at chunkx: 8 holding a building at chunkx: 2 places that building at world chunk 10, which is block 160. game test

Writing a world coordinate on a pinned building therefore lands it that many chunks past where you meant, and a result outside radius never appears. Nothing is logged either way. game test

A pinned street¶

Key code review	Required	Meaning
`chunkx` / `chunkz`	yes	An offset from the city centre, exactly as above. That chunk becomes a street instead of rolling `buildingchance`

What a predefined city overrides¶

Pinning a city is not a hint. The chunk you name becomes a city centre outright. game test

Normally decided by	Inside a predefined city
`cityChance`	Ignored. The centre chunk is a city centre even at `cityChance: 0.0`, which is the cleanest way to get exactly one city in a world game test
The city radius roll	Fixed to `radius` code review
The World Style's weighted city style pick	Fixed to `citystyle` code review
`buildingchance`, per chunk	Ignored on any chunk holding a pinned building or a pinned street game test

At cityChance: 0.0, an unpinned chunk inside the radius is not a city chunk

The radius bounds the city, and on its own it does not make the chunks inside it part of one. With cityChance at 0.0 and nothing else pinned, the chunk beside a pinned building reported is city: false and generated as open ground, so the building had no street next to it and no front was ever drawn. game test

Pin the streets you want, as the streets list above does, and those chunks become city. This is worth ruling out first when a feature that needs a street neighbour appears to do nothing. game test

Predefined Sphere¶

Key code review	Required	Meaning
`dimension`	yes	The dimension ID
`chunkx` / `chunkz`	yes	The chunk coordinate
`centerx` / `centerz`	yes	The sphere centre, in blocks
`radius`	yes	The sphere radius

Every key on a predefined sphere is required, and there are no optional ones. code review

A sphere pinned at centerx: 136, centerz: 136 with radius: 40 built its dome exactly there: 513 glass blocks in the centre chunk, where the shell only crosses above and below, 1093 in the chunk just inside the western edge where it stands almost vertical, and none in the chunk beginning at 136 + 40. game test

The whole dome is one block, not a mix

A sphere's glass character is resolved once per sphere, so a weighted list of four glass types produces a dome of one of them rather than a speckled one. CitySphere keeps a single glassBlock and the fill uses it throughout. game test code review

Example¶

A landmark city centred on world chunk 8, 8

{
  "dimension": "lostcities:lostcity",
  "chunkx": 8,
  "chunkz": 8,
  "radius": 8,
  "citystyle": "citystyle_standard",
  "buildings": [
    { "building": "town_hall", "chunkx": 0, "chunkz": 0, "preventruins": true },
    { "building": "office", "chunkx": 2, "chunkz": 0 }
  ],
  "streets": [
    { "chunkx": 1, "chunkz": 0 }
  ]
}

The city covers world chunks 0 to 16 on both axes. town_hall lands on chunk 8, 8, that is block 128, 128. office lands on chunk 10, 8, that is block 160, 128. The street sits between them on chunk 9, 8. game test

Pin to the dimension the profile is actually driving

Choosing a profile with the Cities button makes the overworld the Lost Cities world, while dimensionsWithProfiles wires lostcities:lostcity. A city pinned to the wrong one of those appears not to generate at all, with nothing logged. The shipped example packs pin to both. game test

onlyPredefined turns off random spheres

A profile's cityspheres.onlyPredefined makes the mod generate predefined spheres and nothing else, for a fixed hand-placed set rather than a random scatter. See Profile. code review