Gameplay / world

Generated stables

Buildings that generate in the world with horses already in them — horses a player could not have bred yet, from breeds and gene combinations the wild population does not hand out. Three ship; each is somebody else’s build, and the attributions below are the point of this page as much as the mechanics are. Built 2026-09-07, not play-tested — checklist in verification §0-AK.

The three

Who lives in each

Horse Stable — the good, plain horses

Always seven, and the only stable with a field: four outside under the sky, three in the stalls. Every horse is high-rarity and entirely natural — two forced loci of rare tier or better, and no magical gene at all. It is the stable a player is meant to find first: nothing about it is impossible, and everything about it took somebody a long time to breed.

Stables — the Friesian magic line

Two to twelve horses, all in stalls, all Friesian. Every one carries at least one homozygous magical trait, and a ladder of extras: a 10% chance of a second, 5% of a third, halving each time, up to ten extra. So most of them have exactly one, a handful have two, and somewhere out there is a horse with eleven.

TM U Stable — the show yard

Three to fifteen horses, all in stalls, drawn from the white-marking breeds: American Paint, Appaloosa, Knabstrupper, Gypsy Vanner, Clydesdale, Shire, Mustang, Kiger Mustang, Shetland, Icelandic, Marwari, Falabella, American Miniature. No magical gene that paints — a horse here may still glow or heal, but it may not be a colour no real horse could be, because the whole point of the yard is the markings.

What a stable may never do

Adding one: two files and no Java

That is the whole design, and it is why the generation half is vanilla’s and the horses half is this mod’s, joined only by a structure id. A pack that ships only the worldgen gets an empty building; one that ships only the stable file is ignored until a structure by that id exists. Both failures are quiet and neither breaks a world.

1. The building

A Minecraft structure NBT at data/<ns>/structure/<id>.nbt, plus the three ordinary vanilla worldgen files that place it — worldgen/structure/<id>.json, worldgen/structure_set/<id>.json and worldgen/template_pool/<id>.json. Copy this mod’s and change the ids; the structures here are minecraft:jigsaw with a single-element start pool, terrain_adaptation: beard_thin, and a random_spread placement.

2. The horses

One file at data/<ns>/horsegenetics/stable/<id>.json. Everything but structure has a default, so the shortest useful one is two lines.

{
  "structure": "horsegenetics:horse_stable",
  "name": "Horse Stable",
  "min_horses": 7,
  "max_horses": 7,
  "field": 4,
  "breeds": ["friesian"],
  "magic": "none",
  "rare_natural_genes": 2,
  "rare_tier": "rare",
  "min_magic": 1,
  "max_magic": 11,
  "extra_magic_chance": 0.10,
  "extra_magic_falloff": 0.5
}

How it finds the stalls

A stall is not a thing a structure NBT can say, and requiring a modder to bake data markers into somebody else’s schematic would make “drop in an NBT” untrue. So server/StablePopulator reads the placed blocks:

• a standing spot is a solid floor with two blocks of air on it — the shape a horse occupies;
• a stall is a standing spot that is enclosed (at least two of its four sides are a fence, gate, wall, door or solid block) and has something over its head;
• a field spot is a standing spot with open sky over grass, dirt or a path.

Two sides rather than three, deliberately: a stall’s open side is its gate and the one opposite is often open to the aisle, so three would find only boxes, and a box is not a stall. One spot per column, so a horse on a stall floor and another on its roof are not two stalls.

It is a heuristic and it is meant to be. It costs a modder nothing, it degrades to “put them in the field” rather than to “put them in a wall”, and a stable that asks for three stalled horses in a building with two stalls gets two and the third outside. The owner’s phrasing for the first stable was “3 in the stalls (if possible)”, which is exactly this contract.

When the horses arrive

There is no “a structure finished generating” event. What there is: a chunk load, and a StructureStart that knows the piece’s whole bounding box. So a stable is queued when a loading chunk reports a start for it, and populated 40 ticks later — by which time the neighbouring chunks the piece spans have had their own feature stage and the stalls actually exist. It waits again if any of them is still unloaded, because a horse spawned into an unloaded chunk is a horse that never existed.

A stable writes two log lines, and which one is missing says which half broke: [Stables] queued … when it is noticed, and [Stables] filled … with N horse(s) (X stall, Y field found) when it is populated. Neither is gated by debug.announce — they are once per stable per world, and they are what a bug report needs.

A per-level StablePopulationData remembers which stables have been filled, keyed by structure id and bounding-box corner. Without it a stable would gain another seven horses every time a player walked back to it — the classic failure of this whole class of hook, and the kind that looks like a feature for two days and then is a paddock with three hundred horses in it.

The draw is seeded off the world seed, the corner and the structure id, so the same stable in the same world is the same stable however many times its chunk is reloaded, and a bug report naming a location can be reproduced. Every horse is setPersistenceRequired(): one a player walked half a world to find must not despawn because they left to fetch a saddle.

Turning the commentary on

This mod says what it is doing — a cowboy founding, a villager taking the horseman job, a stable being filled — in chat and in the log, because most of it happens where nobody is looking. That is a development tool, so debug.announce in the server config is on in a development run and off in a normal install. It shipped hard-coded on once, and players got [Cowboy] and [Horseman] lines in their chat (gap 137).

Set it to true in a normal install when you are chasing something and want a paste-able log. The line [Debug] chat+log diagnostics enabled=… at startup says which way the switch went, on purpose: a gate you cannot read is how “no debug line ever printed” once became unanswerable.

How often they generate

In chunks, and rarer than a village (32 / 8) by design: each one is a handful of horses a player could not have bred yet, and the smallest, plainest building is the most common of the three. All three share one biome tag, which is open, grassy, buildable ground — a stable on a mountainside is a stable half-buried in a mountainside.

None of these numbers has been played. Spacing and separation are the first thing to turn if stables feel too common or impossible to find, and they are a datapack edit rather than a code change.