1.18.2-structures.md

Custom data pack structures in 1.18.2

This guide will showcase how to create a data pack that adds a custom structure to the world. There is also a data pack download of this complete example.

Always leave the world and rejoin to apply the new changes!

⚠️ This guide has moved ⚠️

Updates for both 1.18.2 and 1.19 can be found at https://misode.github.io/guides/adding-custom-structures/

Pack.mcmeta

Like every data pack, we need a pack.mcmeta. In this version, the pack format is 9!

{
  "pack": {
    "pack_format": 9,
    "description": "A tall tower"
  }
}

The structure set

A structure set is where the placement starts. It defines where in the world the structure should be placed, and how rare it is. It takes a weighted list of different structures, allowing structure variants (for example the vanilla nether has a structure set with both the bastion and fortress).

data/example/worldgen/structure_set/tall_towers.json

{
  "structures": [
    {
      "structure": "example:tall_tower",
      "weight": 1
    }
  ],
  "placement": {
    "type": "minecraft:random_spread",
    "spacing": 5,
    "separation": 2,
    "salt": 1646207470
  }
}

Structure sets are made up of two parts:

• structures: A weighted list of configured structure features (see next step).
• placement: The structure placement
  • placement.type: Either random_spread or concentric_rings. The latter is only used by strongholds in vanilla, so we'll focus on random_spread
  • placement.spacing: Roughly the average distance in chunks between two structures in this set.
  • placement.separation: The minimum distance in chunks. Needs to be smaller than spacing.
  • placement.salt: A random number that is combined with the world seed. Always use a different random number for different structures, otherwise they will end up being placed in the same spot!

When using the random_spread placement type, it generates structures grid-based. Here's an illustration of the above example with spacing = 5, separation = 2. There will be one structure attempt in each 5x5 chunk grid, and only at X a structure can spawn.

.............
..XXX..XXX..X
..XXX..XXX..X
..XXX..XXX..X
.............
.............
..XXX..XXX..X
..XXX..XXX..X
..XXX..XXX..X

The configured structure

The configured structure (feature) is the ID you will be able to reference in /locate.

data/example/worldgen/configured_structure_feature/tall_tower.json

{
  "type": "minecraft:village",
  "config": {
    "start_pool": "example:tall_tower",
    "size": 1
  },
  "biomes": "#minecraft:has_structure/mineshaft",
  "adapt_noise": true,
  "spawn_overrides": {}
}

Let's go over all the fields.

• type: This is the structure feature type. When making custom structures, you almost always want to set this to village or bastion_remnant. There is one important difference between the two: using village will spawn the structure on the surface, while bastion_remnant will always spawn the structure at Y=33.
• config.start_pool: This is a reference to the template pool (see next step).
• config.size: This is a number between 1 and 7. This is important if your structure uses jigsaw. In this simple example, we'll leave it at 1.
• biomes: This controls in which biomes this structure is allowed to generate. You can give it any biome tag, a list of biomes, or a single biome. For easy testing we'll set it to every biome with mineshafts.
• adapt_noise: When true, it will add extra terrain below each structure piece.
• spawn_overrides: This field allows you to override mob spawning inside the structure bounding boxes. This is currently outside the scope of this guide, but you could look at the vanilla monument structure feature as a reference.

The template pool

The template pool defines how to build up your structure. Since we're not using jigsaw, this is quite straight forward: we want to place a single NBT structure.

data/example/worldgen/template_pool/tall_tower.json

{
  "name": "example:tall_tower",
  "fallback": "minecraft:empty",
  "elements": [
    {
      "weight": 1,
      "element": {
        "element_type": "minecraft:single_pool_element",
        "location": "example:stone_tall_tower",
        "projection": "rigid",
        "processors": "minecraft:empty"
      }
    }
  ]
}

Again, let's go over the fields:

• name: For some reason, the game needs the name of this template pool. Just set this to the ID of the template pool.
• fallback: Used in jigsaw structures, but we can simply use minecraft:empty.
• elements: A weighted list of pool elements to choose from. You can add multiple elements here if your structure has different starting structure files. For example in vanilla a plains village has different town center variants.
  • element_type: The type of this element. One of empty_pool_element (placing nothing), feature_pool_element (placing a placed feature), legacy_single_pool_element, list_pool_element, and single_pool_element (placing a structure).
  • location: The path to the structure NBT file. (see next step).
  • projection: Either rigid or terrain_matching. Use the latter if you want the structure to match the terrain, just like village paths do.
  • processors: If you want to run any processor lists, this is quite complicated so again we'll skip this for now and set it to minecraft:empty.

The structure

Creating the structure NBT file is entirely up to you. In this example I'm going to use a tower structure from Gamemode 4.

data/example/structures/stone_tall_tower.nbt

(binary NBT file) Download the structure from this example

Result

stone_tall_tower.nbt

tall-towers-1.18.2.zip

tall-towers-1.19.zip

Thanks but I only zipped it at all so I could upload it. I did the testing without ever tipping it and it still failed to validate

PS: Also validating isn't the same as showing up in the datapack selection