Custom world generation

Custom world generation allows data packs to change how the world generates. This is particularly useful in conjunction with custom worlds.

Biome categories
Biome categories are used by several game mechanics:


 * Any biomes in the category  will be considered part of the ocean temperature category; other temperature categories are controlled by the biome's temperature value. This means that biomes in the   category should typically be placed near each other.
 * Biomes in the categories  and   will play the underwater music instead of their normal music when the player is underwater.
 * Zombie sieges and patrols will not spawn in biomes in the category.
 * Rabbits spawning in biomes in the category  will always have the desert skin, unless they are in a biome with   set to.
 * Mobs in the  category spawn much less often in biomes in the category.
 * Ocean monuments will not spawn in any biome which isn't in the category  or.

Carvers
Carvers are used to add carved out regions of biomes, either replaced with air or liquid.

Surface builders
Surface builders control how the surface of the terrain is shaped and what blocks it is generated with.

Features
Features are unique elements of the world like trees, flowers, ore, etc.

JSON format
When another configured feature is required inside the settings, it can either be provided with a string tag as the namespaced id of another configured feature, or with a compound tag as a nested definition.

Data types
The JSON format makes use of these relatively complex data types many times, so to avoid filling the main JSON format tree with too much redundant information, they are provided here:

Feature names
These are all of the valid names which can be used for configured features:



Decorators
Decorators are used to modify the generation of features in various ways.

Decorator names
These are all of the valid names which can be used for configured decorators:



Structure features
Structure features are a special type of feature that generates a structure. The logic behind what qualifies as a structure feature versus a regular feature is unclear. Dungeons and Desert wells are typically considered structures, but are not structure features. Also, Nether Fossils are structure features while Fossils are not even though they are essentially the same feature.

Structure feature names
These are all of the valid names which can be used for structure features:



Jigsaw pools
Jigsaw pools or template pools are used to generate structures using jigsaw blocks