Template pool
A template pool is a structured collection of structure pieces used by Minecraft’s jigsaw structure system to procedurally generate complex structures in the world, such as villages, bastions, and custom modded structures.
Each structure piece within a template pool represents a structure template, which is a predefined NBT structure file containing blocks and entities to place.
During world generation, the jigsaw system randomly selects structure pieces from the pool, using weighted probabilities defined within the pool’s JSON configuration. This allows for variability and replayability, ensuring structures feel organic and diverse each time they generate.
Template pools are defined and configured using JSON files located within a data pack under:
- data/<namespace>/worldgen/template_pool
Extended adds it's own jigsaw piece type in addition to Minecraft's Jigsaw Pieces. This page documents the format of Extended's lotrextended:extended_single_pool_element type and how it integrates and differs from vanilla's minecraft:single_pool_element.
Pool JSON format
The root tag
fallback: (required)
- A fallback template pool<namespace>/worldgen/template_pool/<path>
- Used in the case structures in this pool can't generate.
elements: A list of elements to randomly select from.An element.
weight:
int(required)
- How likely this element is to be chosen when using this pool. Value between 1 and 150 (inclusive).
element_type:namespace:type(required)
- The type of the pool element. See below.
projection:rigidorterrain_matching(required)
- Defines the terrain projection type. Can berigidto place a fixed structure (like a house), orterrain_matchingto match the terrain height (like a village road).
Additional fields are available depending on the spicific element_type defined.
Element JSON formats
Vanilla Single Element
A pool element represents a single piece of a jigsaw structure.
The element
element_type:
minecraft:single_pool_element(required)
- Identifies this as an extended single pool element.
projection: See above (required)
location:example:flower_forest/village_house(required)
- The location of the structure file for this entry. Located indata/<namespace>/structure/<path>
processors:namespace:path_to_a_processor_list(required)
- The processor list applied before placement. See Processor List.
- Can be left asminecraft:empty
Extended Single Pool Element
A pool element represents a single piece of a jigsaw structure but with additional fields to facilitate the needs of extended's structures.
The element
element_type:
lotrextended:extended_single_pool_element(required)
- Identifies this as an extended single pool element.
projection: See above (required)
location:example:flower_forest/village_house(required)
- The location of the structure file for this entry. Located indata/<namespace>/structure/<path>
processors:namespace:path_to_a_processor_list(required)
- The processor list applied before placement. See Processor List.
- Can be left asminecraft:empty
apply_waterlogging:true(default)
- Iftrue, liquids in the structure will propergate through waterloggable blocks. Iffalse, liquids are not allowed to spread.
max_place_distance:80(default)
- Maximum distance the structure can attempt to place blocks from its origin.
max_depth:7(default)
- The maximum recursive generation depth when structures call children.
ignore_bb_checks:false(default)
- Iftrue, bypasses bounding box intersection checks, allowing overlapping structures. When enabled, generates a minimal bounding box at the point of connection (used for things such as lampposts).
blacklist_name:"NOTSET"(default)
- A custom identifier used for some pieces skip using the certian piece if another piece with the same blacklistable name was already spawned (used to have only one smithy in a village for example).
snap_to_water_height:false(default)
- Iftrue, will attempt to align the structure's Y position to the water surface height (y=62) when generating.