A natural spawn category file represents a spawn category for Natural Generation, denoted by the .rcnc suffix. Each category has a separate chance to spawn a structure within any given chunk.

To view an included Natural Spawn Category, use /#write natural_generation_category <category> ACTIVE (which will write it to the active folder).

File Structure Edit

Using rcnc files (e.g. adventure.rcnc), which are structured as JSONs, you can add your own spawn categories. There is currently no GUI to accomplish this.

Example rcnc file:

  "defaultSpawnChance": 0.0666,
  "generationInfos": [{
     "spawnChance": 0.2,
     "biomeMatcher": "$HOT",
     "dimensionMatcher": "0"
  }, {
     "spawnChance": 0.0,
     "biomeMatcher": "$COLD",
     "dimensionMatcher": "0"
  "structureMinCap": 20,
  "spawnDistanceMultiplier": 0,
  "spawnDistanceMultiplierCap": 1,
  "selectableInGUI": true,
  "title": "Frequent",
  "tooltip": ["Small structures or scenery", "Random structure each 10 chunks"]

The spawnChance parameter in this are the chance to spawn in the specifically matched entry, or respectively defaultSpawnChance for any unmatched one. The generationInfos are a list of entries to match. For example, if set to 0.1, this means there will be one random structure each 10 chunks.

You can also instead provide spawnChances arrays (e.g. "defaultSpawnChances": [0.1, 0.2] and "spawnChances": [0.2, 0.12, 0.3]). This will cause the category to try to spawn in the biome more than once. A spawn chance of 1 and 1 for example would mean that there would always be 2 structures per chunk.

The structureMinCap determines how many structures are needed in the category for it to fulfill its spawn potential. If none is provided, the default of 20 is used. For example, if it is set to 20, and only one structure is registered in the category, it will spawn 1/20th as often as it would if 20 structures were registered. This is meant to prevent the same few structures spawning all over the place if few structures are registered.

The spawnDistanceMultiplier is used to make structures in this category spawn more often when further away from spawn. 0 means no change, -0.5 means half the chance is subtracted each chunk, and 0.5 means half the chance is added each chunk, for example.

To hide the category from users in the GUI, set selectableInGUI to false. Title and tooltip are for the GUI display only.