Biomes

A biome describes a region of the world: its climate, its colors and sounds, which mobs spawn there, which carvers dig through it and which features decorate it. It does not decide where it appears - that is the job of the biome source of a dimension.

val myBiome = dp.biome("my_biome") {
	temperature = 0.8f
	downfall = 0.4f
	hasPrecipitation = true

	attributes {
		skyColor(0x78A7FF)
		fogColor(0xC0D8FF)
	}

	effects {
		waterColor = color(0x3F76E4)
	}
}

References: Biome, Biome definition, misode's biome generator

Where Biomes Land In The World

The vanilla Overworld places biomes in a 6-dimensional climate space. Each biome claims an interval on every axis, and the game picks the closest match for a position. These are the same six parameters a multiNoise biome source lists per entry:

The vanilla Overworld uses the built-in overworld multi-noise preset, so these bands are fixed in the game and not in a datapack file (bounds above are rounded to four decimals). In its table of standard middle-terrain biomes, snowy_plains sits at temperature -1.0..-0.45 with humidity -1.0..0.1, dark_forest at temperature -0.15..0.2 with humidity 0.3..1.0, and desert at temperature 0.55..1.0 with every humidity.

The temperature and downfall fields on the biome itself are a different thing: they drive in-world behavior such as snow instead of rain, water freezing, and cauldrons filling.

Climate Fields

Colors And Atmosphere

Two blocks share this job, and the split matters:

• attributes { } covers everything the camera sees or hears - sky, fog, particles, music, ambient sounds - plus gameplay rules. It is the same system dimension types use, so a biome value simply overrides the dimension value. See Environment Attributes.
• effects { } covers the biome-local block and liquid tints, which are not attributes.

attributes {
	skyColor(0x78A7FF)
	fogColor(0xC0D8FF, EnvironmentAttributeModifier.ADD)
}

effects {
	waterColor = color(0x3F76E4)       // Defaults to the vanilla overworld blue.
	foliageColor = color(0x59AE30)
	dryFoliageColor = color(0xA0A04C)
	grassColor = color(0x79C05A)
	grassColorModifier = GrassColorModifier.SWAMP
}

Colors serialize as decimal integers. grassColorModifier applies the vanilla SWAMP or DARK_FOREST post-processing on top of the computed grass color.

Reference: Biome definition - Effects

Mob Spawns

Mob spawns are the natural_mob_spawns environment attribute, set in the attributes { } block of the biome (or of a dimension type), as is the creatureWorldGenSpawnProbability of the initial creature spawn during world generation.

spawnsByCategory declares what may spawn per mob category. Within a category, weight is a relative probability against the other entries, and count is the size of a spawned group, written by minCount/maxCount or set to any int provider.

attributes {
	creatureWorldGenSpawnProbability(0.07f)
	naturalMobSpawns {
		spawnsByCategory {
			creature {
				spawner(EntityTypes.COW, weight = 6, minCount = 2, maxCount = 4)
				spawner(EntityTypes.SHEEP, weight = 8, minCount = 2, maxCount = 4)
			}
			monster {
				spawner(EntityTypes.SKELETON, weight = 80, minCount = 1, maxCount = 2)
				spawner(EntityTypes.ZOMBIE, weight = 80, minCount = 1, maxCount = 2)
			}
		}
	}
}

Categories: ambient, axolotls, creature, misc, monster, undergroundWaterCreature, waterAmbient, waterCreature.

spawnCosts caps density with an energy budget instead of a raw count. Each mob spends charge from a shared energyBudget, so a crowded area stops spawning before it becomes a mob farm.

naturalMobSpawns {
	spawnCosts {
		spawnCost(EntityTypes.COW, energyBudget = 1.2f, charge = 0.1f)
	}
}

References: Mob spawning, Spawn costs

Carvers

carvers is a flat list of carver IDs, or a single carver tag. They run during the carvers step, after the terrain noise and before any feature.

carvers(myCaveCarver, Carvers.CAVE)

See Carvers.

Features

features lists placed features per decoration step. Every property is a plain list, and leaving one empty simply means nothing of yours generates at that step.

features {
	fluidSprings = listOf(PlacedFeatures.SPRING_WATER)
	lakes = listOf(PlacedFeatures.LAKE_LAVA_UNDERGROUND)
	localModifications = listOf(PlacedFeatures.AMETHYST_GEODE)
	surfaceStructures = listOf(PlacedFeatures.DESERT_WELL)
	topLayerModification = listOf(PlacedFeatures.FREEZE_TOP_LAYER)
	undergroundDecoration = listOf(PlacedFeatures.GLOW_LICHEN)
	undergroundOres = listOf(orePlaced)
	undergroundStructures = listOf(PlacedFeatures.MONSTER_ROOM)
	vegetalDecoration = listOf(treePlaced, flowerPlaced)
}

See Features.

Complete Example

fun DataPack.highlandsBiome(treePlaced: PlacedFeatureArgument, orePlaced: PlacedFeatureArgument) {
	val cave = carversBuilder.cave("highlands_cave") {
		probability = 0.08
		y = uniformHeightProvider(absolute(32), absolute(128))
		floorLevel(-0.2f)
	}

	biome("highlands") {
		temperature = 0.8f
		downfall = 0.3f
		hasPrecipitation = true

		attributes {
			fogColor(0xBFEFFF)
			skyColor(0x99D9FF)
			waterFogColor(0x0A2C4F)
			naturalMobSpawns {
				spawnsByCategory {
					creature {
						spawner(EntityTypes.COW, 6, 2, 4)
						spawner(EntityTypes.SHEEP, 8, 2, 4)
					}
					monster {
						spawner(EntityTypes.SKELETON, 80, 1, 2)
					}
				}
				spawnCosts {
					spawnCost(EntityTypes.COW, 1.2f, 0.1f)
				}
			}
		}

		effects {
			waterColor = color(0x34A7F0)
		}

		carvers(cave)

		features {
			undergroundOres = listOf(orePlaced)
			vegetalDecoration = listOf(treePlaced)
		}
	}
}

See Also

• Carvers - the caves and canyons a biome runs
• Dimensions - biome sources placing biomes in a world
• Environment Attributes - the full attribute reference
• Features - the placed features a biome lists
• World Generation - overview of the worldgen system