Biomes

Overview

Biome types: snow_peaks, desert, dry_plains, plains, forest, pine_forest, plus the aquatic biomes sea and lake. They are distributed across the world by Voronoi zones keyed on a moisture value (0→1) and an altitude band, with blend zones between neighbours. Each biome sets surface/subsurface/filler blocks, elevation range, grass colour, NPC cap, vegetation entries and cavern parameters.

Moisture bands are tuned so every biome is actually reachable (the generator's noise clusters around the middle): desert and dry_plains — the only tree-free biomes — take the drier half, plains/forest/pine_forest the wetter half. snow_peaks overrides any biome above altitude 150.

Each biome's elevationMin/elevationMax differ. The surface-height band used for a column is a distance-weighted average of every nearby cell's band (weight falls off over elevationBlendRadius), a continuous field with no sudden primary/secondary switch — so biome borders slope instead of forming cliffs.

Aquatic biomes

sea and lake are flat-band biomes: elevationMin == elevationMax == waterLevel (sea at 60, lake at the pine_forest terrain floor, 72). Extra fields:

• liquid: true — marks the biome as water-filled.
• waterLevel — the flat water surface Y.
• waterMaxDepth (default 8) — deepest the carved basin floor drops below waterLevel.
• waterFloorRelief (default 0) — amplitude in blocks of small-scale noise bumps on the seabed. Damped toward the basin border so the closing ramp to the shore stays clean.
• islandFraction (default 0) — fraction 0..1 of the biome surface that emerges as land. A low-frequency noise field is thresholded (probit-calibrated) so roughly that fraction of the surface rises above waterLevel; a rim band ramps the floor up to each island shore instead of a wall.
• islandHeight (default 8) — peak height in blocks an island crest reaches above waterLevel.
• tintColor — [r, g, b] 0..1, applied as a full-screen colour + tighter fog only while the player's head is underwater (PlayerState.headInLiquid), fading in/out. Out of the water the view is unchanged.

No overflow. Every land biome shares an elevationMin floor L = 72 (≥ the highest waterLevel). The basin floor is carved down by waterMaxDepth × basinEdge, where basinEdge tapers to 0 at any biome border, so the floor rises back to waterLevel exactly at the shore. The water surface stays flat at waterLevel regardless of seabed relief or islands, so a water block is never left exposed next to a lower neighbour — the shore is always solid terrain at or above waterLevel. sea beside lake closes both basins symmetrically at the shared border.

Aquatic biomes carry no vegetation and no caverns, and are excluded from faction spawn placement. Minimap colour comes from their blue grassColor. Their Regions only roster NPCs that live in water (movementMode SWIMMING without WALKING); a SWIMMING-only NPC spawns inside the water column rather than on the surface — see NPCs. Players and land NPCs breathe while submerged: see Liquids → Swimming & breath.

Configuration

data/config/biomes.yaml (optional — falls back to BiomeRegistry.default() if missing; bundled default in resources/config/biomes.yaml):

voronoiCellSize: 256
voronoiBlendRadius: 20     # surface-block dithering width at a border
elevationBlendRadius: 96   # distance falloff for the blended elevation field (anti-cliff)
zoneLevelSafeDist: 768     # cells within this many blocks of origin are zone level 1
zoneLevelMaxDist: 4096     # cells at/beyond this distance are RPG_LEVEL_MAX
biomes:
  - id: snow_peaks
    zones:
      - { moistureMin: 0.0, moistureMax: 1.0, altitudeMin: 150, altitudeMax: 1024 }
    surface: SNOW
    subsurface: STONE
    subsurfaceDepth: 2
    regionBudget: 15
    elevationMin: 150
    elevationMax: 200
    fillers:
      - { type: STONE, density: 0.4 }
      - { type: AIR, density: 0.05 }
    vegetation:
      - { type: pine_tree_snow, density: 0.04 }
    caverns:
      cavernMinHeight: 8
      cavernMaxHeight: 25
      staircaseEnabled: true

Full property list: core/.../world/BiomeDefinition.kt. Schema: biomes.schema.json. Reload with /reload.

Biomes

Defined in data/config/biomes.yaml. Distributed via Voronoi zones (voronoiCellSize: 256, blend 20) keyed on moisture × altitude.

Biome	Surface	Subsurface	Altitude	Moisture	Region budget	Vegetation
snow_peaks	SNOW	STONE	150–1024	0.0–1.0	15	pine_tree_snow @0.04
sea	SAND	SANDSTONE	—–—	0.0–0.06	12
lake	GRAVEL	DIRT	—–—	0.68–0.74	6
desert	SAND	SANDSTONE	—–—	0.06–0.35	10	—
dry_plains	GRASS	SANDSTONE	—–—	0.35–0.46	15	weed @0.08
plains	GRASS	DIRT	—–—	0.46–0.56	20	flower @0.06, weed @0.05, oak_tree @0.01
forest	GRASS	DIRT	—–—	0.56–0.68	25	oak_tree @0.045, flower @0.04, weed @0.04
pine_forest	GRASS	DIRT	—–—	0.74–1.0	20	pine_tree @0.05, weed @0.03

Zone levels

Every Voronoi cell also carries an RPG zone level (VoronoiBiomeZones.zoneLevelAt), used to gate NPC difficulty and player spawn placement. Level scales with the cell seed's distance from the world origin:

• distance ≤ zoneLevelSafeDist (768 blocks) → level 1 — a safe starting basin around (0, 0);
• between zoneLevelSafeDist and zoneLevelMaxDist (4096) → linear ramp;
• distance ≥ zoneLevelMaxDist → RPG_LEVEL_MAX.

So difficulty grows in rough concentric rings outward. New players and faction spawns are placed in a level-below-5, tree-free cell near the origin. This is the spatial counterpart of the skill level → zone tier table.