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Terrain Generation Pipeline

Technical reference for the procedural terrain system.

Pipeline Stages

The terrain worker (terrain.worker.ts) executes these stages sequentially:

1. Elevation Field

Module: TerrainGenerator.generateElevationField()

Multi-octave fractal simplex noise with three additive layers:

Layer Frequency Purpose
Base fBm scale × 2^octave Detail terrain
Continent bias continentScale Large landmasses
Ocean carving oceanScale Deep ocean basins

Post-processing: power redistribution (e^redistributionPower) compresses lowlands.

Optional island mode multiplies by a radial falloff from map centre.

2. Water Distance

Module: TerrainGenerator.computeDistanceToWater()

Multi-pass BFS from all water tiles. Used by both temperature (continentality) and humidity (coastal influence) to avoid computing it twice.

3. Temperature Field

Module: TerrainGenerator.generateTemperatureField()

temp = latitudeGradient × latitudeStrength
     + noiseField × (1 - latitudeStrength)
     - elevationCooling × elevation
     + continentalStrength × waterDistance

4. Humidity Field

Module: TerrainGenerator.generateHumidityField()

humidity = noiseField × (1 - coastalInfluence)
         + coastalProximity × coastalInfluence
         - elevationDrying × elevation

5. Rivers

Module: RiverGenerator in rivers.ts

Minecraft-style noise zero-crossing: rivers appear where |noise(x,y)| < threshold. Two independent layers:

Layer Scale Threshold Width
Primary 0.0009 0.032 4px
Secondary 0.004 0.02 2px

Rivers fade above mountainCutoff elevation and taper near shores. Domain warping (warpStrength: 40) adds organic curves.

Post-process: humidity boost within humidityRadius tiles of rivers.

6. Biome Classification

Module: buildBiomeMap() in biomes.ts

26 biome types classified by elevation/temperature/humidity thresholds:

Water:  deep_ocean, ocean, shore
Cold:   polar_desert, glacier, tundra, alpine
Cool:   boreal_forest, taiga, cold_steppe
Temp:   temperate_desert, steppe, grassland, woodland,
        temperate_forest, scrubland, swamp
Hot:    desert, badlands, savanna, tropical_forest,
        rainforest, wetland, mangrove
High:   highland, mountain

A low-frequency jitter noise field offsets temp/humidity inputs before lookup, breaking up sharp biome boundaries.

7. Resources

Module: generateResources() in resources.ts

Each land tile receives a ResourceType (0–7) and resourceDensity (0–255):

Resource Source
Timber Forest, boreal_forest, taiga, woodland, rainforest
Stone Highland, mountain, alpine, badlands
Iron Mountain/highland/badlands + ore noise > 0.72
Gold Mountain + river-adjacent + ore noise > 0.88
Fertile Soil Grassland, savanna, wetland (humidity-weighted)
Fish Shore-adjacent land tiles
Fur & Game Taiga, boreal_forest (cold forests)

Priority: Gold > Iron > Fish > biome-default.

8. Strategic Points

Module: detectStrategicPoints() in strategic.ts

Auto-detects geographically significant locations:

Type Detection Method Score
River Crossing Low-elevation land adjacent to river, walkable in 4 dirs 0–10
Mountain Pass Saddle points (local elevation minimum between peaks) 0–10
Strait Narrow water gap between two landmasses 0–10
Peninsula High water-to-total ratio in scan circle 0–10

9. ImageData Rendering

Each field is rendered to an ImageData (RGBA pixel buffer):

  • Elevation: blue → green → brown → white gradient
  • Temperature: blue → red gradient
  • Humidity: tan → teal gradient
  • Biome: 26-colour palette with river overlay
  • Strategic: biome base + highlighted points
  • Resource: biome base + tinted resource deposits
  • Political: nation territory colours + borders

All buffers are posted back as transferable ArrayBuffers (zero-copy).

Configuration

All parameters live in Config.ts → defaultConfig.terrain:

terrain: {
  seed,                    // World seed (number)
  map: { width, height, tileSize, chunkSize, seaLevel, islandMode },
  elevation: { scale, octaves, persistence, lacunarity, ... },
  temperature: { scale, octaves, latitudeStrength, elevationCooling, ... },
  humidity: { scale, octaves, coastalInfluence, elevationDrying },
  rivers: { primaryScale, secondaryScale, thresholds, widths, ... },
  strategic: { radii, thresholds },
  biomeNoise: { scale, octaves, jitter amounts },
  biomes: { elevation thresholds, jitter amounts },
  resources: { oreScale, goldRarity, ironRarity, minDensity },
  nations: { count, minSpacing }
}