JSON_GUIDE.md

WorldGen Editor JSON Guide

The mod now works through a datapack-style world preset. For a new world, choose this world type:

WGE: Islands

Inside this preset, Minecraft still uses the normal minecraft:noise generator, but with two modded worldgen resources:

• worldgen_editor:island_biome_source selects ocean and land biomes before chunk generation.
• worldgen_editor:island_final_density softly reshapes vanilla density so oceans form around configured islands.

This is much more stable than replacing generator internals after the vanilla generator has already been created.

Config Location

Main config file:

config/worldgen_editor/worldgen_editor.json

It selects a preset:

{
  "enabled": true,
  "active_preset": "default"
}

Preset files live here:

config/worldgen_editor/presets/default.json
config/worldgen_editor/presets/archipelago.json
config/worldgen_editor/presets/small_island.json

Bundled presets and matching world types:

• WGE: Islands / default: the current standard island set.
• WGE: Archipelago / archipelago: several islands and an archipelago cluster.
• WGE: Small Island / small_island: one small spawn island.

If the files do not exist, the mod creates defaults. New installs use worldgen_editor.json and presets/*.json; continents.json is only a legacy fallback for old configs where the new main config is not present.

Preset priority is:

world type preset > config active_preset > legacy continents.json

For example, a world created with WGE: Archipelago uses config/worldgen_editor/presets/archipelago.json even if worldgen_editor.json says "active_preset": "default". This keeps the Minecraft world type and the generated world stable. The config-selected preset is used when no WGE world type preset is stored.

The selected preset is read:

• once when the mod initializes, so a default file can be created early;
• again when a world/server starts, before the island mask is rebuilt for that world's seed;
• again when /worldgen_editor reload is used.

This means you can edit worldgen_editor.json or a preset JSON from the main menu and then create a new world without restarting the game.

After editing the config while a world is already running, use:

/worldgen_editor reload

reload only affects newly generated chunks. Minecraft does not rebuild already generated chunks, biomes, structures, or blocks.

Enabling

The main config has a top-level flag:

{
  "enabled": true,
  "active_preset": "default"
}

• enabled: false means the island mask is not applied, even when the island world preset is selected.
• enabled: true allows island generation in worlds where the per-world flag is also enabled.
• active_preset chooses a fallback file from config/worldgen_editor/presets/ when the world itself does not already store a WGE preset.

Each preset file has the usual island fields:

{
  "outer_ocean": "minecraft:deep_ocean",
  "entries": []
}

• outer_ocean is optional. It controls the biome used outside every island/archipelago mask. If omitted, the mod uses minecraft:deep_ocean. If the configured biome is missing or not ocean-like, the mod logs a warning and falls back to minecraft:deep_ocean.

For each world, the mod stores an extra file:

<world_folder>/worldgen_editor/worldgen_editor.json

New world-state files are created as:

{
  "enabled": true
}

Final logic:

generation enabled = config/worldgen_editor/worldgen_editor.json enabled && <world>/worldgen_editor/worldgen_editor.json enabled

Commands:

/worldgen_editor enable
/worldgen_editor disable
/worldgen_editor status
/worldgen_editor preset <name>
/worldgen_editor reload

You can choose a preset in the world type screen when creating a world, or change the config fallback with:

/worldgen_editor preset small_island

Smallest Valid Island

At minimum, an island needs a center and a radius:

{
  "enabled": true,
  "outer_ocean": "minecraft:deep_ocean",
  "entries": [
    {
      "x": 0,
      "z": 0,
      "radius": 850
    }
  ]
}

This creates one roughly round island around coordinates 0, 0.

Recommended Example

{
  "enabled": true,
  "entries": [
    {
      "type": "island",
      "name": "Spawn Island",
      "x": 0,
      "z": 0,
      "radius": 950,
      "shape_power": 2.2,
      "roughness": 0.16,
      "shore_width": 0.18,
      "temperature": "temperate",
      "biome_patch_size": 768,
      "noise": {
        "seed": "spawn"
      }
    },
    {
      "type": "ocean",
      "name": "Central Strait",
      "x": 360,
      "z": 80,
      "radius_x": 230,
      "radius_z": 980,
      "rotation": 24,
      "shape_power": 1.35,
      "roughness": 0.18,
      "shore_width": 0.22,
      "temperature": "standard",
      "biome_patch_size": 1024,
      "noise": {
        "seed": "central_strait"
      }
    },
    {
      "type": "archipelago",
      "name": "Western Archipelago",
      "x": -1700,
      "z": 720,
      "radius": 1100,
      "count": 16,
      "min_radius": 90,
      "max_radius": 250,
      "spread": 0.88,
      "spacing": 1.15,
      "min_stretch": 0.7,
      "max_stretch": 1.65,
      "min_shape_power": 1.2,
      "max_shape_power": 3.7,
      "roughness": 0.22,
      "shore_width": 0.17,
      "temperature": "warm",
      "biome_patch_size": 1024,
      "noise": {
        "seed": "western_archipelago"
      }
    },
    {
      "type": "island",
      "name": "Long Island",
      "x": 1350,
      "z": -650,
      "radius": 520,
      "stretch_x": 1.7,
      "stretch_z": 0.75,
      "rotation": 25,
      "roughness": 0.14,
      "noise": {
        "seed": "long_island"
      }
    }
  ]
}

Island Fields

• type is optional. Supported values are island, ocean, and archipelago. If omitted, the entry is a normal island.
• name is an optional display name.
• x is the island center on the X axis.
• z is the island center on the Z axis.
• radius is the base island size.
• radius_x and radius_z define separate radii for more precise stretched shapes.
• stretch_x and stretch_z multiply the base radius.
• rotation rotates the island in degrees.
• shape_power changes the base shape before coastline noise is applied. 2.0 is the old circle/ellipse behavior, lower values are sharper and more diamond-like, higher values are broader and more rounded-square.
• roughness controls coastline noise strength from 0.0 to 1.0.
• shore_width controls the soft transition width between land and ocean.
• overlap controls whether this island can add its mask on top of other islands.
• temperature controls climate-biome selection for this entry. Supported values are standard, cold, temperate, and warm. The aliases auto, vanilla, standart, and the old field name climate also work.
• biome_patch_size controls how large fallback-biome patches are, in blocks. Default is 512. Smaller values create visible biome mosaic patches; larger values make islands and archipelagos more consistent.
• exclude_biomes prevents specific vanilla/modded biomes from being selected for this entry. Use biome ids like minecraft:desert or tags like #minecraft:is_badlands.

Most of the time, you only need type, x, z, radius, stretch_x, stretch_z, rotation, shape_power, and roughness.

Entry Types

type: "island"

This is the normal land-producing entry. Old entries without type still use this behavior.

{
  "type": "island",
  "name": "Shaped Island",
  "x": 0,
  "z": 0,
  "radius": 850,
  "stretch_x": 1.4,
  "stretch_z": 0.8,
  "rotation": 18,
  "shape_power": 2.6,
  "roughness": 0.18
}

type: "ocean"

Ocean entries carve water out of land entries. They are useful for straits, bays, inner seas, and unusual coast cuts. Order does not matter: ocean masks are applied after all land masks.

{
  "type": "ocean",
  "name": "Cut Strait",
  "x": 240,
  "z": 0,
  "radius_x": 180,
  "radius_z": 900,
  "rotation": 30,
  "shape_power": 1.3,
  "roughness": 0.2,
  "shore_width": 0.22
}

type: "archipelago"

Archipelago entries do not create one giant island. Instead, they deterministically place many smaller child islands inside the configured cluster radius.

{
  "type": "archipelago",
  "name": "Outer Islands",
  "x": -1800,
  "z": 700,
  "radius": 1100,
  "count": 18,
  "min_radius": 90,
  "max_radius": 260,
  "spread": 0.9,
  "spacing": 1.2,
  "min_stretch": 0.65,
  "max_stretch": 1.6,
  "min_shape_power": 1.2,
  "max_shape_power": 3.8,
  "roughness": 0.22,
  "shore_width": 0.17,
  "noise": {
    "seed": "outer_islands"
  }
}

• count is the target number of child islands.
• min_radius and max_radius control child island sizes.
• spread controls how much of the cluster radius can be used.
• spacing controls how strongly child islands try to avoid each other.
• min_stretch and max_stretch randomize child island elongation.
• min_shape_power and max_shape_power randomize child island base shapes.
• If the requested count cannot fit with the chosen spacing, the mod logs a warning and uses the islands it could place.
• Child island placement, size, stretch, rotation, shape, and coastline noise depend only on this entry's noise.seed. Changing the Minecraft world seed no longer moves the individual archipelago islands.

Biome Exclusions

Biome selection is automatic. The mod keeps vanilla land biomes when they are allowed, picks climate-aware ocean variants for ocean zones, and uses safe fallback land biomes when a chosen biome is excluded.

You can override the automatic climate per entry with temperature:

{
  "type": "archipelago",
  "name": "Warm Islands",
  "x": -1200,
  "z": 400,
  "radius": 900,
  "temperature": "warm"
}

Supported values:

• standard follows Minecraft's own delegate biome choice as much as possible. This is the default when temperature is omitted and it does not filter climates.
• cold allows only cold land/ocean fallbacks, such as snowy plains, taiga, frozen ocean, and cold ocean variants.
• temperate allows moderate land/ocean fallbacks, such as plains, forests, meadow, normal ocean, and deep ocean. It avoids desert, savanna, jungle, snowy, and frozen fallbacks.
• warm allows warm land fallbacks, such as savanna, jungle, and desert. For oceans it allows warm/lukewarm/normal non-cold ocean variants and blocks cold/frozen/deep-cold oceans.

temperature affects only biome selection performed by WorldGen Editor. With standard, vanilla/modded delegate biomes are preserved unless excluded. With warm, cold, or temperate, an incompatible delegate biome is replaced with a matching fallback. Unknown modded biomes are kept under standard; under manual temperatures they are replaced unless their tags clearly match the requested climate.

Compatibility aliases:

• auto = standard
• vanilla = standard
• standart = standard
• climate can be used as an old field name instead of temperature

Use biome_patch_size to control how patchy replacement biomes are:

{
  "type": "archipelago",
  "name": "Large Biome Zones",
  "x": -1800,
  "z": 700,
  "radius": 1100,
  "biome_patch_size": 1024
}

Tuning:

• 32 to 128 creates small, visible biome patches.
• 256 to 512 is a balanced range.
• 1024 to 2048 makes archipelagos feel more unified.
• Valid range is 4 to 4096.

This is useful for archipelagos: small patches can look varied, but large patches are usually better when you want one island chain to feel like a single climate region.

Use exclude_biomes on any entry:

{
  "type": "island",
  "name": "No Deserts",
  "x": 0,
  "z": 0,
  "radius": 850,
  "exclude_biomes": [
    "minecraft:desert",
    "minecraft:savanna",
    "#minecraft:is_badlands"
  ]
}

Notes:

• Exact ids exclude one biome.
• Tags exclude every biome in that tag.
• Archipelago children inherit exclusions from their parent archipelago entry.
• If every preferred fallback is excluded, the mod logs a warning and uses a safe vanilla fallback.

Coast Noise

{
  "x": 0,
  "z": 0,
  "radius": 700,
  "roughness": 0.22,
  "noise": {
    "seed": "coast_1",
    "scale": 3.5,
    "first_octave": -1,
    "amplitudes": [1.0, 0.78, 0.55, 0.34]
  }
}

• noise.seed changes the coastline shape without changing island center or size.
• noise.scale increases noise frequency.
• noise.first_octave controls the starting octave, which mostly means the size of the largest coastline waves.
• noise.amplitudes controls how much each octave contributes to the final coastline shape.

noise.first_octave

You can usually leave this at -1.

The mod builds coastline noise from several layers, also called octaves. Each next octave is twice as detailed as the previous one. first_octave decides where that stack starts:

• -2 starts with larger, slower coastline bends.
• -1 is the default and works well for most islands.
• 0 starts with smaller, faster coastline variation.
• 1 and higher can make the edge busy and noisy, especially on small islands.

Practical tuning:

"first_octave": -2

Use this when a large island should have broad bays and capes instead of small jagged edges.

"first_octave": -1

Use this as the normal default.

"first_octave": 0

Use this only when you want more small-scale coastline wobble.

noise.amplitudes

amplitudes is a list of octave strengths. The first number affects the first octave, the second number affects the next octave, and so on.

Default:

"amplitudes": [1.0, 0.78, 0.55, 0.34]

This means:

• 1.0: strongest large coastline shape.
• 0.78: medium details still matter.
• 0.55: smaller details are visible.
• 0.34: fine details are present, but weaker.

Smoother, simpler coast:

"amplitudes": [1.0, 0.45, 0.18]

More detailed coast:

"amplitudes": [1.0, 0.85, 0.65, 0.45, 0.25]

Very smooth, almost ellipse-like coast:

"amplitudes": [1.0]

Rules of thumb:

• Keep the first value near 1.0.
• Let later values get smaller.
• Avoid many strong values like [1.0, 1.0, 1.0, 1.0] unless you intentionally want a chaotic coast.
• If coastlines look noisy, reduce later amplitudes first.
• If coastlines look too round, increase roughness before making amplitudes extreme.

Smoother coastline:

"roughness": 0.08

Rougher coastline:

"roughness": 0.25

Old Format Compatibility

The mod still understands older field names:

• center_x = x
• center_z = z
• x_divisor = radius_x
• z_divisor = radius_z
• rotation_degrees = rotation
• multiplier = size_multiplier

The new format is shorter, but older datapack-style files should continue to work.

Important Limits

• Select the WGE: Islands, WGE: Archipelago, or WGE: Small Island world preset when creating an island world.
• Changing the config after world creation does not rebuild old chunks.
• For a completely clean result, create a new world or deliberately delete old region files.
• Islands use vanilla land biomes inside the island mask. The mod does not manually draw rivers or swamps.
• Ocean around islands is produced through noise settings and biome source, not by late block replacement.

Common Issues

• The island did not appear: check that the world preset is one of the WGE: ... presets and that /worldgen_editor status reports the expected world_preset.
• The world looks vanilla: check enabled in config/worldgen_editor/worldgen_editor.json and /worldgen_editor status.
• JSON changed but the nearby terrain did not: you are looking at already generated chunks.
• Reload failed: check commas, quotes, and required fields x, z, and radius.
• Shores are too sharp: lower roughness or increase shore_width.
• The island is too low or too small: increase radius; very small islands are more affected by vanilla lowland or river terrain.