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mcf-worldgen

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UpdatedMay 16, 2026 at 15:29

Create and modify Minecraft Java Edition world generation definitions. Use when working with custom dimensions, biomes, configured/placed features, structures, template pools, noise settings, density functions, carvers, or world presets. Covers all worldgen JSON formats for version 26.1.2.

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Minecraft Custom World Generation

File Location

World generation files are under: data/<namespace>/worldgen/

worldgen/
├── biome/                          # Biome definitions
├── configured_carver/              # Cave/canyon carvers
├── configured_feature/             # Configured features
├── density_function/               # Density functions
├── flat_level_generator_preset/    # Superflat presets
├── multi_noise_biome_source_parameter_list/ # Biome distribution
├── noise/                          # Noise definitions
├── noise_settings/                 # Noise settings (terrain shape)
├── placed_feature/                 # Placed features
├── processor_list/                 # Structure processors
├── structure/                      # Structure definitions
├── structure_set/                  # Structure sets (placement)
├── template_pool/                  # Jigsaw template pools
└── world_preset/                   # World presets

Note: Worldgen definitions are NOT hot-reloadable - must re-enter world.

Dimension Definition

data/<namespace>/dimension/<name>.json

{
  "type": "minecraft:overworld",
  "generator": {
    "type": "minecraft:noise",
    "settings": "minecraft:overworld",
    "biome_source": {
      "type": "minecraft:multi_noise",
      "preset": "minecraft:overworld"
    }
  }
}

Generator types: minecraft:noise, minecraft:flat, minecraft:debug

Dimension Type

data/<namespace>/dimension_type/<name>.json

{
  "ultrawarm": false,
  "natural": true,
  "coordinate_scale": 1.0,
  "has_skylight": true,
  "has_ceiling": false,
  "ambient_light": 0.0,
  "monster_spawn_light_level": { "type": "minecraft:uniform", "min_inclusive": 0, "max_inclusive": 7 },
  "monster_spawn_block_light_limit": 0,
  "piglin_safe": false,
  "bed_works": true,
  "respawn_anchor_works": false,
  "has_raids": true,
  "logical_height": 384,
  "min_y": -64,
  "height": 384,
  "infiniburn": "#minecraft:infiniburn_overworld",
  "effects": "minecraft:overworld",
  "cloud_height": 192  # New in v26.1
}

Biome Definition

data/<namespace>/worldgen/biome/<name>.json

{
  "temperature": 0.8,
  "downfall": 0.4,
  "has_precipitation": true,
  "temperature_modifier": "none",
  "effects": {
    "sky_color": 7972607,
    "water_fog_color": 329011,
    "fog_color": 12638463,
    "water_color": 4159204,
    "foliage_color": 5877296,
    "grass_color": 8431444,
    "grass_color_modifier": "none",
    "music": {
      "sound": "minecraft:music.overworld.desert",
      "min_delay": 12000,
      "max_delay": 24000,
      "replace_current_music": false
    },
    "ambient_sound": "minecraft:ambient.cave",
    "additions_sound": {
      "sound": "minecraft:ambient.cave",
      "tick_chance": 0.001
    },
    "mood_sound": {
      "sound": "minecraft:ambient.cave",
      "tick_delay": 6000,
      "block_search_extent": 8,
      "offset": 2.0
    },
    "particle": {
      "options": { "type": "minecraft:ash" },
      "probability": 0.05
    }
  },
  "carvers": [
    "minecraft:cave",
    "minecraft:cave_extra_underground",
    "minecraft:canyon"
  ],
  "features": [
    ["minecraft:lake_lava_underground"],
    ["minecraft:forest_rock"],
    [],
    [],
    [],
    [],
    ["minecraft:ore_dirt"],
    ["minecraft:ore_gravel"],
    ["minecraft:ore_coal_upper"],
    ["minecraft:ore_iron_upper"],
    ["minecraft:ore_gold"]
  ],
  "creature_spawn_probability": 0.1,
  "spawners": {
    "monster": [
      {
        "type": "minecraft:zombie",
        "weight": 100,
        "minCount": 4,
        "maxCount": 4
      }
    ],
    "creature": [...],
    "ambient": [...],
    "underground_water_creature": [...],
    "water_creature": [...],
    "water_ambient": [...],
    "misc": [...]
  }
}

Features Array Index

Each index represents a generation step:

0: Raw generation
1: Lakes
2: Local modifications
3: Underground structures
4: Surface structures
5: Strongholds
6: Underground ores
7: Underground ores (less common)
8: Underground ores (rare)
9: Vegetal decoration
10: Top layer modification

Configured Feature

data/<namespace>/worldgen/configured_feature/<name>.json

{
  "type": "minecraft:ore",
  "config": {
    "targets": [
      {
        "target": {
          "predicate_type": "minecraft:tag_match",
          "tag": "minecraft:stone_ore_replaceables"
        },
        "state": { "Name": "minecraft:iron_ore" }
      }
    ],
    "size": 9,
    "discard_chance_on_air_exposure": 0.5
  }
}

Common feature types: ore, tree, flower, block_pile, lake, spring, random_patch, simple_block, vegetation_patch, glow_lichen, sculk_patch, netherrack_replace_blobs, basalt_pillar, delta_feature, geode, fossil, root_system, bamboo, huge_fungus, twisting_vines, weeping_vines, coral, sea_pickle, kelp, seagrass, dripstone_cluster, pointed_dripstone, large_dripstone, underwater_magma, multiface_growth, forest_rock, ice_spike, iceberg, blue_ice, end_island, end_spike, end_gateway, chorus_plant

Placed Feature

data/<namespace>/worldgen/placed_feature/<name>.json

{
  "feature": "minecraft:ore_iron",
  "placement": [
    {
      "type": "minecraft:count",
      "count": 20
    },
    {
      "type": "minecraft:in_square"
    },
    {
      "type": "minecraft:height_range",
      "height": {
        "type": "minecraft:trapezoid",
        "min_inclusive": { "absolute": -24 },
        "max_inclusive": { "absolute": 56 }
      }
    },
    {
      "type": "minecraft:biome"
    }
  ]
}

Placement types: count, in_square, height_range, heightmap, biome, block_predicate_filter, surface_water_depth_filter, surface_relative_threshold_filter, rarity_filter, random_offset, noise_based_count, noise_threshold_count, count_on_every_layer, environment_scan, random_spread, cave_surface, rigid_body

Structure Definition

data/<namespace>/worldgen/structure/<name>.json

Types: minecraft:jigsaw, minecraft:structure_template, minecraft:buried_treasure, minecraft:ruined_portal, minecraft:ocean_ruin, minecraft:shipwreck, minecraft:end_city, minecraft:woodland_mansion, minecraft:fortress, minecraft:swamp_hut, minecraft:igloo, minecraft:desert_pyramid, minecraft:jungle_temple

Jigsaw Structure

{
  "type": "minecraft:jigsaw",
  "biomes": "#minecraft:has_structure/village_plains",
  "step": "surface_structures",
  "spawn_overrides": {},
  "terrain_adaptation": "beard_thin",
  "start_pool": "minecraft:village/plains/town_centers",
  "size": 6,
  "start_height": {
    "absolute": 0
  },
  "project_start_to_heightmap": "WORLD_SURFACE_WG",
  "max_distance_from_center": 80,
  "use_expansion_hack": true
}

Template Pool (Jigsaw)

data/<namespace>/worldgen/template_pool/<name>.json

{
  "fallback": "minecraft:village/plains/terminators",
  "elements": [
    {
      "weight": 1,
      "element": {
        "element_type": "minecraft:legacy_single_pool_element",
        "location": "minecraft:village/plains/houses/plains_small_house_1",
        "processors": "minecraft:mossify_10_percent",
        "projection": "rigid"
      }
    }
  ]
}

Element types: minecraft:single_pool_element, minecraft:list_pool_element, minecraft:legacy_single_pool_element, minecraft:empty_pool_element Projections: rigid, terrain_matching, terrain_adaptive

Processor List

data/<namespace>/worldgen/processor_list/<name>.json

{
  "processors": [
    {
      "processor_type": "minecraft:rule",
      "rules": [
        {
          "input_predicate": {
            "predicate_type": "minecraft:random_block_match",
            "block": "minecraft:cobblestone",
            "probability": 0.1
          },
          "location_predicate": { "predicate_type": "minecraft:always_true" },
          "output_state": { "Name": "minecraft:mossy_cobblestone" }
        }
      ]
    }
  ]
}

Processor types: minecraft:rule, minecraft:block_rot, minecraft:block_age, minecraft:protected_blocks, minecraft:capped, minecraft:blackstone_replace

Structure Set

data/<namespace>/worldgen/structure_set/<name>.json

{
  "structures": [
    {
      "structure": "minecraft:village_plains",
      "weight": 1
    }
  ],
  "placement": {
    "type": "minecraft:random_spread",
    "salt": 10387312,
    "spacing": 34,
    "separation": 8,
    "spread_type": "triangular"
  }
}

Placement types: minecraft:random_spread, minecraft:concentric_rings

Noise Settings

data/<namespace>/worldgen/noise_settings/<name>.json

Controls terrain shape:

{
  "sea_level": 63,
  "disable_mob_generation": false,
  "aquifers_enabled": true,
  "ore_veins_enabled": true,
  "legacy_random_source": false,
  "default_block": { "Name": "minecraft:stone" },
  "default_fluid": { "Name": "minecraft:water", "Properties": { "level": "0" } },
  "noise": {
    "min_y": -64,
    "height": 384,
    "size_horizontal": 1,
    "size_vertical": 2
  },
  "noise_router": {
    "barrier": 0,
    "fluid_level_floodedness": "minecraft:overworld/floodedness",
    "fluid_level_spread": 0,
    "lava": "minecraft:overworld/lava",
    "temperature": "minecraft:overworld/temperature",
    "vegetation": "minecraft:overworld/vegetation",
    "continents": "minecraft:overworld/continents",
    "erosion": "minecraft:overworld/erosion",
    "depth": "minecraft:overworld/depth",
    "ridges": "minecraft:overworld/ridges",
    "initial_density_without_jaggedness": "minecraft:overworld/base_3d_noise",
    "final_density": "minecraft:overworld/base_3d_noise",
    "vein_toggle": 0,
    "vein_ridged": 0,
    "vein_gap": 0
  },
  "spawn_target": [],
  "surface_rule": {
    "type": "minecraft:sequence",
    "sequence": [
      {
        "type": "minecraft:condition",
        "if_true": {
          "type": "minecraft:stone_depth",
          "offset": 0,
          "surface_type": "ceiling",
          "add_surface_depth": false,
          "secondary_depth_range": 0
        },
        "then_run": {
          "type": "minecraft:block",
          "result_state": { "Name": "minecraft:stone" }
        }
      }
    ]
  }
}

Density Function

data/<namespace>/worldgen/density_function/<name>.json

{
  "type": "minecraft:add",
  "argument1": "minecraft:overworld/base_3d_noise",
  "argument2": 0.05
}

Types: add, multiply, min, max, abs, square, cube, half_negative, quarter_negative, squeeze, noise, shifted_noise, range_choice, constant, flat_cache, cache_2d, cache_once, interpolated, blend_alpha, blend_offset, beardifier, old_blend_noise, y_clamped_gradient, surface_depth, weird_scaled_sampler, shift_a, shift_b, shift, slide, spline

World Preset

data/<namespace>/worldgen/world_preset/<name>.json

{
  "dimensions": {
    "minecraft:overworld": {
      "type": "minecraft:overworld",
      "generator": {
        "type": "minecraft:noise",
        "settings": "minecraft:overworld",
        "biome_source": {
          "type": "minecraft:multi_noise",
          "preset": "minecraft:overworld"
        }
      }
    },
    "minecraft:the_nether": {
      "type": "minecraft:the_nether",
      "generator": {
        "type": "minecraft:noise",
        "settings": "minecraft:nether",
        "biome_source": {
          "type": "minecraft:multi_noise",
          "preset": "minecraft:nether"
        }
      }
    },
    "minecraft:the_end": {
      "type": "minecraft:the_end",
      "generator": {
        "type": "minecraft:noise",
        "settings": "minecraft:end",
        "biome_source": {
          "type": "minecraft:the_end"
        }
      }
    }
  }
}

Multi-Noise Biome Source Parameter List

data/<namespace>/worldgen/multi_noise_biome_source_parameter_list/<name>.json

{
  "preset": "minecraft:overworld",
  "biomes": [
    {
      "biome": "minecraft:plains",
      "parameters": {
        "temperature": [-0.45, 0.55],
        "humidity": [-0.35, 0.35],
        "continentalness": [-0.19, 0.5],
        "erosion": [-1.0, 1.0],
        "weirdness": [-1.0, -0.3],
        "depth": 0,
        "offset": 0
      }
    }
  ]
}

Noise

data/<namespace>/worldgen/noise/<name>.json

{
  "firstOctave": -7,
  "amplitudes": [1.0, 1.0]
}

Carver

data/<namespace>/worldgen/configured_carver/<name>.json

{
  "type": "minecraft:cave",
  "config": {
    "probability": 0.14285715,
    "y": {
      "type": "minecraft:uniform",
      "min_inclusive": { "absolute": 8 },
      "max_inclusive": { "absolute": 180 }
    },
    "yScale": { "type": "minecraft:uniform", "min_inclusive": 0.0, "max_exclusive": 0.5 },
    "lava_level": { "above_bottom": 10 },
    "horizontal_radius_multiplier": { "type": "minecraft:uniform", "min_inclusive": 1.0, "max_exclusive": 1.0 },
    "vertical_radius_multiplier": { "type": "minecraft:uniform", "min_inclusive": 1.0, "max_exclusive": 1.0 },
    "floor_level": { "type": "minecraft:uniform", "min_inclusive": -1.0, "max_exclusive": -0.4 }
  }
}

Carver types: minecraft:cave, minecraft:canyon, minecraft:nether_cave

Block Predicates (Used in Features & Processors)

{ "predicate_type": "minecraft:tag_match", "tag": "minecraft:stone_ore_replaceables" }
{ "predicate_type": "minecraft:block_match", "block": "minecraft:stone" }
{ "predicate_type": "minecraft:random_block_match", "block": "minecraft:stone", "probability": 0.5 }
{ "predicate_type": "minecraft:always_true" }
{ "predicate_type": "minecraft:has_sturdy_face", "offset": [0, -1, 0] }
{ "predicate_type": "minecraft:matching_blocks", "blocks": ["minecraft:stone"], "offset": [0, -1, 0] }
{ "predicate_type": "minecraft:solid", "offset": [0, -1, 0] }
{ "predicate_type": "minecraft:inside_world_bounds", "offset": [0, 0, 0] }
{ "predicate_type": "minecraft:unobstructed", "offset": [0, 0, 0] }

Number Providers (Worldgen)

// Constant
{ "type": "minecraft:constant", "value": 5 }
{ "type": "minecraft:constant", "value": { "type": "minecraft:uniform", "min_inclusive": 1, "max_inclusive": 3 } }

// Uniform
{ "type": "minecraft:uniform", "value": { "min_inclusive": 1, "max_inclusive": 10 } }

// Biased to bottom
{ "type": "minecraft:biased_to_bottom", "value": { "min_inclusive": 1, "max_inclusive": 10 } }

// Clamped
{ "type": "minecraft:clamped", "value": { "min_inclusive": 0, "max_inclusive": 10, "source": { "type": "minecraft:uniform", "min_inclusive": -5, "max_inclusive": 20 } } }

// Clamped normal
{ "type": "minecraft:clamped_normal", "value": { "min": 0, "max": 10, "mean": 5, "deviation": 2 } }

// Weighted list
{ "type": "minecraft:weighted_list", "distribution": [{ "data": 1, "weight": 5 }, { "data": 3, "weight": 2 }] }

Height Providers

{ "type": "minecraft:constant", "value": { "absolute": 64 } }
{ "type": "minecraft:uniform", "min_inclusive": { "absolute": 0 }, "max_inclusive": { "absolute": 256 } }
{ "type": "minecraft:biased_to_bottom", "min_inclusive": { "absolute": 0 }, "max_inclusive": { "absolute": 256 } }
{ "type": "minecraft:very_biased_to_bottom", "min_inclusive": { "absolute": 0 }, "max_inclusive": { "absolute": 256 } }
{ "type": "minecraft:trapezoid", "min_inclusive": { "absolute": 0 }, "max_inclusive": { "absolute": 256 }, "plateau": 0 }

Vertical anchors:

{ "absolute": 64 }
{ "above_bottom": 10 }
{ "below_top": 10 }

Block State Providers

{ "type": "minecraft:simple_state_provider", "state": { "Name": "minecraft:stone" } }
{ "type": "minecraft:weighted_state_provider", "entries": [...] }
{ "type": "minecraft:noise_provider", "noise": { "firstOctave": -7, "amplitudes": [1.0] }, "states": [...], "scale": 0.02 }
{ "type": "minecraft:noise_threshold_provider", "noise": {...}, "states": [...], "threshold": 0.0, "high_chance": 0.5, "scale": 0.02 }
{ "type": "minecraft:dual_noise_provider", "noise": {...}, "variety": 6, "states": [...], "slow_noise": {...}, "slow_scale": 0.005 }
{ "type": "minecraft:randomized_int_state_provider", "source": {...}, "property": "age", "values": { "type": "minecraft:uniform", "min_inclusive": 0, "max_inclusive": 3 } }
{ "type": "minecraft:rule_based_state_provider", "rules": [...] }  # New in v26.1

name	mcf-worldgen
description	Create and modify Minecraft Java Edition world generation definitions. Use when working with custom dimensions, biomes, configured/placed features, structures, template pools, noise settings, density functions, carvers, or world presets. Covers all worldgen JSON formats for version 26.1.2.
license	MIT
compatibility	opencode
metadata	{"version":"1.0","game-version":"26.1.2","category":"minecraft-datapack"}

name	mcf-worldgen
description	Create and modify Minecraft Java Edition world generation definitions. Use when working with custom dimensions, biomes, configured/placed features, structures, template pools, noise settings, density functions, carvers, or world presets. Covers all worldgen JSON formats for version 26.1.2.
license	MIT
compatibility	opencode
metadata	{"version":"1.0","game-version":"26.1.2","category":"minecraft-datapack"}

mcf-worldgen

More from this repository

More from this repository

Minecraft Custom World Generation

File Location

Dimension Definition

Dimension Type

Biome Definition

Features Array Index

Configured Feature

Placed Feature

Structure Definition

Jigsaw Structure

Template Pool (Jigsaw)

Processor List

Structure Set

Noise Settings

Density Function

World Preset

Multi-Noise Biome Source Parameter List

Noise

Carver

Block Predicates (Used in Features & Processors)

Number Providers (Worldgen)

Height Providers

Block State Providers

Minecraft Custom World Generation

File Location

Dimension Definition

Dimension Type

Biome Definition

Features Array Index

Configured Feature

Placed Feature

Structure Definition

Jigsaw Structure

Template Pool (Jigsaw)

Processor List

Structure Set

Noise Settings

Density Function

World Preset

Multi-Noise Biome Source Parameter List

Noise

Carver

Block Predicates (Used in Features & Processors)

Number Providers (Worldgen)

Height Providers

Block State Providers