Custom dimension/Generator

The format of the  generator compound is dependent on the value of its generator ID, or  type.

When the generator ID type is minecraft:noise:

•  generator: Generation settings used for the dimension.
  •  type (string): The ID of the generator (in this case, minecraft:noise).
  •  seed: The seed used to generate the dimension. In most cases, this is exactly the same as the world seed, but can be different and the dimension generated is based upon this seed and not the world seed.
  •  settings: The shape of the terrain. Can be set to a string to use a preset or a compound with a list of customized options. The string values the settings object can be set to to load default settings include minecraft:overworld for normal Overworld generation, minecraft:amplified for Amplified Overworld generation, minecraft:nether for regular Nether generation, minecraft:caves for Nether-like generation but with Overworld terrain features, minecraft:end to generate the main End island, and minecraft:floating_islands for End floating islands generation.
    •  bedrock_roof_position: The distance from the world height for the top coordinate of the bedrock roof, if out of bounds (0-255) the roof does not appear. e.g. setting this to 32 puts the top of the roof at y=224. If the bedrock roof is low enough, natural terrain still generates above it.
    •  bedrock_floor_position: The y coordinate of the bedrock floor, similar to bedrock_roof_position – setting both floor and roof to 255 generates a single layer of flat bedrock for each of them.
    •  sea_level: The sea level in this dimension between 0 and 255
    •  disable_mob_generation: Can be true or false.
    •  structures: Structure settings
      •  stronghold: Settings for how strongholds should be spawned. The stronghold values under the structures tag appear to be placeholders so that every namespaced structure has a value; these values are the ones that actually control stronghold spawning.
        •  distance: Controls how far apart the strongholds are.
        •  count: How many strongholds to generate.
        •  spread:
      •  structures: List of structures to use in this dimension
        •  <namespaced id>: The key for this field should be the namespaced ID of a structure, a list is available at Java Edition data value § Structures. If structures are not listed, the default structures from the dimension specified in biome_source > type spawn at an extremely increased rate in the biomes they naturally spawn in. All structures must be listed for stable generation of non flat world types.
          •  spacing (number): Average distance between two structure placement attempts of this type in chunks.
          •  separation (number): Minimum distance between two structures of this type in chunks; must be less than spacing.
          •  salt (integer): A number that assists in randomization; see salt (cryptography).
    •  noise: Parameters for world generation.
      •  top_slide: Settings for the curve at the top of the world.
        •  target (integer): The value of the curve. Negative values round off the top of the hills in the affected area, positive values create a roof. Higher values produce larger effects.
        •  size (integer): Defines the size of the affected area from the top of the world. size is calculated using the formula size = <height in blocks> * 0.25 / size_vertical.
        •  offset (integer): Moves the affected area from the top of the world. offset uses the same formula as size so offset = <height in blocks> * 0.25 / size_vertical. For top_slide, positive values move the area down and negative values bring it up.
      •  bottom_slide: Settings for the curve at the bottom of the world.
        •  target (integer): The value of the curve. Negative values remove the floor and round off the bottom of the islands, positive values make a floor. Higher values produce larger effects.
        •  size (integer): Defines the size of the affected area from the bottom of the world. Uses the same formula as in top_slide.
        •  offset (integer): Moves the affected area from the bottom of the world. Uses the same formula as in top_slide. For bottom_slide, positive values move the area up and negative values bring it down.
      •  sampling:
        •  xz_scale (double): Scales the X and Z axis of the noise. Higher values results in more intricate horizontal shapes.
        •  xz_factor (double): Smoothes the noise on the horizontal axis.
        •  y_scale (double): Scales the Y axis of the noise. Higher values result in more intricate vertical shapes.
        •  y_factor (double): Smoothes the noise on the vertical axis.
      •  size_vertical (integer): Changes the Y scale of the landmass. Values between 1 and 15 gradually increase the hill height, above 20 are all above the normal sea level of 63, and higher than 32 give normal land levels of 100+.
      •  size_horizontal (integer): Changes the X/Z scale of the landmass, but not the biomes.
      •  height (integer): Changes the max height of generated terrain by squashing the world. For example, with height=128, the ground is set to Y=32. this does not affect sea level.
      •  density_factor (double):
      •  density_offset (double; values between -1 and 1): Affects the average land level (not sea level).
      •  random_density_offset (boolean; optional):
      •  simplex_surface_noise (boolean):
      •  island_noise_override (boolean; optional): Causes the world to generate like The End with a big island in the center and smaller ones around.
      •  amplified (boolean; optional): Toggles between amplified and normal terrain generation. Can be used alongside large biomes in `vanilla_layered` types, and in any dimension (Nether, End, and custom).
    •  default_block: The block that appears below the top blocks of the world; see Java Edition data values § Blocks
      •  Name: ID of the block
      •  Properties: Block states
        •  state (string): A block state key and its value.
    •  default_fluid: The block used for seas and lakes; see Java Edition data values § Fluids.
      •  Name (string): ID of the block
      •  Properties: Block states
        •  state (string): A block state key and its value.
  •  biome_source: Settings dictating which biomes and biome shapes.
    •  seed (integer): The seed used for biome generation. In most cases, this is exactly the same as the dimension seed (and by extension the world seed), but can be different and the biome generation for this dimension is based upon this seed and not the dimension seed.
    •  type (string): The type of biome generation. Arguments lie in the biome_source compound. Some possible values for type include minecraft:vanilla_layered, minecraft:fixed, minecraft:checkerboard, minecraft:multi_noise, and minecraft:the_end.
      • vanilla_layered: Default and large biome generation used in the overworld.
        •  large_biomes (Boolean): Whether the biomes are large. True for biomes generation in the "Large Biomes" world type.
        •  legacy_biome_init_layer (Boolean): Whether the world was default_1_1.
      • multi_noise: 3D biome generation used in the nether.
        •  preset (string): A preset of the set of biomes to be used, mutually exclusive with  biomes the only valid that's currently supported is minecraft:nether.
        •  biomes: A list of biomes, including their likelihood.
          • : A biome and its properties
            •  biome (string): The biome.
            •  parameters: Properties of the biome.
              •  altitude (float):
              •  weirdness (float):
              •  offset (float):
              •  temperature (float): Affects rain/snow and the color of leaves and grass; see Biome § Biome colors.
              •  humidity (float):
      • the_end: Biome generation used in the end with biome minecraft:the_end in the center and other end biomes around.
      • fixed: a single biome.
        •  biome: The single biome to generate.
      • checkerboard: A biome generation in which biomes are square (or close to square) and repeat along the diagonals.
        •  biomes: A list of biomes that repeat along the diagonals (can be more than 3).
        •  scale: Determines the size of the squares on an exponential scale.

When the generator ID type is minecraft:flat (used for Superflat world generation):

•  generator: Generation settings used for the dimension.
  •  type (string): The ID of the generator (in this case, minecraft:flat).
  •  settings: Superflat settings.
    •  layers: Layer settings.
      • : A superflat layer. This list is interpreted from top to bottom.
        •  height: The number of blocks in the layer.
        •  block: The block the layer is made of.
    •  biome: the single biome of the world
    •  structures: Structure settings
      •  <structure name>: A structure generated with presets before 20w21a. The compound contains the parameters set in the preset. Does not change anything about structure generation, but is set because of the old preset.
      •  structures: List of structures to use in this dimension
        •  <namespaced id>: The key for this field should be the namespaced ID of a structure, a list is available at Java Edition data value § Structures. [note: contrary to that of non-flat worlds, if a structure is not listed, it does not generate at all]
          •  spacing: unsure of purpose. when tested on end cities, anything 10 or lower generated 0 structures. (number)
          •  separation: Spacing between structures, unit? (probably chunks), min, max or average? (number)
          •  salt: A number that assists in randomization; see salt (cryptography).

When the generator ID type is minecraft:debug (used for Debug world generation):

•  generator: Generation settings used for the dimension.
  •  type (string): The ID of the generator (in this case, minecraft:debug).