Radial Placements

A NeoForge 1.21.1 mod that adds the equidistant_ring structure placement type — place structures in configurable circular formations around any center point.

Features

• Place a fixed number of structures evenly spaced in a ring at a configurable radius
• Deterministic placement seeded by world seed — same seed always produces the same ring
• Round-robin mode: assign different structures to specific nodes in the same ring
• Configurable center point, rotation angle, distance variance, and spread tolerance
• Works with datapacks and mod-provided structure sets
• Debug logging shows exact placement coordinates on first world load

Installation

Drop the mod JAR into your mods/ folder. Requires NeoForge for Minecraft 1.21.1.

Placement Type

radial_placements:equidistant_ring

Configuration

Structure sets are defined as JSON files at:

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

Basic Example

Place 6 villages in a ring 500 blocks from world origin:

{
  "structures": [
    { "structure": "minecraft:village_plains", "weight": 1 },
    { "structure": "minecraft:village_desert", "weight": 1 },
    { "structure": "minecraft:village_savanna", "weight": 1 },
    { "structure": "minecraft:village_snowy", "weight": 1 },
    { "structure": "minecraft:village_taiga", "weight": 1 }
  ],
  "placement": {
    "type": "radial_placements:equidistant_ring",
    "label": "villages",
    "salt": 74029831,
    "distance": 500,
    "count": 6
  }
}

Note: Include multiple biome variants of a structure so the ring works across different biomes. A structure silently fails if its target chunk has an incompatible biome.

Placement Fields

Required

Field	Type	Description
type	string	Must be "radial_placements:equidistant_ring"
salt	int	Unique seed salt. Use a different salt per structure set to avoid overlap.
distance	int	Radius in blocks from center to ring nodes.
count	int	Number of evenly-spaced positions around the ring.

Optional

Field	Type	Default	Description
label	string	"unnamed"	Identifier shown in log output for this placement.
spread_tolerance	int	3	Chunk scatter radius around each node. Higher values help structures find valid biomes.
distance_variance	int	50	Max block deviation from distance. Each node randomly shifts closer/farther by up to this amount.
center_x	int	0	Ring center X in block coordinates.
center_z	int	0	Ring center Z in block coordinates.
fixed_angle	float	-1.0	Starting angle in degrees. Negative = randomized per world seed. Set 0.0+ to lock orientation.
total_structures	int	1	Round-robin mode: how many different structure sets share this ring.
structure_index	int	0	Round-robin mode: which slice of nodes this placement handles (0-based).
frequency	float	1.0	Probability (0-1) each node actually attempts generation.
frequency_reduction_method	string	"default"	One of: default, legacy_type_1, legacy_type_2, legacy_type_3.
locate_offset	[x,y,z]	[0,0,0]	Offset for /locate command results.
exclusion_zone	object	none	Prevents spawning near another structure set. Format: {"other_set": "<id>", "chunk_count": <int>}

Round-Robin Mode

To place different structures at different positions in the same ring, create one structure set file per structure type. All files share the same salt, distance, count, and ring parameters, but each gets a unique structure_index.

Example: 3 structures at 120 degrees apart

ring_village.json — Node 0:

{
  "structures": [{ "structure": "minecraft:village_plains", "weight": 1 }],
  "placement": {
    "type": "radial_placements:equidistant_ring",
    "label": "village",
    "salt": 74029831,
    "distance": 300,
    "count": 3,
    "spread_tolerance": 0,
    "distance_variance": 0,
    "total_structures": 3,
    "structure_index": 0
  }
}

ring_outpost.json — Node 1:

{
  "structures": [{ "structure": "minecraft:pillager_outpost", "weight": 1 }],
  "placement": {
    "type": "radial_placements:equidistant_ring",
    "label": "outpost",
    "salt": 74029831,
    "distance": 300,
    "count": 3,
    "spread_tolerance": 0,
    "distance_variance": 0,
    "total_structures": 3,
    "structure_index": 1
  }
}

ring_portal.json — Node 2:

{
  "structures": [{ "structure": "minecraft:ruined_portal", "weight": 1 }],
  "placement": {
    "type": "radial_placements:equidistant_ring",
    "label": "portal",
    "salt": 74029831,
    "distance": 300,
    "count": 3,
    "spread_tolerance": 0,
    "distance_variance": 0,
    "total_structures": 3,
    "structure_index": 2
  }
}

The salt, distance, count, distance_variance, spread_tolerance, center_x, center_z, and fixed_angle must be identical across all files sharing a ring so node positions stay synchronized.

How Round-Robin Node Assignment Works

With count: 6 and total_structures: 3:

Node	Angle	structure_index	Structure
0	0	0	Village
1	60	1	Outpost
2	120	2	Portal
3	180	0	Village
4	240	1	Outpost
5	300	2	Portal

Assignment formula: node_index % total_structures == structure_index

Log Output

On first chunk generation, the mod logs ring node positions at INFO level:

[RadialPlacements] Computing ring 'village': salt=74029831, distance=300, count=3, ...
[RadialPlacements]   'village' Node 0 -> block(-232, ~, 200) chunk(-15, 12) angle=139.6deg dist=300

Use these coordinates to locate or verify structure placement. Additional codec/loading details are logged at DEBUG level.

Tips

• Biome coverage: Include all biome variants of a structure (e.g., all village types, all ruined portal types) so nodes work across biomes.
• Superflat testing: Use minecraft:village_plains or minecraft:pillager_outpost on superflat worlds — the entire world is plains biome.
• Perfect circles: Set distance_variance: 0 and spread_tolerance: 0 for exact geometric placement.
• Reasonable count: Keep count under 128. Each node is evaluated per generated chunk.
• Unique salts: Every structure set needs a unique salt value. Reusing salts causes rings to overlap — except round-robin sets which must share the same salt.
• Structure selection: Within a single structure set file, Minecraft picks randomly from the structures array by weight. Use round-robin mode for deterministic structure-to-node assignment.

Pack Format

For use in datapacks with Minecraft 1.21.1, use pack_format: 48:

{
  "pack": {
    "pack_format": 48,
    "description": "My ring structures"
  }
}

Building

./gradlew build

Output JAR is in build/libs/.

License

GNU GPL 3.0