Generate a Map

Use Mimir’s mapgen tool to procedurally generate Dungeondraft-format maps from biome presets or custom YAML configurations.

What Mapgen Creates

Mapgen generates .dungeondraft_map files containing:

Noise-based terrain with blended textures
Trees, grass, and other vegetation
Roads and rivers that follow the terrain
Rooms with walls, doors, and windows
Water bodies, elevation contours, and lighting
Polygon-based layouts for irregular room shapes

Output files open directly in Dungeondraft for further editing or UVTT export.

Quick Start: Using a Preset

Generate a map from one of 12 built-in biome presets:

mimir-mapgen generate --preset forest --output my-forest.dungeondraft_map

Use a specific seed for reproducible results:

mimir-mapgen generate --preset forest --seed 42 --output my-forest.dungeondraft_map

List Available Presets

mimir-mapgen list-presets

Preset	Size	Description
`forest`	32x32	Dense temperate forest with dirt paths, scattered rocks, and natural clearings
`grassland`	32x32	Open rolling hills with sparse trees and wildflowers
`cave`	24x24	Underground cavern with rocky terrain and dark ambient lighting
`desert`	32x32	Arid sandy wasteland with rocky outcrops and sparse scrub
`lake`	32x32	Tranquil woodland pond with grassy shores and scattered trees
`ice_lake`	32x32	Frozen lake with cracked ice, snow-covered shores, and frigid water
`arctic`	32x32	Frozen tundra with snow drifts, exposed rock, and harsh conditions
`island_tropical`	32x32	Tropical island with sandy beaches, palm trees, and warm ocean
`island_forest`	32x32	Forested island in a lake with dirt shores and dense tree cover
`island_arctic`	32x32	Snow-covered island surrounded by frigid dark water
`swamp`	32x32	Dark, murky wetland with stagnant water, dead trees, and dim lighting
`forest_river`	32x32	Dense forest bisected by a meandering river with rocky banks

Some presets have aliases (e.g., tropical_island for island_tropical, pond for lake).

Custom YAML Configs

For full control, write a YAML configuration file:

name: "Forest Clearing"
width: 32
height: 32
seed: 42

terrain:
  slots:
    - texture: "res://textures/terrain/terrain_grass.png"
      lower: 0.0
      upper: 0.5
    - texture: "res://textures/terrain/terrain_dirt.png"
      lower: 0.4
      upper: 0.7
    - texture: "res://textures/terrain/terrain_stone.png"
      lower: 0.6
      upper: 0.9
    - texture: "res://textures/terrain/terrain_gravel.png"
      lower: 0.8
      upper: 1.0

trees:
  - tree:
      textures:
        - "res://textures/objects/more_trees/oak_01.png"
        - "res://textures/objects/more_trees/oak_02.png"
      min_distance: 500.0
      noise_lower: 0.4
      noise_upper: 0.75
      probability: 0.5

roads:
  - {}

Generate from the config:

mimir-mapgen generate config.yaml --output clearing.dungeondraft_map

Validate a Config

Check a config for errors without generating:

mimir-mapgen validate config.yaml

Iterating on Maps

Maps are deterministic — the same seed and config produce the same map. To iterate:

Generate with a specific seed
Open in Dungeondraft and review
Adjust config parameters
Regenerate with the same seed to compare changes
Try different seeds for different terrain layouts

Mapgen is also available as an MCP tool (generate_map) through Mimir’s AI assistant integration. Describe the scene you want — “a misty forest clearing with a road” — and the assistant will build the YAML config and generate the map for you.

Mimir - D&D Campaign Assistant