jame581 Procedural Generation in Godot 4.3+
All examples target Godot 4.3+ with no deprecated APIs. GDScript is shown first, then C#.
Related skills: 2d-essentials for TileMapLayer usage, 3d-essentials for 3D terrain meshes, math-essentials for vectors and transforms, godot-optimization for chunk loading and performance.
1. Seeded Randomness
Always use seeds for reproducible generation. This enables shareable seeds, replay, and deterministic testing.
GDScript
# RandomNumberGenerator — per-instance, seedable
var rng := RandomNumberGenerator.new()
func generate_level(level_seed: int) -> void:
rng.seed = level_seed
var width: int = rng.randi_range(20, 40)
var height: int = rng.randi_range(15, 30)
var enemy_count: int = rng.randi_range(3, 8)
var treasure_chance: float = rng.randf_range(0.05, 0.15)
# AVOID: Global randf()/randi() — not reproducible across calls
# USE: rng.randf(), rng.randi(), rng.randf_range(), rng.randi_range()
C#
private RandomNumberGenerator _rng = new();
public void GenerateLevel(ulong levelSeed)
{
_rng.Seed = levelSeed;
int width = _rng.RandiRange(20, 40);
int height = _rng.RandiRange(15, 30);
int enemyCount = _rng.RandiRange(3, 8);
float treasureChance = _rng.RandfRange(0.05f, 0.15f);
}
Tip: Generate a seed from a string for shareable level codes:
var seed: int = "MyLevel".hash()
2. Noise-Based Generation (FastNoiseLite)
FastNoiseLite for height maps, biome distribution, 2D terrain. Key params: noise_type (Perlin / Simplex / Cellular / Value), frequency (lower = larger features), seed. For terrain, sample noise at each tile coord, threshold the value to pick a tile.
See references/noise-generation.md for the basic noise-map recipe, noise-type reference table, and 2D terrain + TileMapLayer walkthrough.
3. BSP Dungeon Generation
Binary Space Partitioning recursively splits a rectangle into smaller rectangles, carves a room inside each leaf, connects siblings with corridors. Produces grid-aligned room-based dungeons (think roguelike).
See references/bsp-dungeons.md for the full recursive partition + room placement + corridor connection algorithm in GDScript + C#.
4. Cellular Automata (Cave Generation)
Fill a grid with random walls/floors at ~45% density, then iterate "a cell becomes a wall if ≥ 5 of 8 neighbors are walls" 4-5 times. The result is organic cave shapes — no straight corridors.
See references/cellular-automata.md for the full GDScript + C# implementation with TileMapLayer integration.
5. Wave Function Collapse (WFC)
WFC is a constraint solver: given a tile set with adjacency rules, pick the lowest-entropy cell, collapse it to a valid tile, propagate constraints, repeat. Produces tile-rule-respecting output but is non-trivial to implement.
See references/wave-function-collapse.md for concept overview and a simplified GDScript + C# implementation.
6. Common Pitfalls
| Symptom | Cause | Fix |
|---|---|---|
| Same level every time | Not seeding the RNG | Set rng.seed before generation |
| Different results on different platforms | Using global randf() / randi() |
Use a dedicated RandomNumberGenerator instance |
| Noise looks blocky | Frequency too high | Lower frequency (try 0.01–0.05) |
| Caves are all wall or all floor | fill_chance too extreme or too few iterations |
Use fill_chance 0.40–0.50 and 4–6 iterations |
| BSP rooms overlap | Split position too close to edge | Ensure min_room_size buffer in split calculation |
| WFC contradiction (no valid tile) | Adjacency rules too restrictive | Add more allowed neighbors or implement backtracking |
| Generation takes too long | Processing entire map in one frame | Use await get_tree().process_frame to spread across frames, or use a thread |
7. Implementation Checklist
- All generation uses a seedable
RandomNumberGenerator, never globalrandf()/randi() - Seeds are stored with save data so levels can be reproduced
-
FastNoiseLitefrequency and octaves are tuned for the game's tile/world scale - Large generation is spread across frames or run on a thread to avoid freezing
- Generated TileMapLayer content uses terrain autotiling when possible (not hardcoded tile coords)
- BSP dungeons verify all rooms are connected before finalizing
- Cave generation runs a flood-fill to ensure reachability between key points
- Player spawn point is validated to be on a floor tile, not inside a wall