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Locks

Locks pin the inputs that a feature depends on, so rerolling everything else preserves that feature exactly. The Locks chip sits at the top of the Build panel.

  • Coastline — keeps the heightmap and waterline.
  • Rivers — keeps every river in place. Auto-locks Coastline.
  • Forests — keeps the forest layout.
  • Mountains — keeps the mountain ranges.
  • Settlements — keeps every city / town / village in the same spot with the same names.
  • Labels — keeps every printed label. Auto-locks settlements + style (label fonts come from the style).

A lock pins the inputs the feature depends on, which often pins inputs upstream too. Locking Rivers, for example, also auto-locks Coastline because rivers are derived from the heightmap.

The UI shows auto-locked features in a softer amber state so you can tell user-set locks from cascaded ones.

The cascade map:

Lock Also pins
Coastline Kind, water amount, terrain drama
Rivers Coastline + river amount
Forests Coastline + forest amount
Mountains Coastline + mountain amount
Settlements Coastline + climate-axis fields + rivers + settlement density
Labels Settlements-locked fields + label density + style

Inputs that are pinned get visibly disabled in the Build tool — you can’t change Water amount once Coastline is locked, for instance.

  1. Generate a map. When you find one you like, click the Lock chip for the feature you want to keep.

  2. Reroll, change the style, tweak sliders — anything that isn’t pinned by your lock is free.

  3. Generate again. The locked feature regenerates byte-identical because every input it depends on is pinned.

To release a lock, click its chip again. Toggling the first lock snapshots (seed, kind, settings); releasing the last lock releases the snapshot.

Lock Coastline. Hit Reroll. Same landmass, different cities.

Lock Settlements. Change Style in the Build tool. Same cities with the same names, new visual treatment.

Keep the whole map, only re-roll vegetation

Section titled “Keep the whole map, only re-roll vegetation”

Lock Settlements AND Mountains AND Rivers. Reroll. Only forests / biomes shift.

  • Aspect ratio and pixel size — canvas dimensions are never frozen because they re-sample the noise space.
  • Decorations (Decorate tool) — independent of generator inputs, kept across rerolls automatically.
  • Painted regions (Paint tool) — survive rerolls within the same seed but get cleared when the seed changes.
  • Build tool — fields disabled by an active lock.
  • Variations — uses locks to flip through alternative seeds while keeping the rest of your settings.