Nebula / Stars / StarsMult / StarsVariance are singletons — adding again replaces the existing one (matches the Sector.json schema, which has one slot each).
Mass Add (Asteroid Field)
Region shape
Click, then click+drag on the ground plane (Y=0) to set the X/Z bounds below. Esc cancels.
Region min (x, y, z)
Region max (x, y, z)
Click center, then drag out to set the radius. Esc cancels.
Center (x, z)
Radius (x, z)
Vacant center — 0 = solid disk, higher = thinner ring (e.g. 70 leaves a ring band from 70%–100% of the radius). Shown as a second outline while drawing.
Height range (min, max)
No outline set. Click "Draw outline", then click points in the viewport tracing any shape — scroll after each click to set that point's height. Finish (or Enter) when done, Esc cancels.
Height jitter (± around each point's traced height)
Scatters Count copies at random positions inside the region box (random prefab variant, random rotation, random radius in range — radius is data-only, doesn't affect preview size). Region is in the same preview-space coordinates as a single object's Position field. Capped at 2000 per click — large counts take a few seconds.
Scatters inert debris pieces (decoration only, not targetable) through the region, plus real content nearby: Cargo containers (individually lootable) scattered the same way, and one bot spawn area sized to the region with Drones worth of Ancient drone NPCs. This is what a real "debris field" is — the debris meshes alone are just scenery.