ReadonlyobjectRoot group.
Resolved settings.
The shells as last drawn (altitudes in metres).
Frees GPU resources.
Places the shells around a planet and their labels for camera.
Planet centre, render space.
Planet radius, render units.
Resolved shells (see resolveShells).
Render units per metre (1 in the sky's frames, e.g. 1e-6 in a SolarSystem view).
The shell overlay.
Skyowns one (sky.shells, settings undershells); use it on its own with AltitudeShells.update.