structuresNear method
The structures whose regions touch chunk (chunkX, chunkZ).
Implementation
List<PlacedStructure> structuresNear(int chunkX, int chunkZ) => [
for (final s in _structures)
for (final (rx, rz) in s.grid.around(chunkX, chunkZ)) ?_site(s.spec, s.grid, rx, rz),
];