ChunkFill

Fills one 8³ brick, the way an editMany fill callback does: cells holds the brick's 512 voxels (lx + ly8 + lz64), empty unless an earlier box of the same request already wrote to it, and (ox, oy, oz) is its world origin. Write the voxels and return true if anything changed.

type ChunkFill = (cells: Uint8Array, ox: number, oy: number, oz: number) => boolean;