import { SparseVoxelGrid } from './sparse-voxel-grid';
/**
 * Two-level BFS on a sparse voxel grid.
 *
 * Exploits the fact that most blocks in the blocked grid are BLOCK_EMPTY (all
 * 64 voxels free). When BFS reaches such a block, ALL voxels are reachable
 * (mutually face-connected within the 4x4x4 cube), so we mark the entire
 * block as visited and propagate at block granularity -- 64x fewer operations.
 *
 * Two queues:
 *   Block queue  -- processes BLOCK_EMPTY (in blocked) blocks at block level
 *   Voxel queue  -- processes individual voxels in BLOCK_MIXED blocks
 *
 * When the voxel BFS enters a BLOCK_EMPTY block it switches to block fill.
 * When block fill hits a BLOCK_MIXED neighbor it enqueues free face voxels.
 *
 * @param blocked - Sparse voxel grid marking blocked voxels.
 * @param blockSeeds - Block indices to seed block-level BFS from.
 * @param voxelSeeds - Voxel coordinates to seed voxel-level BFS from.
 * @param nx - Grid dimension X in voxels.
 * @param ny - Grid dimension Y in voxels.
 * @param nz - Grid dimension Z in voxels.
 * @param onBlockFilled - Optional progress callback receiving the running
 * count of whole-block fills. Throttled internally so callers can wire it
 * directly to a progress bar without worrying about per-block overhead.
 * @returns Sparse voxel grid marking all reachable voxels.
 */
declare function twoLevelBFS(blocked: SparseVoxelGrid, blockSeeds: number[], voxelSeeds: {
    ix: number;
    iy: number;
    iz: number;
}[], nx: number, ny: number, nz: number, onBlockFilled?: (count: number) => void): SparseVoxelGrid;
export { twoLevelBFS };