/**
 * Spherical nearest-tile lookup — shared spatial index used by every
 * caller that needs to map an arbitrary world-space point to its closest
 * tile on a hexasphere.
 *
 * The trick is a 2D azimuth × polar grid covering the unit sphere. Each
 * tile is binned into one cell at index time; queries scan the 3×3 cell
 * neighbourhood around the query direction. Polar rows wrap fully in
 * azimuth so the wrap-around at the poles is handled correctly.
 *
 * Cost is `O(k)` per query where `k` is the average tile count per cell
 * (≈ 36 for ~640 tiles), versus `O(T)` for a brute-force dot product
 * scan. Allocation-free on the hot path — typed-array buckets only.
 */
/** Minimal tile shape the lookup needs — accepts `Tile[]` directly. */
export interface SphericalIndexedTile {
    id: number;
    centerPoint: {
        x: number;
        y: number;
        z: number;
    };
}
/**
 * Builds a single-nearest lookup. Returns the tile id of the tile whose
 * unit-sphere centre is closest to the query direction (highest dot
 * product). Allocation-free per query.
 */
export declare function buildSphericalNearestLookup(tiles: readonly SphericalIndexedTile[]): (x: number, y: number, z: number) => number;
/**
 * Builds a top-K lookup. Writes K tile ids and their normalised blend
 * weights into caller-supplied typed arrays starting at `outOffset`,
 * so the caller can pre-allocate a single flat buffer of size `verts × K`
 * and the query path stays allocation-free.
 *
 * Weights are derived from `dot − dotKth` (offset against the K-th best)
 * then normalised to sum to 1; degenerate cases (all dots equal) collapse
 * to uniform `1/K`. This is the natural smooth-blend weighting for
 * vertex paint use cases — point-by-point queries can ignore the weight
 * output if they only need the ids.
 *
 * `k` is silently clamped to `tiles.length` when smaller; a tiles array
 * of length zero is a usage error and never expected.
 */
export declare function buildSphericalKNearestLookup(tiles: readonly SphericalIndexedTile[], k: number): (x: number, y: number, z: number, outIds: Int32Array, outWeights: Float32Array, outOffset: number) => void;
//# sourceMappingURL=sphericalTileLookup.d.ts.map