import type { Point2D } from '../../math';
export type Positioned = {
    cx: number;
    cy: number;
};
export type SpatialIndex<T extends Positioned> = {
    cells: Map<number, {
        item: T;
        idx: number;
    }[]>;
    cell_size: number;
    radius_px: number;
    count: number;
};
export declare function build_spatial_index<T extends Positioned>(items: Iterable<T>, radius_px: number): SpatialIndex<T>;
export declare function query_nearest<T extends Positioned>(index: SpatialIndex<T>, pointer: Point2D): T | null;