import { Entity, System } from '@lastolivegames/becsy';
export declare function sortByFractionalIndex(a?: Entity | string, b?: Entity | string): 0 | 1 | -1;
/**
 * Sort entities by z-index under context.
 *
 * @see https://infinitecanvas.cc/guide/lesson-014#z-index
 */
export declare class Sort extends System {
    private renderables;
    private fractionalIndexes;
    constructor();
    execute(): void;
}