import { Vector2 } from "three";
import type { Vector2Like } from "../math";
import { UIProgressMaskFunction } from "./UIProgressMaskFunction";
/** Linear directional progress fill */
export declare class UIProgressMaskFunctionDirectional extends UIProgressMaskFunction {
    /** Fill direction as normalized vector */
    readonly direction: Vector2;
    private readonly cachedDirection;
    /**
     * Creates directional mask function.
     *
     * @param direction - Fill direction vector. Automatically normalized.
     */
    constructor(direction?: Vector2Like);
    private ensureDirectionNormalized;
}