import type { Vector2Like } from "../../core/miscellaneous/math";
import type { UIVector2Config } from "../miscellaneous/miscellaneous";
import { UIBehaviorModule } from "./UIBehaviorModule";
/**
 * Applies constant acceleration to all particles.
 *
 * Adds the direction vector to particle velocity each frame.
 */
export declare class UIBehaviorDirectionalGravity extends UIBehaviorModule<{
    builtin: "Matrix4";
}> {
    private directionInternal;
    /**
     * @param direction - Acceleration vector in units/second^2
     */
    constructor(direction: Vector2Like);
    /** Acceleration vector in units/second^2 */
    get direction(): Vector2Like;
    /** Acceleration vector in units/second^2 */
    set direction(value: UIVector2Config);
}