export type EaseFn = (t: number) => number;
export declare const ease: {
    readonly linear: (t: number) => number;
    readonly smoothstep: (t: number) => number;
};
export interface Tween {
    from: number;
    to: number;
    dur: number;
    ease: EaseFn;
    startMs: number;
    val: number;
    done: boolean;
}
export declare function tween(from: number, to: number, dur: number, e?: EaseFn): Tween;
export declare function tweenStart(tw: Tween, nowMs: number): void;
export declare function tweenTick(tw: Tween, nowMs: number): number;