function decay({ velocity = 0, from = 0, power = 0.8, timeConstant = 350, restDelta = 0.5, modifyTarget, }) {
    const state = { done: false, value: from };
    let amplitude = power * velocity;
    const ideal = from + amplitude;
    const target = modifyTarget === undefined ? ideal : modifyTarget(ideal);
    if (target !== ideal)
        amplitude = target - from;
    return {
        next: (t) => {
            const delta = -amplitude * Math.exp(-t / timeConstant);
            state.done = !(delta > restDelta || delta < -restDelta);
            state.value = state.done ? target : target + delta;
            return state;
        },
        flipTarget: () => { },
    };
}

export { decay };