06質量値による押し込み速度差 — 決めた質量の値が大きいほど押し込みと復帰の速度の値が遅くなる方式

<main class="stage">
<div class="bwm is-demo" id="bwm">
  <div class="bwm__row">
    <button class="bwm__btn" id="bwmLight" data-mass="light" type="button">軽い</button>
    <button class="bwm__btn" id="bwmMedium" data-mass="medium" type="button">普通</button>
    <button class="bwm__btn" id="bwmHeavy" data-mass="heavy" type="button">重い</button>
  </div>
  <p class="bwm__hint">押してみると、決めた質量の値が大きいほどゆっくり動きます</p>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// 계산 겹(질량별 스프링 적분)은 JS 에 있다 — 여기는 정적 배치만.
@include stage($stage-paper);

.stage { position: relative; }

.bwm {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-4;
}

.bwm__row {
  display: flex;
  gap: $sp-4;
}

.bwm__btn {
  border: 0;
  border-radius: $r-control;
  padding: $sp-4 $sp-5;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: $shadow-raised;
}

.bwm__hint {
  color: rgba($subject-ink, .72);
  font-size: 12px;
  text-align: center;
  max-width: 260px;
}

@media (max-width: 340px) {
  .bwm__row { gap: $sp-2; }
  .bwm__btn { padding: $sp-3 $sp-3; font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  .bwm__btn { transition: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.stage {
  position: relative;
}

.bwm {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.bwm__row {
  display: flex;
  gap: 16px;
}

.bwm__btn {
  border: 0;
  border-radius: 12px;
  padding: 16px 20px;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.bwm__hint {
  color: rgba(23, 20, 26, 0.72);
  font-size: 12px;
  text-align: center;
  max-width: 260px;
}

@media (max-width: 340px) {
  .bwm__row {
    gap: 8px;
  }
  .bwm__btn {
    padding: 12px 12px;
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .bwm__btn {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('bwm');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  // 계산 겹: 세 버튼은 같은 스프링 상수 K·감쇠 C 를 쓰지만 질량 값(MASS)이 다르다.
  // accel = -(K/MASS)*(depth-target) - (C/MASS)*vel — MASS 가 클수록 같은 힘에서 가속도가
  // 작아져(뉴턴 F=ma) 눌리고 돌아오는 속도가 함께 느려진다.
  var K = 320, C = 8, PRESS_DEPTH = 12;
  var MASS = { light: 0.5, medium: 1.4, heavy: 3.6 };

  function makeBtn(el, key) {
    return { el: el, mass: MASS[key], depth: 0, vel: 0, target: 0 };
  }
  var items = [
    makeBtn(document.getElementById('bwmLight'), 'light'),
    makeBtn(document.getElementById('bwmMedium'), 'medium'),
    makeBtn(document.getElementById('bwmHeavy'), 'heavy')
  ];
  var last = 0, raf = null;

  function paint(it) { it.el.style.transform = 'translateY(' + it.depth.toFixed(2) + 'px)'; }
  function tick(now) {
    var dt = Math.min((now - last) / 1000, 0.032);
    last = now;
    for (var i = 0; i < items.length; i++) {
      var it = items[i];
      var accel = (-K * (it.depth - it.target) - C * it.vel) / it.mass;
      it.vel += accel * dt;
      it.depth += it.vel * dt;
      paint(it);
    }
    raf = requestAnimationFrame(tick);
  }
  function start() { if (raf === null) { last = performance.now(); raf = requestAnimationFrame(tick); } }
  function press(it, p) {
    if (reduce) { it.depth = p; it.vel = 0; it.target = p; paint(it); return; }
    it.target = p;
    start();
  }

  function wireReal() {
    items.forEach(function (it) {
      it.el.addEventListener('pointerdown', function () { root.classList.remove('is-demo'); stopAutoplay(); press(it, PRESS_DEPTH); });
      it.el.addEventListener('pointerup', function () { press(it, 0); });
      it.el.addEventListener('pointercancel', function () { press(it, 0); });
    });
  }
  wireReal();
  items.forEach(paint);

  // 자동 루프: 세 버튼을 동시에 눌렀다 동시에 떼어, 같은 힘에서 질량별 속도 차이를 나란히 보여준다.
  var autoTimer = null, autoDown = null;
  function autoTick() {
    items.forEach(function (it) { press(it, PRESS_DEPTH); });
    autoDown = setTimeout(function () { items.forEach(function (it) { press(it, 0); }); }, 300);
  }
  function stopAutoplay() {
    if (autoTimer) { clearInterval(autoTimer); autoTimer = null; }
    if (autoDown) { clearTimeout(autoDown); autoDown = null; }
  }
  if (!reduce) { autoTick(); autoTimer = setInterval(autoTick, 1700); }
})();

import { useEffect, useRef } from "react";
import styles from "./ButtonPhysicsWeightMassPressDepth.module.scss";

export type ButtonPhysicsWeightMassPressDepthProps = {
  color?: string;
};

type MassKey = "light" | "medium" | "heavy";
type MassItem = { el: HTMLButtonElement; mass: number; depth: number; vel: number; target: number };

export default function ButtonPhysicsWeightMassPressDepth({
  color = "#0a4fe8",
}: ButtonPhysicsWeightMassPressDepthProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const lightEl = root.querySelector<HTMLButtonElement>(`.${styles.light}`);
    const mediumEl = root.querySelector<HTMLButtonElement>(`.${styles.medium}`);
    const heavyEl = root.querySelector<HTMLButtonElement>(`.${styles.heavy}`);
    if (!lightEl || !mediumEl || !heavyEl) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    // 계산 겹: 세 버튼은 같은 스프링 상수 K·감쇠 C 를 쓰지만 질량 값(MASS)이 다르다.
    // accel = -(K/MASS)*(depth-target) - (C/MASS)*vel — MASS 가 클수록 같은 힘에서 가속도가
    // 작아져(뉴턴 F=ma) 눌리고 돌아오는 속도가 함께 느려진다.
    const K = 320, C = 8, PRESS_DEPTH = 12;
    const MASS: Record<MassKey, number> = { light: 0.5, medium: 1.4, heavy: 3.6 };

    function makeBtn(el: HTMLButtonElement, key: MassKey): MassItem {
      return { el, mass: MASS[key], depth: 0, vel: 0, target: 0 };
    }
    const items: MassItem[] = [
      makeBtn(lightEl, "light"),
      makeBtn(mediumEl, "medium"),
      makeBtn(heavyEl, "heavy"),
    ];
    let last = 0, raf: number | null = null;

    function paint(it: MassItem) { it.el.style.transform = "translateY(" + it.depth.toFixed(2) + "px)"; }
    function tick(now: number) {
      const dt = Math.min((now - last) / 1000, 0.032);
      last = now;
      for (let i = 0; i < items.length; i++) {
        const it = items[i];
        const accel = (-K * (it.depth - it.target) - C * it.vel) / it.mass;
        it.vel += accel * dt;
        it.depth += it.vel * dt;
        paint(it);
      }
      raf = requestAnimationFrame(tick);
    }
    function start() { if (raf === null) { last = performance.now(); raf = requestAnimationFrame(tick); } }
    function press(it: MassItem, p: number) {
      if (reduce) { it.depth = p; it.vel = 0; it.target = p; paint(it); return; }
      it.target = p;
      start();
    }

    const cleanups: Array<() => void> = [];
    items.forEach((it) => {
      const onDown = () => { stopAutoplay(); press(it, PRESS_DEPTH); };
      const onUp = () => { press(it, 0); };
      it.el.addEventListener("pointerdown", onDown);
      it.el.addEventListener("pointerup", onUp);
      it.el.addEventListener("pointercancel", onUp);
      cleanups.push(() => {
        it.el.removeEventListener("pointerdown", onDown);
        it.el.removeEventListener("pointerup", onUp);
        it.el.removeEventListener("pointercancel", onUp);
      });
    });
    items.forEach(paint);

    let autoTimer: number | null = null, autoDown: number | null = null;
    function autoTick() {
      items.forEach((it) => { press(it, PRESS_DEPTH); });
      autoDown = window.setTimeout(() => { items.forEach((it) => { press(it, 0); }); }, 300);
    }
    function stopAutoplay() {
      if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; }
      if (autoDown !== null) { window.clearTimeout(autoDown); autoDown = null; }
    }
    if (!reduce) { autoTick(); autoTimer = window.setInterval(autoTick, 1700); }

    return () => {
      stopAutoplay();
      if (raf !== null) cancelAnimationFrame(raf);
      cleanups.forEach((fn) => fn());
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.bwm}>
        <div className={styles.row}>
          <button className={`${styles.btn} ${styles.light}`} type="button" style={{ background: color }}>가벼움</button>
          <button className={`${styles.btn} ${styles.medium}`} type="button" style={{ background: color }}>보통</button>
          <button className={`${styles.btn} ${styles.heavy}`} type="button" style={{ background: color }}>무거움</button>
        </div>
        <p className={styles.hint}>눌러보면 정해둔 질량 값이 클수록 더 느리게 움직입니다</p>
      </div>
    </div>
  );
}