02Equalizer Bars Driven by a Synthetic Waveform Value

<svg width="0" height="0" style="position:absolute" aria-hidden="true">
  <defs>
    <symbol id="ico-play" viewBox="0 0 256 256"><g fill="currentColor"><path d="M228.23 134.69L84.15 222.81A8 8 0 0 1 72 216.12V39.88a8 8 0 0 1 12.15-6.69l144.08 88.12a7.82 7.82 0 0 1 0 13.38" opacity=".2"/><path d="M232.4 114.49L88.32 26.35a16 16 0 0 0-16.2-.3A15.86 15.86 0 0 0 64 39.87v176.26A15.94 15.94 0 0 0 80 232a16.07 16.07 0 0 0 8.36-2.35l144.04-88.14a15.81 15.81 0 0 0 0-27ZM80 215.94V40l143.83 88Z"/></g></symbol>
    <symbol id="ico-pause" viewBox="0 0 256 256"><g fill="currentColor"><path d="M208 48v160a8 8 0 0 1-8 8h-40a8 8 0 0 1-8-8V48a8 8 0 0 1 8-8h40a8 8 0 0 1 8 8M96 40H56a8 8 0 0 0-8 8v160a8 8 0 0 0 8 8h40a8 8 0 0 0 8-8V48a8 8 0 0 0-8-8" opacity=".2"/><path d="M200 32h-40a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h40a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 176h-40V48h40ZM96 32H56a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h40a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 176H56V48h40Z"/></g></symbol>
  </defs>
</svg>
<main class="stage">
<div class="eq is-demo is-playing" id="eq">
  <p class="eq__hint"><span>Press play and heights precomputed from sine curves sway each bar differently.</span></p>
  <div class="eq__panel">
    <button class="eq__play" id="play" type="button" aria-label="Play">
      <svg class="eq__ico eq__ico--play" aria-hidden="true"><use href="#ico-play"></use></svg>
      <svg class="eq__ico eq__ico--pause" aria-hidden="true"><use href="#ico-pause"></use></svg>
    </button>
    <div class="eq__bars" id="bars" aria-hidden="true"></div>
  </div>
</div>
</main>

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

// 계산 겹(사인 합성)은 index.html 의 synth()/render() 에 있다. 여기는 무대·레이아웃만.
$duration: $dur-base;
$easing:   $ease-out;
$color:    $subject-ink;

@include stage($stage-yellow);

.eq {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
  width: min(400px, 92vw);
}

.eq__hint {
  margin: 0;
  color: rgba($subject-ink, .78);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.eq__panel {
  width: 100%;
  border-radius: $r-card;
  background: rgba($subject-ink, .06);
  box-shadow: 0 0 0 1px rgba($subject-ink, .14);
  padding: $sp-6 $sp-5;
  display: flex;
  align-items: center;
  gap: $sp-5;
}

.eq__play {
  flex: 0 0 auto;
  width: $sp-10;
  height: $sp-10;
  border-radius: $r-pill;
  border: none;
  background: $color;
  color: $stage-yellow;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform $duration $easing;
}

.eq__play:hover { transform: scale(1.06); }
.eq__play:focus-visible { outline: 2px solid $subject-ink; outline-offset: 2px; }
.eq__play:active { transform: scale(.96); }

.eq__ico { width: 18px; height: 18px; }
.eq__ico--pause { display: none; }
.is-playing .eq__ico--play { display: none; }
.is-playing .eq__ico--pause { display: block; }

.eq__bars {
  flex: 1 1 auto;
  height: 88px;
  display: flex;
  align-items: flex-end;
  gap: 4px;
}

.eq__bar {
  flex: 1 1 auto;
  height: 100%;
  border-radius: $r-xs $r-xs 0 0;
  background: $color;
  opacity: .82;
  transform: scaleY(.14);
  transform-origin: bottom center; // 막대는 바닥이 실제 앵커 — 중심 기준이 아니다
}

@media (max-width: 340px) {
  .eq__panel { padding: $sp-4 $sp-3; gap: $sp-3; }
  .eq__play { width: $sp-8; height: $sp-8; }
  .eq__ico { width: 15px; height: 15px; }
  .eq__bars { height: 64px; }
}

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

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.eq {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: min(400px, 92vw);
}

.eq__hint {
  margin: 0;
  color: rgba(23, 20, 26, 0.78);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.eq__panel {
  width: 100%;
  border-radius: 16px;
  background: rgba(23, 20, 26, 0.06);
  box-shadow: 0 0 0 1px rgba(23, 20, 26, 0.14);
  padding: 24px 20px;
  display: flex;
  align-items: center;
  gap: 20px;
}

.eq__play {
  flex: 0 0 auto;
  width: 40px;
  height: 40px;
  border-radius: 999px;
  border: none;
  background: #17141a;
  color: #ffd23f;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 300ms ease-out;
}

.eq__play:hover {
  transform: scale(1.06);
}

.eq__play:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 2px;
}

.eq__play:active {
  transform: scale(0.96);
}

.eq__ico {
  width: 18px;
  height: 18px;
}

.eq__ico--pause {
  display: none;
}

.is-playing .eq__ico--play {
  display: none;
}

.is-playing .eq__ico--pause {
  display: block;
}

.eq__bars {
  flex: 1 1 auto;
  height: 88px;
  display: flex;
  align-items: flex-end;
  gap: 4px;
}

.eq__bar {
  flex: 1 1 auto;
  height: 100%;
  border-radius: 4px 4px 0 0;
  background: #17141a;
  opacity: 0.82;
  transform: scaleY(0.14);
  transform-origin: bottom center;
}

@media (max-width: 340px) {
  .eq__panel {
    padding: 16px 12px;
    gap: 12px;
  }
  .eq__play {
    width: 32px;
    height: 32px;
  }
  .eq__ico {
    width: 15px;
    height: 15px;
  }
  .eq__bars {
    height: 64px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .eq__play {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('eq');
  var playBtn = document.getElementById('play');
  var barsEl = document.getElementById('bars');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var isDemo = true;

  // 결정론 난수 — Math.random 을 쓰지 않는다. LCG(선형합동생성기) 하나로 막대별 위상·진폭을 만든다.
  function makeLcg(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }

  var BAR_COUNT = 20;
  var rng = makeLcg(2909);
  var bars = [];
  for (var i = 0; i < BAR_COUNT; i++) {
    bars.push({
      el: null,
      // 사인 곡선 두 겹을 겹쳐 막대마다 다른 위상·주파수로 높이를 합성한다 — 291 편처럼 AudioContext/AnalyserNode 로
      // 실제 소리를 분석해 얻는 값이 아니라, 여기서는 사인 합성만으로 만든 장식용 값이다.
      f1: 0.55 + rng() * 0.35,
      p1: rng() * Math.PI * 2,
      f2: 1.4 + rng() * 0.6,
      p2: rng() * Math.PI * 2,
      w2: 0.25 + rng() * 0.2,
      idle: 0.14 + rng() * 0.08
    });
  }

  for (var i = 0; i < BAR_COUNT; i++) {
    var b = document.createElement('div');
    b.className = 'eq__bar';
    barsEl.appendChild(b);
    bars[i].el = b;
  }

  function synth(bar, tSec) {
    var s1 = Math.sin(tSec * bar.f1 * Math.PI * 2 + bar.p1);
    var s2 = Math.sin(tSec * bar.f2 * Math.PI * 2 + bar.p2) * bar.w2;
    var v = (s1 + s2) / (1 + bar.w2); // -1..1 범위로 정규화
    return 0.5 + v * 0.5; // 0..1
  }

  function human() { if (isDemo) { root.classList.remove('is-demo'); isDemo = false; } }

  var playing = true, t0 = 0;

  function render(now, playingNow) {
    var tSec = (now - t0) / 1000;
    for (var i = 0; i < BAR_COUNT; i++) {
      var bar = bars[i];
      var h = playingNow ? synth(bar, tSec) : bar.idle;
      // 막대는 바닥이 기준점이라 아래쪽 원점으로 세로로만 자란다 — 중심 기준이 아닌 실제 앵커 지점
      bar.el.style.transform = 'scaleY(' + Math.max(0.06, h) + ')';
    }
  }

  function setPlaying(next) {
    playing = next;
    root.classList.toggle('is-playing', next);
  }

  function onPlayClick() { human(); setPlaying(!playing); }
  function onPlayKeydown(e) {
    if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); human(); setPlaying(!playing); }
  }

  function frame(now) {
    if (!t0) t0 = now;
    render(now, isDemo ? true : playing);
    requestAnimationFrame(frame);
  }

  if (reduce) {
    root.classList.add('is-still');
    t0 = performance.now();
    render(t0, false);
    playBtn.addEventListener('click', function () {
      human(); setPlaying(!playing);
      render(performance.now(), playing);
    });
    playBtn.addEventListener('keydown', function (e) {
      if (e.key === 'Enter' || e.key === ' ') {
        e.preventDefault(); human(); setPlaying(!playing);
        render(performance.now(), playing);
      }
    });
  } else {
    playBtn.addEventListener('click', onPlayClick);
    playBtn.addEventListener('keydown', onPlayKeydown);
    requestAnimationFrame(frame);
  }
})();

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

type Bar = { el: HTMLDivElement | null; f1: number; p1: number; f2: number; p2: number; w2: number; idle: number };

export default function WaveformBars() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const playRef = useRef<HTMLButtonElement | null>(null);
  const barsElRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const playBtn = playRef.current;
    const barsEl = barsElRef.current;
    if (!root || !playBtn || !barsEl) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let isDemo = true;

    // 결정론 난수 — Math.random 을 쓰지 않는다. LCG(선형합동생성기) 하나로 막대별 위상·진폭을 만든다.
    function makeLcg(seed: number) {
      let s = seed >>> 0;
      return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
    }

    const BAR_COUNT = 20;
    const rng = makeLcg(2909);
    const bars: Bar[] = [];
    for (let i = 0; i < BAR_COUNT; i++) {
      bars.push({
        el: null,
        // 사인 곡선 두 겹을 겹쳐 막대마다 다른 위상·주파수로 높이를 합성한다 — 291 편처럼 AudioContext/AnalyserNode 로
        // 실제 소리를 분석해 얻는 값이 아니라, 여기서는 사인 합성만으로 만든 장식용 값이다.
        f1: 0.55 + rng() * 0.35,
        p1: rng() * Math.PI * 2,
        f2: 1.4 + rng() * 0.6,
        p2: rng() * Math.PI * 2,
        w2: 0.25 + rng() * 0.2,
        idle: 0.14 + rng() * 0.08,
      });
    }

    for (let i = 0; i < BAR_COUNT; i++) {
      const b = document.createElement("div");
      b.className = styles.bar;
      barsEl.appendChild(b);
      bars[i].el = b;
    }

    function synth(bar: Bar, tSec: number) {
      const s1 = Math.sin(tSec * bar.f1 * Math.PI * 2 + bar.p1);
      const s2 = Math.sin(tSec * bar.f2 * Math.PI * 2 + bar.p2) * bar.w2;
      const v = (s1 + s2) / (1 + bar.w2); // -1..1 범위로 정규화
      return 0.5 + v * 0.5; // 0..1
    }

    function human() { if (isDemo) { root!.classList.remove(styles["is-demo"]); isDemo = false; } }

    let playing = true, t0 = 0;

    function render(now: number, playingNow: boolean) {
      const tSec = (now - t0) / 1000;
      for (let i = 0; i < BAR_COUNT; i++) {
        const bar = bars[i];
        const h = playingNow ? synth(bar, tSec) : bar.idle;
        // 막대는 바닥이 기준점이라 아래쪽 원점으로 세로로만 자란다 — 중심 기준이 아닌 실제 앵커 지점
        bar.el!.style.transform = "scaleY(" + Math.max(0.06, h) + ")";
      }
    }

    function setPlaying(next: boolean) {
      playing = next;
      root!.classList.toggle(styles["is-playing"], next);
    }

    function onPlayClick() { human(); setPlaying(!playing); }
    function onPlayKeydown(e: KeyboardEvent) {
      if (e.key === "Enter" || e.key === " ") { e.preventDefault(); human(); setPlaying(!playing); }
    }

    let raf = 0;
    function frame(now: number) {
      if (!t0) t0 = now;
      render(now, isDemo ? true : playing);
      raf = requestAnimationFrame(frame);
    }

    function onReduceClick() { human(); setPlaying(!playing); render(performance.now(), playing); }
    function onReduceKeydown(e: KeyboardEvent) {
      if (e.key === "Enter" || e.key === " ") {
        e.preventDefault(); human(); setPlaying(!playing); render(performance.now(), playing);
      }
    }

    if (reduce) {
      root.classList.add(styles["is-still"]);
      t0 = performance.now();
      render(t0, false);
      playBtn.addEventListener("click", onReduceClick);
      playBtn.addEventListener("keydown", onReduceKeydown);
    } else {
      playBtn.addEventListener("click", onPlayClick);
      playBtn.addEventListener("keydown", onPlayKeydown);
      raf = requestAnimationFrame(frame);
    }

    return () => {
      cancelAnimationFrame(raf);
      if (reduce) {
        playBtn.removeEventListener("click", onReduceClick);
        playBtn.removeEventListener("keydown", onReduceKeydown);
      } else {
        playBtn.removeEventListener("click", onPlayClick);
        playBtn.removeEventListener("keydown", onPlayKeydown);
      }
      barsEl.innerHTML = "";
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.eq + " " + styles["is-demo"] + " " + styles["is-playing"]} ref={rootRef}>
        <p className={styles.hint}><span>재생을 누르면 사인 곡선으로 미리 계산한 높이 값이 막대마다 다르게 흔들립니다</span></p>
        <div className={styles.panel}>
          <button className={styles.play} ref={playRef} type="button" aria-label="재생">
            <svg className={`${styles.ico} ${styles.icoPlay}`} aria-hidden="true"><use href="#ico-play" /></svg>
            <svg className={`${styles.ico} ${styles.icoPause}`} aria-hidden="true"><use href="#ico-pause" /></svg>
          </button>
          <div className={styles.bars} ref={barsElRef} aria-hidden="true" />
        </div>
      </div>
    </main>
  );
}