01Team hero — a photo row whose entrance delay is computed from headcount

<main class="stage">
<section class="hero" id="hero">
  <p class="hero__hint" id="heroHint">The stagger interval compresses to fit the headcount, using only the moment the section enters the viewport as its reference.</p>
  <div class="hero__row" id="heroRow" aria-label="Team photo row" role="list">
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M1</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M2</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M3</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M4</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M5</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M6</span></div>
    <div class="hero__avatar" role="listitem"><canvas class="hero__cv" width="48" height="48" aria-hidden="true"></canvas><span class="hero__tag">M7</span></div>
  </div>
  <p class="hero__meta"><span class="hero__chip" id="heroChip">n=5 · step 96ms</span></p>
</section>
</main>

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

$duration: $dur-enter;        // 600ms — 등장 트랜지션
$easing: $ease-spring;
$color: $subject-blue-deep;

@include stage($stage-ink);

.hero {
  width: 100%;
  max-width: 420px;
  display: flex;
  flex-direction: column;
  gap: $sp-3;
  align-items: center;
  text-align: center;
}

.hero__hint {
  margin: 0;
  padding: 0 $sp-2;
  font-weight: 400;
  font-size: 11px;
  line-height: 1.4;
  color: rgba($subject-cream, .72);
}

.hero__row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: $sp-2;
  width: 100%;
}

.hero__avatar {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-1;
  opacity: 0;
  transform: translateY($sp-4);
  transition: opacity $dur-quick $ease-out, transform $duration $easing;
  transition-delay: var(--delay, 0ms);
}

.hero__row.is-in .hero__avatar {
  opacity: 1;
  transform: translateY(0);
}

.hero__cv {
  display: block;
  width: 48px;
  height: 48px;
  border-radius: $r-pill;
  box-shadow: $shadow-press;
}

.hero__tag {
  font-weight: 500;
  font-size: 9px;
  color: rgba($subject-cream, .72);
}

.hero__meta {
  margin: 0;
}

.hero__chip {
  display: inline-flex;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: $color;
  color: $subject-cream;
  font-weight: 700;
  font-size: 11px;
}

@media (max-width: 340px) {
  .hero { max-width: 300px; gap: $sp-2; }
  .hero__hint { font-size: 9px; }
  .hero__row { gap: $sp-1; }
  .hero__cv { width: 36px; height: 36px; }
  .hero__tag { font-size: 8px; }
  .hero__chip { font-size: 10px; padding: $sp-1 $sp-2; }
}

@media (prefers-reduced-motion: reduce) {
  .hero__avatar {
    transition: none;
    opacity: 1;
    transform: none;
  }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.hero {
  width: 100%;
  max-width: 420px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
  text-align: center;
}

.hero__hint {
  margin: 0;
  padding: 0 8px;
  font-weight: 400;
  font-size: 11px;
  line-height: 1.4;
  color: rgba(255, 247, 230, 0.72);
}

.hero__row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  width: 100%;
}

.hero__avatar {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 220ms ease-out, transform 600ms cubic-bezier(0.2, 0.8, 0.2, 1);
  transition-delay: var(--delay, 0ms);
}

.hero__row.is-in .hero__avatar {
  opacity: 1;
  transform: translateY(0);
}

.hero__cv {
  display: block;
  width: 48px;
  height: 48px;
  border-radius: 999px;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.hero__tag {
  font-weight: 500;
  font-size: 9px;
  color: rgba(255, 247, 230, 0.72);
}

.hero__meta {
  margin: 0;
}

.hero__chip {
  display: inline-flex;
  padding: 4px 12px;
  border-radius: 999px;
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 700;
  font-size: 11px;
}

@media (max-width: 340px) {
  .hero {
    max-width: 300px;
    gap: 8px;
  }
  .hero__hint {
    font-size: 9px;
  }
  .hero__row {
    gap: 4px;
  }
  .hero__cv {
    width: 36px;
    height: 36px;
  }
  .hero__tag {
    font-size: 8px;
  }
  .hero__chip {
    font-size: 10px;
    padding: 4px 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .hero__avatar {
    transition: none;
    opacity: 1;
    transform: none;
  }
}

// 팀 히어로(01) — IntersectionObserver 로 섹션이 화면에 들어온 시점 하나만 기준을 잡고,
// 등장 예산(ENTRANCE_MS)을 그 순간의 인원수로 나눠 인덱스마다 곱하는 간격(step)을 매번 계산한다.
// 인원이 늘어도 등장 예산은 고정이라 총 등장 시간이 무한히 늘지 않는다(계산 한 겹).
// 자동 시연은 인원수를 5·7·4·6 으로 순환시켜 매번 다시 계산되는 것을 보여준다.
(function () {
  var hero = document.getElementById('hero');
  var row = document.getElementById('heroRow');
  var chip = document.getElementById('heroChip');
  if (!hero || !row || !chip) return;
  var avatars = Array.prototype.slice.call(row.querySelectorAll('.hero__avatar'));
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  function mulberry32(a) {
    return function () {
      a |= 0; a = a + 0x6D2B79F5 | 0;
      var t = Math.imul(a ^ a >>> 15, 1 | a);
      t = t + Math.imul(t ^ t >>> 7, 61 | t) ^ t;
      return ((t ^ t >>> 14) >>> 0) / 4294967296;
    };
  }

  var HEXES = ['#9fc9ec', '#93d9c0', '#b9a0ff', '#f6c6d3'];

  function drawAvatar(cv, seed, label) {
    var ctx = cv.getContext('2d');
    if (!ctx) return;
    var rnd = mulberry32(seed);
    var s = cv.width;
    ctx.clearRect(0, 0, s, s);
    ctx.save();
    ctx.beginPath(); ctx.arc(s / 2, s / 2, s / 2, 0, Math.PI * 2); ctx.clip();
    var cell = 8;
    for (var y = 0; y < s; y += cell) {
      for (var x = 0; x < s; x += cell) {
        var v = rnd();
        ctx.fillStyle = v > .5 ? HEXES[Math.floor(rnd() * HEXES.length)] : 'rgba(23,20,26,.10)';
        ctx.fillRect(x, y, cell, cell);
      }
    }
    ctx.restore();
    ctx.fillStyle = 'rgba(23,20,26,.55)';
    ctx.beginPath(); ctx.arc(s / 2, s / 2, s / 2, 0, Math.PI * 2); ctx.fill();
    ctx.fillStyle = '#fff7e6';
    ctx.font = '700 ' + Math.round(s * .38) + 'px -apple-system, "Segoe UI", sans-serif';
    ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
    ctx.fillText(label, s / 2, s / 2 + 1);
  }

  avatars.forEach(function (el, i) {
    var cv = el.querySelector('.hero__cv');
    if (cv) drawAvatar(cv, 31 + i * 17, 'M' + (i + 1));
  });

  var ENTRANCE_MS = 480;   // 등장 예산 — 인원수와 무관하게 고정
  var counts = [5, 7, 4, 6];
  var idx = 0;

  // 등장 간격 계산 — 예산을 이번 인원수로 나눈 몫이 step, 인덱스를 인원수로 나눈 나머지로
  // 매 순환마다 압축 폭을 다시 맞춘다(headcount 가 바뀌어도 같은 공식 재사용)
  function layout(count) {
    var step = ENTRANCE_MS / count;
    avatars.forEach(function (el, i) {
      var visible = i < count;
      el.style.display = visible ? '' : 'none';
      if (visible) el.style.setProperty('--delay', ((i % count) * step).toFixed(1) + 'ms');
    });
    chip.textContent = 'n=' + count + ' · step ' + Math.round(step) + 'ms';
    row.classList.remove('is-in');
    void row.offsetWidth;   // 강제 리플로우 — 트랜지션 재시작
    row.classList.add('is-in');
  }

  var fired = false;
  var io = new IntersectionObserver(function (entries) {
    entries.forEach(function (e) {
      if (e.isIntersecting && !fired) { fired = true; layout(counts[0]); }
    });
  }, { threshold: .3 });
  io.observe(hero);

  if (reduce) {
    layout(counts[0]);
  } else {
    layout(counts[0]);
    setInterval(function () {
      idx = (idx + 1) % counts.length;
      layout(counts[idx]);
    }, 650);
  }
})();

// TeamHero — vanilla 판(run/338/demo/01-team-hero/index.html) 의 React 포트.
// IntersectionObserver 로 섹션이 화면에 들어온 시점 하나만 기준을 잡고, 등장 예산(ENTRANCE_MS)을
// 그 순간의 인원수로 나눠 인덱스마다 곱하는 간격(step)을 매번 계산한다(계산 한 겹). 자동 시연은
// 인원수를 5·7·4·6 으로 순환시켜 매번 다시 계산되는 것을 보여준다.
import { useEffect, useRef } from "react";
import styles from "./TeamHero.module.scss";

export type TeamHeroProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

const HINT = "섹션이 화면에 들어온 시점 하나만 기준으로 인원수에 맞춰 등장 간격을 압축합니다";
const ROW_LABEL = "팀원 사진 줄";

function mulberry32(a: number): () => number {
  return function (): number {
    a |= 0; a = a + 0x6d2b79f5 | 0;
    let t = Math.imul(a ^ (a >>> 15), 1 | a);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

const HEXES = ["#9fc9ec", "#93d9c0", "#b9a0ff", "#f6c6d3"];
const ENTRANCE_MS = 480;
const COUNTS = [5, 7, 4, 6];
const MEMBER_MAX = 7;

function drawAvatar(cv: HTMLCanvasElement, seed: number, label: string): void {
  const ctx = cv.getContext("2d");
  if (!ctx) return;
  const rnd = mulberry32(seed);
  const s = cv.width;
  ctx.clearRect(0, 0, s, s);
  ctx.save();
  ctx.beginPath();
  ctx.arc(s / 2, s / 2, s / 2, 0, Math.PI * 2);
  ctx.clip();
  const cell = 8;
  for (let y = 0; y < s; y += cell) {
    for (let x = 0; x < s; x += cell) {
      const v = rnd();
      ctx.fillStyle = v > 0.5 ? HEXES[Math.floor(rnd() * HEXES.length)] : "rgba(23,20,26,.10)";
      ctx.fillRect(x, y, cell, cell);
    }
  }
  ctx.restore();
  ctx.fillStyle = "rgba(23,20,26,.55)";
  ctx.beginPath();
  ctx.arc(s / 2, s / 2, s / 2, 0, Math.PI * 2);
  ctx.fill();
  ctx.fillStyle = "#fff7e6";
  ctx.font = "700 " + Math.round(s * 0.38) + 'px -apple-system, "Segoe UI", sans-serif';
  ctx.textAlign = "center";
  ctx.textBaseline = "middle";
  ctx.fillText(label, s / 2, s / 2 + 1);
}

export default function TeamHero({
  duration = "600ms",
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#0a4fe8"
}: TeamHeroProps) {
  const heroRef = useRef<HTMLElement | null>(null);
  const rowRef = useRef<HTMLDivElement | null>(null);
  const chipRef = useRef<HTMLSpanElement | null>(null);

  useEffect(() => {
    const hero = heroRef.current;
    const row = rowRef.current;
    const chip = chipRef.current;
    if (!hero || !row || !chip) return;
    const avatars = Array.prototype.slice.call(row.querySelectorAll("." + styles.avatar)) as HTMLElement[];
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    avatars.forEach((el, i) => {
      const cv = el.querySelector("." + styles.cv) as HTMLCanvasElement | null;
      if (cv) drawAvatar(cv, 31 + i * 17, "M" + (i + 1));
    });

    function layout(count: number): void {
      const step = ENTRANCE_MS / count;
      avatars.forEach((el, i) => {
        const visible = i < count;
        el.style.display = visible ? "" : "none";
        if (visible) el.style.setProperty("--delay", ((i % count) * step).toFixed(1) + "ms");
      });
      chip!.textContent = "n=" + count + " · step " + Math.round(step) + "ms";
      row!.classList.remove(styles.rowIn);
      void row!.offsetWidth;
      row!.classList.add(styles.rowIn);
    }

    let fired = false;
    const io = new IntersectionObserver((entries) => {
      entries.forEach((e) => {
        if (e.isIntersecting && !fired) { fired = true; layout(COUNTS[0]); }
      });
    }, { threshold: 0.3 });
    io.observe(hero);

    let idx = 0;
    let timer = 0;
    if (reduce) {
      layout(COUNTS[0]);
    } else {
      layout(COUNTS[0]);
      timer = window.setInterval(() => {
        idx = (idx + 1) % COUNTS.length;
        layout(COUNTS[idx]);
      }, 650);
    }

    return () => {
      io.disconnect();
      if (timer) window.clearInterval(timer);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  const members = Array.from({ length: MEMBER_MAX }, (_, i) => i);

  return (
    <main className={styles.stage}>
      <section className={styles.hero} ref={heroRef}>
        <p className={styles.hint}>{HINT}</p>
        <div className={styles.row} ref={rowRef} role="list" aria-label={ROW_LABEL}>
          {members.map((i) => (
            <div className={styles.avatar} role="listitem" key={i}>
              <canvas className={styles.cv} width={48} height={48} aria-hidden="true" />
              <span className={styles.tag}>{"M" + (i + 1)}</span>
            </div>
          ))}
        </div>
        <p className={styles.meta}>
          <span className={styles.chip} ref={chipRef} style={{ background: color }}>n=5 · step 96ms</span>
        </p>
      </section>
    </main>
  );
}