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33 Tunnel

Motion · Imagery and depth
Tunnel

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motion-tunnel-fly-everything.md

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Prompt

1018 B
Tunnel — Z-axis tunnel fly-through

Stack six concentric square frames and send them past the viewer, as if flying into a tunnel from the centre.
Each frame is 40vmax square (sized on the screen's longer side, so even on a tall screen its edges clear the viewport before it fades), and its `scale` grows from 0.04 to 3.24 with `--p`, each frame starting 0.15 later than the one before.
Fade each frame in from opacity 0 to 1 as it appears and back to 0 as it passes, building depth from size differences alone without `translateZ`.
Use a 300vh section with a 100vh sticky box for the frames, implemented with CSS and plain JavaScript only; do not use a library.

Do not drop:
- Frames grow out from the centre and fade only after leaving the frame
- Depth comes from scale differences; never use translateZ (it renders unstably)
- With reduced motion, frames stay still in their stacked arrangement

A working example (one self-contained HTML file): https://design-vault.pages.dev/designs/motion-tunnel-fly/demo.html

Files

demo.html

8.0 KB

/designs/motion-tunnel-fly/demo.html — One self-contained HTML file. CSS and plain JavaScript only; it fetches nothing.

Show contents
<!doctype html>
<html lang="ja">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>33 トンネル — Z-axis tunnel fly-through</title>
<style>
/* dv-motion-base:start */
:root {
  --ground: #FFFFFF;
  --surface: #F3F5F8;
  --ink: #14181F;
  --muted: #5A6472;
  --accent: #1F5FA8;
  --rule: #D8DDE4;
  --accent-soft: color-mix(in srgb, var(--accent) 12%, var(--ground));
  --accent-mid: color-mix(in srgb, var(--accent) 45%, var(--ground));
  --shade: color-mix(in srgb, var(--ink) 14%, transparent);

  --font: "Zen Kaku Gothic New", "Hiragino Sans", "Noto Sans JP", "Yu Gothic", system-ui, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --t-label: 13px;
  --t-body: 16px;
  --t-lead: 20px;
  --t-h2: 32px;
  --t-h1: clamp(40px, 7vw, 72px);

  --s1: 4px;
  --s2: 8px;
  --s3: 16px;
  --s4: 24px;
  --s5: 40px;
  --s6: 64px;
  --s7: 104px;

  --radius: 12px;
  --ease: cubic-bezier(.2, .7, .2, 1);
  --dur: .7s;
  --measure: 1080px;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font-family: var(--font);
  font-size: var(--t-body);
  line-height: 1.7;
  font-feature-settings: "palt";
  overflow-x: hidden;
}
h1, h2, h3, p, ul, ol, figure { margin: 0; padding: 0; }
ul, ol { list-style: none; }
.dv-wrap { width: min(100% - 2 * var(--s4), var(--measure)); margin-inline: auto; }
.dv-label {
  min-height: 72vh;
  display: grid;
  align-content: center;
  gap: var(--s3);
  padding-block: var(--s6);
  border-bottom: 1px solid var(--rule);
}
.dv-num { font-family: var(--mono); font-size: var(--t-lead); font-weight: 700; color: var(--accent); letter-spacing: .04em; }
.dv-name { font-size: var(--t-h1); font-weight: 700; line-height: 1.15; letter-spacing: .01em; }
.dv-ai { font-family: var(--mono); font-size: var(--t-lead); color: var(--muted); }
.dv-desc { font-size: var(--t-lead); color: var(--ink); }
.dv-hint { font-size: var(--t-label); color: var(--muted); letter-spacing: .12em; margin-top: var(--s4); }
.dv-stage { padding-block: var(--s7); }
.dv-h2 { font-size: var(--t-h2); font-weight: 700; line-height: 1.3; }
.dv-lead { font-size: var(--t-lead); color: var(--muted); }
.dv-eyebrow { font-family: var(--mono); font-size: var(--t-label); color: var(--accent); letter-spacing: .12em; text-transform: uppercase; }
.dv-card { background: var(--surface); border: 1px solid var(--rule); border-radius: var(--radius); padding: var(--s4); }
.dv-ph {
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--accent-soft), var(--accent-mid) 60%, var(--accent));
  aspect-ratio: 16 / 9;
}
.dv-ph--alt { background: linear-gradient(200deg, var(--surface), var(--accent-soft) 55%, var(--accent-mid)); }
.dv-ph--ink { background: linear-gradient(160deg, var(--ink), color-mix(in srgb, var(--ink) 55%, var(--accent))); }
.dv-end {
  min-height: 60vh;
  display: grid;
  place-items: center;
  border-top: 1px solid var(--rule);
  color: var(--muted);
  font-family: var(--mono);
  font-size: var(--t-label);
  letter-spacing: .12em;
}
/* dv-motion-base:end */

/* ---- この演出だけの CSS。色は var(--…) か color-mix() のみ ---- */
.stack { display: grid; gap: var(--s6); }
.tunnel { height: 300vh; }
.tunnel-stick { position: sticky; top: 0; height: 100vh; overflow: hidden; background: var(--surface); }
.tunnel-frame {
  --q: clamp(0, calc(var(--p) * 1.8 - var(--i) * 0.15), 1);
  position: absolute; left: 50%; top: 50%;
  width: 40vmax; height: 40vmax;
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--accent) 6%, transparent);
  transform: translate(-50%, -50%) scale(calc(0.04 + var(--q) * 3.2));
  opacity: min(1, calc(var(--q) * 6), calc((0.9 - var(--q)) * 8));
}

@media (prefers-reduced-motion: reduce) {
  .tunnel-frame { transform: translate(-50%, -50%) scale(calc(0.3 + var(--i) * 0.14)); opacity: 1; }
}

</style>
</head>
<body data-motion-number="33">
<header class="dv-label">
  <div class="dv-wrap">
    <p class="dv-num">33</p>
    <h1 class="dv-name">トンネル</h1>
    <p class="dv-ai">Z-axis tunnel fly-through</p>
    <p class="dv-desc">奥へ飛び込むように層が迫る</p>
    <p class="dv-hint">SCROLL ↓</p>
  </div>
</header>

<main class="dv-stage">
  <div class="dv-wrap stack">
    <section class="dv-card">
      <p class="dv-eyebrow">Section 1</p>
      <h2 class="dv-h2">見出しが入ります</h2>
      <p class="dv-lead">本文のダミーです。スクロールすると、枠が奥から手前へ通り過ぎます。</p>
    </section>
  </div>

  <section class="tunnel" data-progress="pin">
    <div class="tunnel-stick">
      <div class="tunnel-frame" style="--i: 0"></div>
      <div class="tunnel-frame" style="--i: 1"></div>
      <div class="tunnel-frame" style="--i: 2"></div>
      <div class="tunnel-frame" style="--i: 3"></div>
      <div class="tunnel-frame" style="--i: 4"></div>
      <div class="tunnel-frame" style="--i: 5"></div>
    </div>
  </section>

  <div class="dv-wrap stack">
    <section class="dv-card">
      <p class="dv-eyebrow">Section 2</p>
      <h2 class="dv-h2">見出しが入ります</h2>
      <p class="dv-lead">本文のダミーです。枠が通り過ぎたあとに、この段落が続きます。</p>
    </section>
  </div>
</main>

<footer class="dv-end">END — 33 トンネル</footer>

<script>
/* dv-motion-helpers:start */
const dvReduce = matchMedia('(prefers-reduced-motion: reduce)').matches;
document.documentElement.classList.add('js');

/**
 * 画面に入った要素へ .is-in を付ける。
 * data-reveal="repeat" の要素は画面を出たら外す(何度でも再生)。
 */
function dvReveal(selector = '[data-reveal]', { threshold = 0.2, rootMargin = '0px 0px -8% 0px' } = {}) {
  const els = [...document.querySelectorAll(selector)];
  if (dvReduce || !('IntersectionObserver' in window)) {
    els.forEach((el) => el.classList.add('is-in'));
    return;
  }
  const io = new IntersectionObserver((entries) => {
    for (const e of entries) {
      if (e.isIntersecting) {
        e.target.classList.add('is-in');
        if (e.target.dataset.reveal !== 'repeat') io.unobserve(e.target);
      } else if (e.target.dataset.reveal === 'repeat') {
        e.target.classList.remove('is-in');
      }
    }
  }, { threshold, rootMargin });
  els.forEach((el) => io.observe(el));
}

/**
 * スクロール量を 0〜1 にして、各 [data-progress] 要素の CSS 変数 --p に書く。
 *   data-progress="through" : 要素の上端が画面の下端に来たとき 0、下端が画面の上端を抜けたとき 1
 *   data-progress="pin"     : 要素の上端が画面の上端に来たとき 0、下端が画面の下端に来たとき 1
 *                             (中に position: sticky の箱を持つ、背の高い区画用)
 *   data-progress="page"    : ページ全体のスクロール量
 * onUpdate(el, p) を渡すと、値が変わるたびに呼ばれる。
 */
function dvProgress(onUpdate) {
  const els = [...document.querySelectorAll('[data-progress]')];
  const clamp = (n) => Math.min(1, Math.max(0, n));
  let queued = false;
  const measure = () => {
    queued = false;
    const vh = window.innerHeight;
    for (const el of els) {
      const r = el.getBoundingClientRect();
      let p;
      if (el.dataset.progress === 'pin') p = r.height > vh ? -r.top / (r.height - vh) : 0;
      else if (el.dataset.progress === 'page') {
        const max = document.documentElement.scrollHeight - vh;
        p = max > 0 ? window.scrollY / max : 0;
      } else p = (vh - r.top) / (vh + r.height);
      p = clamp(p);
      el.style.setProperty('--p', p.toFixed(4));
      if (onUpdate) onUpdate(el, p);
    }
  };
  const request = () => {
    if (!queued) { queued = true; requestAnimationFrame(measure); }
  };
  addEventListener('scroll', request, { passive: true });
  addEventListener('resize', request);
  measure();
}
/* dv-motion-helpers:end */

/* ---- この演出だけの JS ---- */
dvProgress();
</script>
</body>
</html>

/ai/assets/motion-tunnel-fly.json