A still — with scripts on, it runs right here The demo itself — scroll inside the frame
A still — with scripts on, it runs right here The demo itself — scroll inside the frame
Copy and paste, or save a file and hand it over. For a machine with no network, one “Everything” file is enough.
Everything in this panel, including the contents behind each URL, in one Markdown file — Large, so it goes as a file (copy is for 32 KB and under)
Rotate on scroll — Rotate on scroll Place two meshing gears side by side and turn them with scroll. The left gear turns 360 degrees clockwise and the right gear 360 degrees counter-clockwise, at the same rate per unit of scroll. Draw each gear as an SVG `path` with 14 teeth, and offset the teeth of the right gear by half a pitch so that the teeth stay meshed while they turn. Make the section 300vh tall with a 100vh sticky box inside. Turn the gears only with `transform: rotate(calc(var(--p) * ±360deg))`, taking `--p` from the section's scroll progress. Implement with CSS and plain JavaScript only; do not use a library. Do not drop: - The two gears turn in opposite directions by the same amount (±360 degrees) - Both gears have 14 teeth and the offset is baked into the path, not applied by transform - Turn only with rotate(); never move or resize the gears - With reduced motion, the gears stay in their meshed starting position A working example (one self-contained HTML file): https://design-vault.pages.dev/designs/motion-rotate-on-scroll/demo.html
/designs/motion-rotate-on-scroll/demo.html — One self-contained HTML file. CSS and plain JavaScript only; it fetches nothing.
<!doctype html>
<html lang="ja">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>41 スクロール回転 — Rotate on scroll</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); }
/* 歯車は 2 枚とも歯数 14。歯の半ピッチずれは path の座標に焼いてあり、回転は rotate() だけ */
.gears { height: 300vh; }
.gears-stick { position: sticky; top: 0; height: 100vh; display: grid; place-items: center; overflow: hidden; }
.gears svg { width: min(100% - 2 * var(--s4), 560px); height: auto; display: block; }
.gear { fill: var(--accent); }
.hub, .mark { fill: var(--ground); }
.spin-a { transform-origin: 140px 120px; transform: rotate(calc(var(--p) * 360deg)); }
.spin-b { transform-origin: 306px 120px; transform: rotate(calc(var(--p) * -360deg)); }
@media (prefers-reduced-motion: reduce) {
.spin-a, .spin-b { transform: none; }
}
</style>
</head>
<body data-motion-number="41">
<header class="dv-label">
<div class="dv-wrap">
<p class="dv-num">41</p>
<h1 class="dv-name">スクロール回転</h1>
<p class="dv-ai">Rotate on scroll</p>
<p class="dv-desc">歯車や円盤がスクロールで回る</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。このあとの区画で、歯車がかみ合ったまま回ります。</p>
</section>
</div>
<section class="gears" data-progress="pin">
<div class="gears-stick">
<svg viewBox="40 20 366 200" role="img" aria-label="かみ合う 2 枚の歯車">
<g class="spin-a">
<path class="gear" d="M215.44 110.81L229.71 112.74L229.71 127.26L215.44 129.19L211.96 144.46L223.97 152.38L217.67 165.47L203.99 161.01L194.22 173.26L201.61 185.61L190.25 194.66L179.86 184.71L165.74 191.51L167.04 205.84L152.88 209.07L147.83 195.60L132.17 195.60L127.12 209.07L112.96 205.84L114.26 191.51L100.14 184.71L89.75 194.66L78.39 185.61L85.78 173.26L76.01 161.01L62.33 165.47L56.03 152.38L68.04 144.46L64.56 129.19L50.29 127.26L50.29 112.74L64.56 110.81L68.04 95.54L56.03 87.62L62.33 74.53L76.01 78.99L85.78 66.74L78.39 54.39L89.75 45.34L100.14 55.29L114.26 48.49L112.96 34.16L127.12 30.93L132.17 44.40L147.83 44.40L152.88 30.93L167.04 34.16L165.74 48.49L179.86 55.29L190.25 45.34L201.61 54.39L194.22 66.74L203.99 78.99L217.67 74.53L223.97 87.62L211.96 95.54Z"/>
<circle class="hub" cx="140" cy="120" r="16"/>
<circle class="mark" cx="140" cy="70" r="7"/>
</g>
<g class="spin-b">
<path class="gear" d="M381.60 127.83L395.07 132.88L391.84 147.04L377.51 145.74L370.71 159.86L380.66 170.25L371.61 181.61L359.26 174.22L347.01 183.99L351.47 197.67L338.38 203.97L330.46 191.96L315.19 195.44L313.26 209.71L298.74 209.71L296.81 195.44L281.54 191.96L273.62 203.97L260.53 197.67L264.99 183.99L252.74 174.22L240.39 181.61L231.34 170.25L241.29 159.86L234.49 145.74L220.16 147.04L216.93 132.88L230.40 127.83L230.40 112.17L216.93 107.12L220.16 92.96L234.49 94.26L241.29 80.14L231.34 69.75L240.39 58.39L252.74 65.78L264.99 56.01L260.53 42.33L273.62 36.03L281.54 48.04L296.81 44.56L298.74 30.29L313.26 30.29L315.19 44.56L330.46 48.04L338.38 36.03L351.47 42.33L347.01 56.01L359.26 65.78L371.61 58.39L380.66 69.75L370.71 80.14L377.51 94.26L391.84 92.96L395.07 107.12L381.60 112.17Z"/>
<circle class="hub" cx="306" cy="120" r="16"/>
<circle class="mark" cx="306" cy="70" r="7"/>
</g>
</svg>
</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。区画を抜けると、歯車は止まった位置に残ります。</p>
</section>
</div>
</main>
<footer class="dv-end">END — 41 スクロール回転</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>