03프레임 시퀀스 스크럽

<main class="stage">
  <div class="sp is-demo">
    <div class="sp__scroller">
      <div class="sp__pad">
        <div class="sp__pin">
          <div class="sp__window">
            <div class="sp__strip" aria-hidden="true">
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
              <div class="sp__frame"><span class="sp__item"></span><span class="sp__lid"></span><span class="sp__box"></span></div>
            </div>
          </div>
          <p class="sp__hint">스크롤한 만큼 컷이 넘어갑니다</p>
        </div>
      </div>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 1s;          // alternate 라 한 바퀴(앞으로 갔다 뒤로)는 2s
$easing: linear;        // 스크럽은 등속이라야 스크롤 양과 컷 번호가 1:1
$color: $subject-cream;

@include stage($stage-orange);

.sp {
  --h: clamp(148px, 58vh, 176px);
  --frame: 168px;
  width: min(360px, 92vw);
}

// ⚠ 타임라인에 이름을 붙인다. scroll(nearest) 는 창의 overflow: hidden 까지 스크롤 컨테이너로 쳐서
// 띠가 **절대 안 움직이는** 타임라인에 묶인다 (실측)
.sp__scroller {
  height: var(--h);
  overflow-y: auto;
  scroll-timeline-name: --sp-scroll;
  scroll-timeline-axis: block;
  scrollbar-width: none;
  &::-webkit-scrollbar { display: none; }
}

// ⚠ 여기는 padding-bottom 이 아니라 height 다. sticky 가 붙어 있을 수 있는 범위는 부모의
// **콘텐츠 박스**라, padding 으로만 늘린 자리는 안 쳐준다 — 창이 곧바로 위로 흘러나간다 (실측)
.sp__pad { height: calc(var(--h) * 2.2); }

.sp__pin {
  position: sticky;
  top: 0;
  display: grid;
  justify-items: center;
  gap: $sp-2;
}

// 창은 한 컷만 보여준다. 실제로 움직이는 건 안쪽 띠뿐이다
.sp__window {
  width: var(--frame);
  height: 104px;
  overflow: hidden;
  border-radius: $r-card;
  background: rgba(23, 20, 26, .78);
}

// ── 실제 동작: 스크롤 진행이 컷 번호가 된다.
//    steps(8, jump-none) 은 0 과 1 을 모두 포함해 여덟 컷이 정확히 한 번씩 선다 ──
.sp__strip {
  display: flex;
  width: max-content;
  animation-name: sp-scrub;
  animation-duration: 1s;
  animation-timing-function: steps(8, jump-none);
  animation-fill-mode: both;
  animation-timeline: --sp-scroll;
}

@keyframes sp-scrub {
  from { transform: translateX(0); }
  to   { transform: translateX(-87.5%); }
}

// 컷마다 overflow: hidden — 열린 뚜껑이 옆 컷 자리로 넘어가면 창 하나에 두 컷이 겹쳐 보인다
.sp__frame {
  position: relative;
  flex: 0 0 var(--frame);
  width: var(--frame);
  height: 104px;
  overflow: hidden;
}
.sp__frame:nth-child(1) { --i: 0; }
.sp__frame:nth-child(2) { --i: 1; }
.sp__frame:nth-child(3) { --i: 2; }
.sp__frame:nth-child(4) { --i: 3; }
.sp__frame:nth-child(5) { --i: 4; }
.sp__frame:nth-child(6) { --i: 5; }
.sp__frame:nth-child(7) { --i: 6; }
.sp__frame:nth-child(8) { --i: 7; }

.sp__box {
  position: absolute;
  left: 40px;
  bottom: 20px;
  width: 88px;
  height: 40px;
  border-radius: $r-sm;
  background: $color;
}

// 뚜껑은 컷마다 14도씩 더 열린다 — 애니메이션이 아니라 컷의 생김새 그 자체
.sp__lid {
  position: absolute;
  left: 40px;
  bottom: 60px;
  width: 88px;
  height: 12px;
  border-radius: $r-xs;
  background: $stage-yellow;
  transform-origin: left bottom; // 규칙8: 뚜껑 모서리 경첩
  transform: rotate(calc(var(--i) * -14deg));
}

.sp__item {
  position: absolute;
  left: 72px;
  bottom: 48px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: $subject-mint;
  opacity: calc(var(--i) / 7);
  transform: translateY(calc(var(--i) * -6px));
}

.sp__hint {
  margin: 0;
  color: $subject-ink;   // 주황 무대 위 크림 2.83:1 → 잉크 5.50:1
  font-size: 12px;
  line-height: 16px;
  font-weight: 700;
}

// ── 격자 미리보기 루프 — 같은 띠를 시간으로 민다(앞으로 갔다 되감기) ──
.sp.is-demo .sp__strip {
  animation-duration: $duration;
  animation-timing-function: steps(8, jump-none);
  animation-direction: alternate;
  animation-iteration-count: infinite;
  animation-timeline: auto;
}

// 한 컷 = 12.5% — 여섯 번째 컷에서 멈춘다
@media (prefers-reduced-motion: reduce) {
  .sp__strip { animation: none !important; transform: translateX(-62.5%); }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.sp {
  --h: clamp(148px, 58vh, 176px);
  --frame: 168px;
  width: min(360px, 92vw);
}

.sp__scroller {
  height: var(--h);
  overflow-y: auto;
  scroll-timeline-name: --sp-scroll;
  scroll-timeline-axis: block;
  scrollbar-width: none;
}
.sp__scroller::-webkit-scrollbar {
  display: none;
}

.sp__pad {
  height: calc(var(--h) * 2.2);
}

.sp__pin {
  position: sticky;
  top: 0;
  display: grid;
  justify-items: center;
  gap: 8px;
}

.sp__window {
  width: var(--frame);
  height: 104px;
  overflow: hidden;
  border-radius: 16px;
  background: rgba(23, 20, 26, 0.78);
}

.sp__strip {
  display: flex;
  width: max-content;
  animation-name: sp-scrub;
  animation-duration: 1s;
  animation-timing-function: steps(8, jump-none);
  animation-fill-mode: both;
  animation-timeline: --sp-scroll;
}

@keyframes sp-scrub {
  from {
    transform: translateX(0);
  }
  to {
    transform: translateX(-87.5%);
  }
}
.sp__frame {
  position: relative;
  flex: 0 0 var(--frame);
  width: var(--frame);
  height: 104px;
  overflow: hidden;
}

.sp__frame:nth-child(1) {
  --i: 0;
}

.sp__frame:nth-child(2) {
  --i: 1;
}

.sp__frame:nth-child(3) {
  --i: 2;
}

.sp__frame:nth-child(4) {
  --i: 3;
}

.sp__frame:nth-child(5) {
  --i: 4;
}

.sp__frame:nth-child(6) {
  --i: 5;
}

.sp__frame:nth-child(7) {
  --i: 6;
}

.sp__frame:nth-child(8) {
  --i: 7;
}

.sp__box {
  position: absolute;
  left: 40px;
  bottom: 20px;
  width: 88px;
  height: 40px;
  border-radius: 8px;
  background: #fff7e6;
}

.sp__lid {
  position: absolute;
  left: 40px;
  bottom: 60px;
  width: 88px;
  height: 12px;
  border-radius: 4px;
  background: #ffd23f;
  transform-origin: left bottom;
  transform: rotate(calc(var(--i) * -14deg));
}

.sp__item {
  position: absolute;
  left: 72px;
  bottom: 48px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #4cd4a6;
  opacity: calc(var(--i) / 7);
  transform: translateY(calc(var(--i) * -6px));
}

.sp__hint {
  margin: 0;
  color: #17141a;
  font-size: 12px;
  line-height: 16px;
  font-weight: 700;
}

.sp.is-demo .sp__strip {
  animation-duration: 1s;
  animation-timing-function: steps(8, jump-none);
  animation-direction: alternate;
  animation-iteration-count: infinite;
  animation-timeline: auto;
}

@media (prefers-reduced-motion: reduce) {
  .sp__strip {
    animation: none !important;
    transform: translateX(-62.5%);
  }
}

// 실제 동작은 CSS 만: 띠를 미는 건 animation-timeline: scroll() 이고 timing 은 steps(8, jump-none).
var r = document.querySelector('.sp');
var s = r.querySelector('.sp__scroller');
function stopDemo(){ r.classList.remove('is-demo'); }
r.addEventListener('pointerdown', stopDemo);
s.addEventListener('scroll', stopDemo, { passive: true });

import type { CSSProperties, ReactNode } from "react";
import styles from "./FrameSequenceScrub.module.scss";

export type FrameSequenceScrubProps = {
  frames?: number;
  hint?: string;
  preview?: boolean;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type FrameVars = CSSProperties & { "--i"?: number };

export default function FrameSequenceScrub({
  frames = 8,
  hint = "Each bit of scroll advances one frame.",
  preview = true,
  duration = 1000,
  easing = "linear",
  color = "#fff7e6",
}: FrameSequenceScrubProps): ReactNode {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  const cls = preview ? `${styles.sp} ${styles.isDemo}` : styles.sp;
  const list: number[] = [];
  for (let i = 0; i < frames; i += 1) list.push(i);

  return (
    <div className={cls} style={vars}>
      <div className={styles.scroller}>
        <div className={styles.pad}>
          <div className={styles.pin}>
            <div className={styles.window}>
              <div className={styles.strip} aria-hidden="true">
                {list.map((i: number): ReactNode => {
                  const fv: FrameVars = { "--i": i };
                  return (
                    <div className={styles.frame} style={fv} key={i}>
                      <span className={styles.item} />
                      <span className={styles.lid} />
                      <span className={styles.box} />
                    </div>
                  );
                })}
              </div>
            </div>
            <p className={styles.hint}>{hint}</p>
          </div>
        </div>
      </div>
    </div>
  );
}