06Coverflow

<main class="stage">
  <ul class="flow is-demo">
    <li class="flow__card" style="--i: 0;" aria-label="Bìa album"></li>
    <li class="flow__card" style="--i: 1;" aria-label="Bìa album"></li>
    <li class="flow__card" style="--i: 2;" aria-label="Bìa album"></li>
    <li class="flow__card" style="--i: 3;" aria-label="Bìa album"></li>
    <li class="flow__card" style="--i: 4;" aria-label="Bìa album"></li>
  </ul>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-loop;                                   // 카드 5장이 한 바퀴 흐르는 시간
$easing: $ease-out;
$color: $subject-cream;                                 // 카드 배경

@include stage($stage-orange);

.flow {
  position: relative;
  width: 92px;
  height: 92px;
  list-style: none;
  margin: 0;
  padding: 0;
  perspective: 640px;
}
.flow__card {
  position: absolute;
  inset: 0;
  border-radius: $r-control;
  background: $color;
  box-shadow: $shadow-press;
  // CSS 만으로 5장을 다른 위치에서 출발시킨다 — JS 없이 같은 keyframes 를 음수 delay 로 어긋나게 돈다
  animation: flow $duration $easing infinite;
  animation-delay: calc(var(--i) * -0.4s);
}

// 슬롯 5개(뒤 → 왼쪽 → 가운데 → 오른쪽 → 뒤)를 한 바퀴로. 100% 가 0% 와 같아 이음새 없이 돈다
@keyframes flow {
  0%   { transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(.6); opacity: .5; z-index: 1; }
  20%  { transform: translateX(-68px) translateZ(-40px) rotateY(35deg) scale(.82); opacity: .85; z-index: 2; }
  40%  { transform: translateX(0) translateZ(0) rotateY(0deg) scale(1); opacity: 1; z-index: 3; }
  60%  { transform: translateX(68px) translateZ(-40px) rotateY(-35deg) scale(.82); opacity: .85; z-index: 2; }
  80%  { transform: translateX(130px) translateZ(-90px) rotateY(-45deg) scale(.6); opacity: .5; z-index: 1; }
  100% { transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(.6); opacity: .5; z-index: 1; }
}

// ── 접근성: 움직임 줄이기 설정이면 다섯 장을 가운데로 모아 고정 ────────
@media (prefers-reduced-motion: reduce) {
  .flow__card { animation: none; transform: translateX(0) translateZ(0) rotateY(0deg) scale(1); opacity: 1; }
}

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);
}

.flow {
  position: relative;
  width: 92px;
  height: 92px;
  list-style: none;
  margin: 0;
  padding: 0;
  perspective: 640px;
}

.flow__card {
  position: absolute;
  inset: 0;
  border-radius: 12px;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  animation: flow 2s ease-out infinite;
  animation-delay: calc(var(--i) * -0.4s);
}

@keyframes flow {
  0% {
    transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
  20% {
    transform: translateX(-68px) translateZ(-40px) rotateY(35deg) scale(0.82);
    opacity: 0.85;
    z-index: 2;
  }
  40% {
    transform: translateX(0) translateZ(0) rotateY(0deg) scale(1);
    opacity: 1;
    z-index: 3;
  }
  60% {
    transform: translateX(68px) translateZ(-40px) rotateY(-35deg) scale(0.82);
    opacity: 0.85;
    z-index: 2;
  }
  80% {
    transform: translateX(130px) translateZ(-90px) rotateY(-45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
  100% {
    transform: translateX(-130px) translateZ(-90px) rotateY(45deg) scale(0.6);
    opacity: 0.5;
    z-index: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .flow__card {
    animation: none;
    transform: translateX(0) translateZ(0) rotateY(0deg) scale(1);
    opacity: 1;
  }
}

import type { CSSProperties } from "react";
import styles from "./Coverflow.module.scss";

export type CoverflowProps = {
  /** 카드 5장이 한 바퀴 흐르는 시간 (기본 2000ms) */
  duration?: number;
  easing?: string;
  /** 카드 배경 */
  color?: string;
  count?: number;
};

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

// JS 없이 같은 keyframes 를 음수 animation-delay 로 어긋나게 돌려 흐름을 만든다
export default function Coverflow({
  duration = 2000,
  easing = "ease-out",
  color = "#fff7e6",
  count = 5,
}: CoverflowProps) {
  const base: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <ul className={styles.flow}>
      {Array.from({ length: count }, (_, i) => (
        <li key={i} className={styles.card} style={{ ...base, "--i": i } as Vars} aria-label="앨범 커버" />
      ))}
    </ul>
  );
}