06Chữ gợn sóng

<main class="stage">
  <h1 class="wave" data-split>Vui lòng chờ</h1>
</main>

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

$duration: $dur-loop;                              // 한 글자가 오르내리는 한 주기
$easing: $ease-out;
$stagger: 90ms;                                    // --i 1당 시차 — 이 간격이 파도를 만든다

@include stage($stage-yellow);

.wave {
  margin: 0;
  display: flex;
  gap: clamp(2px, 1vw, 6px);
  font-weight: 800; font-size: clamp(28px, 10vw, 46px); line-height: 1; font-family: inherit;
  color: $subject-ink;

  span {
    display: inline-block;
    animation: wave-up $duration $easing infinite, letter-blur-in $duration $easing infinite;
    animation-delay: calc(var(--i) * #{$stagger} + var(--n) * 70ms);   // 노이즈로 파도가 기계적으로 안 맞게
  }
}

@keyframes wave-up {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-16px); }
}

@keyframes letter-blur-in {
  0%, 100% { filter: blur(0); }
  50%      { filter: blur(3px); }   // 정점에서 살짝 흐려져 움직임 잔상처럼 보인다
}

@media (prefers-reduced-motion: reduce) {
  .wave span { animation: none; transform: none; filter: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.wave {
  margin: 0;
  display: flex;
  gap: clamp(2px, 1vw, 6px);
  font-weight: 800;
  font-size: clamp(28px, 10vw, 46px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}
.wave span {
  display: inline-block;
  animation: wave-up 2s ease-out infinite, letter-blur-in 2s ease-out infinite;
  animation-delay: calc(var(--i) * 90ms + var(--n) * 70ms);
}

@keyframes wave-up {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-16px);
  }
}
@keyframes letter-blur-in {
  0%, 100% {
    filter: blur(0);
  }
  50% {
    filter: blur(3px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .wave span {
    animation: none;
    transform: none;
    filter: none;
  }
}

(function(){
  function splitLetters(el){
    var text = el.textContent;
    el.textContent = "";
    Array.from(text).forEach(function(ch, i){
      var span = document.createElement("span");
      span.className = "letter";
      var seed = Math.sin((i + 1) * 12.9898) * 43758.5453;
      var noise = seed - Math.floor(seed);
      span.style.setProperty("--i", i);
      span.style.setProperty("--n", noise.toFixed(3));
      span.textContent = ch === " " ? " " : ch;
      el.appendChild(span);
    });
  }
  document.querySelectorAll("[data-split]").forEach(splitLetters);
})();

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

type Vars = CSSProperties & { "--i"?: number; "--n"?: number };

function noise(i: number): number {
  const s = Math.sin((i + 1) * 12.9898) * 43758.5453;
  return Number((s - Math.floor(s)).toFixed(3));
}

export type WaveTextProps = {
  letters: string[];
  /** 글자들이 한 바퀴 도는 시간 ms (기본 2000) */
  duration?: number;
  /** --i 1당 시차 ms (기본 90ms) — 이 간격이 파도를 만든다 */
  stagger?: number;
  color?: string;
};

export default function WaveText({ letters, duration = 2000, color = "#17141a" }: WaveTextProps) {
  return (
    <h1 className={styles.wave} style={{ "--color": color, "--duration": `${duration}ms` } as CSSProperties}>
      {letters.map((ch, i) => (
        <span key={i} style={{ "--i": i, "--n": noise(i) } as Vars}>{ch}</span>
      ))}
    </h1>
  );
}