05A fancy particle mouse — DOM confetti

<main class="stage">
<div class="pb is-demo" id="pb">
  <div class="pb__field" role="img" aria-label="A white ring moves the cursor and colorful shards burst behind it">
    <span class="pb__cursor" id="pbCursor" aria-hidden="true"></span>
    <span class="pb__p pb__p--dot" aria-hidden="true"></span>
    <span class="pb__p pb__p--ring" aria-hidden="true"></span>
    <span class="pb__p pb__p--dot" aria-hidden="true"></span>
    <span class="pb__p pb__p--gem" aria-hidden="true"></span>
    <span class="pb__p pb__p--dot" aria-hidden="true"></span>
    <span class="pb__p pb__p--ring" aria-hidden="true"></span>
    <span class="pb__p pb__p--gem" aria-hidden="true"></span>
    <span class="pb__p pb__p--dot" aria-hidden="true"></span>
  </div>
  <p class="pb__hint">Move the mouse faster and more shards burst</p>
</div>
</main>

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

// 화려한 파티클 마우스 — 캔버스 없이 span 파편을 pool 로 돌려 쓴다.
// 실제 조작은 커서 이동 거리를 쌓아 26px마다 파편 하나를 Element.animate(WAAPI)로 터뜨린다.
// 격자 미리보기(.is-demo)는 커서 고리가 좌우로 지나가고 파편 여덟이 그 자리에서 흩어지는 루프다.

$duration: $dur-loop;
$easing: $ease-out;
$color: $subject-cream;

@include stage($stage-ink);

.pb { display: grid; justify-items: center; gap: $sp-3; width: 100%; }

.pb__field {
  position: relative; overflow: hidden;
  width: 100%; height: clamp(110px, 32vh, 160px);
  border: 3px solid $color; border-radius: $r-card;
}

.pb__cursor {
  position: absolute; left: 0; top: 0;
  width: 16px; height: 16px; box-sizing: border-box;
  border: 3px solid $color; border-radius: 50%;
  will-change: transform;
}

// 파편 세 모양 — 점·고리·마름모 (아이콘이 아니라 기하 도형이다). 색은 --pc 로 받는다
.pb__p {
  position: absolute; left: 0; top: 0;
  width: 10px; height: 10px;
  opacity: 0;
  will-change: transform, opacity;
}
.pb__p--dot { background: var(--pc, $subject-pink); border-radius: 50%; }
.pb__p--ring {
  box-sizing: border-box;
  background: transparent; border: 3px solid var(--pc, $subject-mint); border-radius: 50%;
}
.pb__p--gem { background: var(--pc, $subject-lilac); transform: rotate(45deg); }

.pb__hint { margin: 0; color: $color; font-weight: 700; font-size: clamp(9px, 2.4vw, 11px); }

// ── 미리보기 루프: 커서 고리가 왼쪽 → 오른쪽으로 지나가고, 파편이 그 뒤에서 흩어진다
.pb.is-demo .pb__cursor { animation: pbCursor $duration $ease-spring infinite; }
.pb.is-demo .pb__p      { animation: pbFly $duration $easing infinite; }

@keyframes pbCursor {
  0%, 4%   { transform: translate3d(24px, 56px, 0); }
  46%, 52% { transform: translate3d(236px, 42px, 0); }
  88%, 100% { transform: translate3d(24px, 56px, 0); }
}

// 파편마다 시작점(키프레임 안 px)과 delay 를 달리해 한 번에 쏟아지지 않게 한다
.pb.is-demo .pb__p:nth-child(2) { animation-delay: 0ms;    animation-name: pbA; }
.pb.is-demo .pb__p:nth-child(3) { animation-delay: 90ms;   animation-name: pbB; }
.pb.is-demo .pb__p:nth-child(4) { animation-delay: 180ms;  animation-name: pbC; }
.pb.is-demo .pb__p:nth-child(5) { animation-delay: 250ms;  animation-name: pbD; }
.pb.is-demo .pb__p:nth-child(6) { animation-delay: 1000ms; animation-name: pbE; }
.pb.is-demo .pb__p:nth-child(7) { animation-delay: 1090ms; animation-name: pbF; }
.pb.is-demo .pb__p:nth-child(8) { animation-delay: 1170ms; animation-name: pbG; }
.pb.is-demo .pb__p:nth-child(9) { animation-delay: 1250ms; animation-name: pbH; }

@keyframes pbA {
  0%   { transform: translate3d(60px, 56px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(96px, 20px, 0) rotate(160deg) scale(.15); opacity: 0; }
}
@keyframes pbB {
  0%   { transform: translate3d(100px, 48px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(140px, 92px, 0) rotate(200deg) scale(.15); opacity: 0; }
}
@keyframes pbC {
  0%   { transform: translate3d(140px, 54px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(176px, 18px, 0) rotate(140deg) scale(.15); opacity: 0; }
}
@keyframes pbD {
  0%   { transform: translate3d(180px, 46px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(214px, 86px, 0) rotate(220deg) scale(.15); opacity: 0; }
}
@keyframes pbE {
  0%   { transform: translate3d(220px, 46px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(186px, 90px, 0) rotate(180deg) scale(.15); opacity: 0; }
}
@keyframes pbF {
  0%   { transform: translate3d(180px, 52px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(146px, 14px, 0) rotate(210deg) scale(.15); opacity: 0; }
}
@keyframes pbG {
  0%   { transform: translate3d(120px, 50px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(84px, 94px, 0) rotate(150deg) scale(.15); opacity: 0; }
}
@keyframes pbH {
  0%   { transform: translate3d(76px, 52px, 0) rotate(0deg) scale(1); opacity: 1; }
  62%, 100% { transform: translate3d(40px, 16px, 0) rotate(190deg) scale(.15); opacity: 0; }
}

@media (max-width: 340px) {
  .pb { gap: $sp-2; }
  .pb__field { height: clamp(96px, 28vh, 130px); }
  .pb__p { width: 8px; height: 8px; }
  .pb__p--ring { border-width: 2px; }
}

@media (prefers-reduced-motion: reduce) {
  .pb.is-demo .pb__cursor,
  .pb.is-demo .pb__p { animation: none !important; }
  // reduce 에서는 파편이 바닥에 흩어진 정물로 남고 커서 고리만 가운데 있다
  .pb.is-demo .pb__cursor { transform: translate3d(120px, 48px, 0) !important; }
  .pb.is-demo .pb__p:nth-child(2) { transform: translate3d(60px, 84px, 0) rotate(20deg) scale(1) !important; opacity: 1 !important; }
  .pb.is-demo .pb__p:nth-child(4) { transform: translate3d(112px, 92px, 0) rotate(-14deg) scale(1) !important; opacity: 1 !important; }
  .pb.is-demo .pb__p:nth-child(6) { transform: translate3d(164px, 88px, 0) rotate(30deg) scale(1) !important; opacity: 1 !important; }
  .pb.is-demo .pb__p:nth-child(8) { transform: translate3d(206px, 84px, 0) rotate(-24deg) scale(1) !important; opacity: 1 !important; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pb {
  display: grid;
  justify-items: center;
  gap: 12px;
  width: 100%;
}

.pb__field {
  position: relative;
  overflow: hidden;
  width: 100%;
  height: clamp(110px, 32vh, 160px);
  border: 3px solid #fff7e6;
  border-radius: 16px;
}

.pb__cursor {
  position: absolute;
  left: 0;
  top: 0;
  width: 16px;
  height: 16px;
  box-sizing: border-box;
  border: 3px solid #fff7e6;
  border-radius: 50%;
  will-change: transform;
}

.pb__p {
  position: absolute;
  left: 0;
  top: 0;
  width: 10px;
  height: 10px;
  opacity: 0;
  will-change: transform, opacity;
}

.pb__p--dot {
  background: var(--pc, #ff9ebb);
  border-radius: 50%;
}

.pb__p--ring {
  box-sizing: border-box;
  background: transparent;
  border: 3px solid var(--pc, #4cd4a6);
  border-radius: 50%;
}

.pb__p--gem {
  background: var(--pc, #b9a0ff);
  transform: rotate(45deg);
}

.pb__hint {
  margin: 0;
  color: #fff7e6;
  font-weight: 700;
  font-size: clamp(9px, 2.4vw, 11px);
}

.pb.is-demo .pb__cursor {
  animation: pbCursor 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.pb.is-demo .pb__p {
  animation: pbFly 2s ease-out infinite;
}

@keyframes pbCursor {
  0%, 4% {
    transform: translate3d(24px, 56px, 0);
  }
  46%, 52% {
    transform: translate3d(236px, 42px, 0);
  }
  88%, 100% {
    transform: translate3d(24px, 56px, 0);
  }
}
.pb.is-demo .pb__p:nth-child(2) {
  animation-delay: 0ms;
  animation-name: pbA;
}

.pb.is-demo .pb__p:nth-child(3) {
  animation-delay: 90ms;
  animation-name: pbB;
}

.pb.is-demo .pb__p:nth-child(4) {
  animation-delay: 180ms;
  animation-name: pbC;
}

.pb.is-demo .pb__p:nth-child(5) {
  animation-delay: 250ms;
  animation-name: pbD;
}

.pb.is-demo .pb__p:nth-child(6) {
  animation-delay: 1000ms;
  animation-name: pbE;
}

.pb.is-demo .pb__p:nth-child(7) {
  animation-delay: 1090ms;
  animation-name: pbF;
}

.pb.is-demo .pb__p:nth-child(8) {
  animation-delay: 1170ms;
  animation-name: pbG;
}

.pb.is-demo .pb__p:nth-child(9) {
  animation-delay: 1250ms;
  animation-name: pbH;
}

@keyframes pbA {
  0% {
    transform: translate3d(60px, 56px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(96px, 20px, 0) rotate(160deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbB {
  0% {
    transform: translate3d(100px, 48px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(140px, 92px, 0) rotate(200deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbC {
  0% {
    transform: translate3d(140px, 54px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(176px, 18px, 0) rotate(140deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbD {
  0% {
    transform: translate3d(180px, 46px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(214px, 86px, 0) rotate(220deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbE {
  0% {
    transform: translate3d(220px, 46px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(186px, 90px, 0) rotate(180deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbF {
  0% {
    transform: translate3d(180px, 52px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(146px, 14px, 0) rotate(210deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbG {
  0% {
    transform: translate3d(120px, 50px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(84px, 94px, 0) rotate(150deg) scale(0.15);
    opacity: 0;
  }
}
@keyframes pbH {
  0% {
    transform: translate3d(76px, 52px, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  62%, 100% {
    transform: translate3d(40px, 16px, 0) rotate(190deg) scale(0.15);
    opacity: 0;
  }
}
@media (max-width: 340px) {
  .pb {
    gap: 8px;
  }
  .pb__field {
    height: clamp(96px, 28vh, 130px);
  }
  .pb__p {
    width: 8px;
    height: 8px;
  }
  .pb__p--ring {
    border-width: 2px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pb.is-demo .pb__cursor,
  .pb.is-demo .pb__p {
    animation: none !important;
  }
  .pb.is-demo .pb__cursor {
    transform: translate3d(120px, 48px, 0) !important;
  }
  .pb.is-demo .pb__p:nth-child(2) {
    transform: translate3d(60px, 84px, 0) rotate(20deg) scale(1) !important;
    opacity: 1 !important;
  }
  .pb.is-demo .pb__p:nth-child(4) {
    transform: translate3d(112px, 92px, 0) rotate(-14deg) scale(1) !important;
    opacity: 1 !important;
  }
  .pb.is-demo .pb__p:nth-child(6) {
    transform: translate3d(164px, 88px, 0) rotate(30deg) scale(1) !important;
    opacity: 1 !important;
  }
  .pb.is-demo .pb__p:nth-child(8) {
    transform: translate3d(206px, 84px, 0) rotate(-24deg) scale(1) !important;
    opacity: 1 !important;
  }
}

var root = document.getElementById('pb');
var field = root.querySelector('.pb__field');
var cursorEl = document.getElementById('pbCursor');
var pool = Array.prototype.slice.call(root.querySelectorAll('.pb__p'));

var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
// 오래된 브라우저에서는 파편 없이 커서 고리만 움직이게 둔다 (animate 는 인스턴스 메서드다)
var canAnimate = typeof document.body.animate === 'function';

var colors = ['#ff9ebb', '#4cd4a6', '#b9a0ff', '#6ec8ff', '#ffd23f'];
var shapes = ['pb__p--dot', 'pb__p--ring', 'pb__p--gem'];

var last = null;
var travel = 0;
var next = 0;

// 커서가 이동한 거리를 쌓아 두었다가 26px마다 파편 하나를 터뜨린다 — 속도에 비례한다
function spawn(x, y, dx, dy) {
  var element = pool[next];
  next = (next + 1) % pool.length;
  element.className = 'pb__p ' + shapes[(Math.random() * shapes.length) | 0];
  // 모양마다 --pc 를 색으로 쓴다 (점은 배경, 고리는 테두리, 마름모는 배경)
  element.style.setProperty('--pc', colors[(Math.random() * colors.length) | 0]);
  var ang = Math.atan2(dy, dx) + (Math.random() - 0.5) * 2.4;
  var dist = 34 + Math.random() * 46;
  var tx = x + Math.cos(ang) * dist;
  var ty = y + Math.sin(ang) * dist;
  element.animate([
    { transform: 'translate3d(' + (x - 5) + 'px,' + (y - 5) + 'px,0) rotate(0deg) scale(1)', opacity: 1 },
    { transform: 'translate3d(' + (tx - 5) + 'px,' + (ty - 5) + 'px,0) rotate(200deg) scale(.15)', opacity: 0 }
  ], { duration: 620 + Math.random() * 320, easing: 'cubic-bezier(.2,.8,.2,1)' });
}

function place(cx, cy) {
  var r = field.getBoundingClientRect();
  var x = cx - r.left;
  var y = cy - r.top;
  cursorEl.style.transform = 'translate3d(' + (x - 8) + 'px,' + (y - 8) + 'px,0)';
  if (last) {
    var dx = x - last.x, dy = y - last.y;
    travel += Math.sqrt(dx * dx + dy * dy);
    while (travel > 26) {
      travel -= 26;
      if (!reduce && canAnimate) { spawn(x, y, dx, dy); }
    }
  }
  last = { x: x, y: y };
}

window.addEventListener('pointermove', function (e) {
  root.classList.remove('is-demo');
  place(e.clientX, e.clientY);
});
window.addEventListener('pointerdown', function (e) {
  root.classList.remove('is-demo');
  last = null;
  place(e.clientX, e.clientY);
});

// ParticleBurst — vanilla 판(run/079/demo/05-follow-particle-burst/index.html) 의 React 포트.
// 캔버스 없이 span 파편을 pool 로 돌려 쓴다. 커서 이동 거리를 쌓아 26px마다 파편 하나를
// element.animate(WAAPI)로 터뜨린다 — 색 배열·모양·거리·시간은 vanilla 와 같은 값이다.
import { useEffect, useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ParticleBurst.module.scss";

export type ParticleBurstProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
// useRef 는 T | null 을 돌려준다. 처음부터 값이 있고 절대 비지 않는 상자는 이렇게 좁혀 쓴다
type Box<T> = { current: T };
// 전역 DOM 타입에 기대지 않는다 — 포인터 이벤트에서 실제로 읽는 것만 적는다
type PtrEvt = { clientX: number; clientY: number };

const FIELD_LABEL = "커서를 흰 고리가 움직이고 그 뒤로 색색의 파편이 터지는 그림";
const HINT = "마우스를 빠르게 움직이면 파편이 더 많이 터집니다";
const POOL_SIZE = 8;
// 커서가 이동한 거리를 쌓아 두었다가 이만큼마다 파편 하나를 터뜨린다 — 속도에 비례한다
const SPAWN_EVERY = 26;
const COLORS = ["#ff9ebb", "#4cd4a6", "#b9a0ff", "#6ec8ff", "#ffd23f"];
// 파편 세 모양 — 점·고리·마름모. module.scss 의 로컬 클래스 이름과 짝이다
const SHAPES = [styles.pDot, styles.pRing, styles.pGem];

export default function ParticleBurst({
  duration = 2000,
  easing = "ease-out",
  color = "#fff7e6",
}: ParticleBurstProps) {
  const fieldRef = useRef<HTMLDivElement | null>(null) as Box<HTMLDivElement>;
  const cursorRef = useRef<HTMLSpanElement | null>(null);
  const poolRef = useRef<(HTMLSpanElement | null)[]>(new Array(POOL_SIZE).fill(null)) as Box<(HTMLSpanElement | null)[]>;
  const [demo, setDemo] = useState(true);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  function setPool(index: number) {
    return (el: HTMLSpanElement | null): void => {
      poolRef.current[index] = el;
    };
  }

  useEffect(() => {
    const field = fieldRef.current;
    if (!field) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    // 오래된 브라우저에서는 파편 없이 커서 고리만 움직이게 둔다 (animate 는 인스턴스 메서드다)
    const canAnimate = typeof document.body.animate === "function";

    let last: { x: number; y: number } | null = null;
    let travel = 0;
    let next = 0;

    function spawn(x: number, y: number, dx: number, dy: number): void {
      const element = poolRef.current[next];
      next = (next + 1) % poolRef.current.length;
      if (!element) return;
      element.className = styles.p + " " + SHAPES[(Math.random() * SHAPES.length) | 0];
      // 모양마다 --pc 를 색으로 쓴다 (점은 배경, 고리는 테두리, 마름모는 배경)
      element.style.setProperty("--pc", COLORS[(Math.random() * COLORS.length) | 0]);
      const ang = Math.atan2(dy, dx) + (Math.random() - 0.5) * 2.4;
      const dist = 34 + Math.random() * 46;
      const tx = x + Math.cos(ang) * dist;
      const ty = y + Math.sin(ang) * dist;
      element.animate(
        [
          { transform: "translate3d(" + (x - 5) + "px," + (y - 5) + "px,0) rotate(0deg) scale(1)", opacity: 1 },
          { transform: "translate3d(" + (tx - 5) + "px," + (ty - 5) + "px,0) rotate(200deg) scale(.15)", opacity: 0 },
        ],
        { duration: 620 + Math.random() * 320, easing: "cubic-bezier(.2,.8,.2,1)" }
      );
    }

    function place(cx: number, cy: number): void {
      const r = field.getBoundingClientRect();
      const x = cx - r.left;
      const y = cy - r.top;
      const cursor = cursorRef.current;
      if (cursor) cursor.style.transform = "translate3d(" + (x - 8) + "px," + (y - 8) + "px,0)";
      if (last) {
        const dx = x - last.x;
        const dy = y - last.y;
        travel += Math.sqrt(dx * dx + dy * dy);
        while (travel > SPAWN_EVERY) {
          travel -= SPAWN_EVERY;
          if (!reduce && canAnimate) {
            spawn(x, y, dx, dy);
          }
        }
      }
      last = { x: x, y: y };
    }

    function onMove(event: PtrEvt): void {
      setDemo(false);
      place(event.clientX, event.clientY);
    }
    function onDown(event: PtrEvt): void {
      setDemo(false);
      last = null;
      place(event.clientX, event.clientY);
    }

    window.addEventListener("pointermove", onMove);
    window.addEventListener("pointerdown", onDown);
    return () => {
      window.removeEventListener("pointermove", onMove);
      window.removeEventListener("pointerdown", onDown);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.root + (demo ? " " + styles.isDemo : "")} style={vars}>
        <div className={styles.field} ref={fieldRef} role="img" aria-label={FIELD_LABEL}>
          <span className={styles.cursor} aria-hidden="true" ref={cursorRef}></span>
          <span className={styles.p + " " + styles.pDot} aria-hidden="true" ref={setPool(0)}></span>
          <span className={styles.p + " " + styles.pRing} aria-hidden="true" ref={setPool(1)}></span>
          <span className={styles.p + " " + styles.pDot} aria-hidden="true" ref={setPool(2)}></span>
          <span className={styles.p + " " + styles.pGem} aria-hidden="true" ref={setPool(3)}></span>
          <span className={styles.p + " " + styles.pDot} aria-hidden="true" ref={setPool(4)}></span>
          <span className={styles.p + " " + styles.pRing} aria-hidden="true" ref={setPool(5)}></span>
          <span className={styles.p + " " + styles.pGem} aria-hidden="true" ref={setPool(6)}></span>
          <span className={styles.p + " " + styles.pDot} aria-hidden="true" ref={setPool(7)}></span>
        </div>
        <p className={styles.hint}>{HINT}</p>
      </div>
    </main>
  );
}