03破片発散 — クリック地点から複数の破片がそれぞれ異なる角度の値で散ってから消えるボタン

<main class="stage">
<div class="ctacfb is-demo" id="ctacfb">
  <div class="ctacfb__panel">
    <div class="ctacfb__wrap">
      <canvas class="ctacfb__canvas" id="ctacfbCanvas" width="220" height="120"></canvas>
      <button class="ctacfb__btn" id="ctacfbBtn" type="button">購入完了</button>
    </div>
    <span class="ctacfb__hint">クリックすると破片が四方に散ります</span>
  </div>
</div>
</main>

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

// 계산 겹(중력·감쇠·회전)은 JS 캔버스에 있다 — 여기는 정적 배치만.
@include stage($stage-orange);

.stage { position: relative; }

.ctacfb__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  padding: $sp-5;
  border-radius: $r-card;
  background: $stage-paper;
}

.ctacfb__wrap {
  position: relative;
  width: 220px;
  height: 120px;
  display: grid;
  place-items: center;
}

.ctacfb__canvas {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.ctacfb__btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: $r-control;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-family: inherit;
  font-weight: 700;
  font-size: 15px;
  padding: $sp-3 $sp-5;
  cursor: pointer;
}

.ctacfb__hint {
  color: rgba($subject-ink, .72);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .ctacfb__panel { padding: $sp-4; gap: $sp-2; }
  .ctacfb__wrap { width: 180px; height: 100px; }
  .ctacfb__btn { padding: $sp-2 $sp-4; font-size: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  .ctacfb__btn { transition: none !important; }
}

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);
}

.stage {
  position: relative;
}

.ctacfb__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 20px;
  border-radius: 16px;
  background: #ffffff;
}

.ctacfb__wrap {
  position: relative;
  width: 220px;
  height: 120px;
  display: grid;
  place-items: center;
}

.ctacfb__canvas {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.ctacfb__btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: 12px;
  background: #0a4fe8;
  color: #fff7e6;
  font-family: inherit;
  font-weight: 700;
  font-size: 15px;
  padding: 12px 20px;
  cursor: pointer;
}

.ctacfb__hint {
  color: rgba(23, 20, 26, 0.72);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .ctacfb__panel {
    padding: 16px;
    gap: 8px;
  }
  .ctacfb__wrap {
    width: 180px;
    height: 100px;
  }
  .ctacfb__btn {
    padding: 8px 16px;
    font-size: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ctacfb__btn {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('ctacfb');
  var btn = document.getElementById('ctacfbBtn');
  var canvas = document.getElementById('ctacfbCanvas');
  var ctx = canvas.getContext('2d');
  var COLORS = ['#5b8cf8', '#ff9ebb', '#4cd4a6', '#b9a0ff'];

  // 계산 겹: 조각마다 각도·속도 값을 난수로 부여하고, 매 프레임 중력(GRAVITY)을 속도에
  // 더하고 속도에 감쇠(DRAG)를 곱해 궤적을 계산한다. 회전 값도 각자 다른 속도로 누적하고
  // 투명도 값은 남은 수명 비율로 계산해 사라진다.
  var GRAVITY = 420, DRAG = 0.985, LIFE = 900;
  var particles = [];
  var raf = null, lastT = 0;

  function burst() {
    var cx = canvas.width / 2, cy = canvas.height * 0.35;
    particles = [];
    for (var i = 0; i < 18; i++) {
      var angle = (Math.PI * 2 * i) / 18 + (Math.random() - 0.5) * 0.5;
      var speed = 90 + Math.random() * 110;
      particles.push({
        x: cx, y: cy,
        vx: Math.cos(angle) * speed,
        vy: Math.sin(angle) * speed - 60,
        rot: Math.random() * Math.PI,
        vrot: (Math.random() - 0.5) * 10,
        color: COLORS[i % COLORS.length],
        age: 0
      });
    }
    if (!raf) { lastT = performance.now(); raf = requestAnimationFrame(tick); }
  }

  function tick(now) {
    var dt = Math.min((now - lastT) / 1000, 0.05);
    lastT = now;
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    var alive = false;
    for (var i = 0; i < particles.length; i++) {
      var p = particles[i];
      p.age += dt * 1000;
      if (p.age >= LIFE) { continue; }
      alive = true;
      p.vy += GRAVITY * dt;
      p.vx *= DRAG; p.vy *= DRAG;
      p.x += p.vx * dt; p.y += p.vy * dt;
      p.rot += p.vrot * dt;
      var op = Math.max(0, 1 - p.age / LIFE);
      ctx.save();
      ctx.globalAlpha = op;
      ctx.translate(p.x, p.y);
      ctx.rotate(p.rot);
      ctx.fillStyle = p.color;
      ctx.fillRect(-4, -3, 8, 6);
      ctx.restore();
    }
    if (alive) {
      raf = requestAnimationFrame(tick);
    } else {
      raf = null;
    }
  }

  function wireReal() {
    btn.addEventListener('click', function () { root.classList.remove('is-demo'); stopAutoplay(); burst(); });
  }
  wireReal();

  var autoplayTimer = null;
  function stopAutoplay() { if (autoplayTimer) { clearInterval(autoplayTimer); autoplayTimer = null; } }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) { autoplayTimer = setInterval(burst, 1100); }
})();

import { useEffect, useRef } from "react";
import styles from "./CtaBtnConfettiBurst.module.scss";

type Particle = {
  x: number; y: number; vx: number; vy: number;
  rot: number; vrot: number; color: string; age: number;
};

export type CtaBtnConfettiBurstProps = {
  color?: string;
};

export default function CtaBtnConfettiBurst({
  color = "#0a4fe8",
}: CtaBtnConfettiBurstProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const btn = root.querySelector<HTMLButtonElement>(`.${styles.btn}`);
    const canvas = root.querySelector<HTMLCanvasElement>(`.${styles.canvas}`);
    if (!btn || !canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    const COLORS = ["#5b8cf8", "#ff9ebb", "#4cd4a6", "#b9a0ff"];

    // 계산 겹: 조각마다 각도·속도 값을 난수로 부여하고, 매 프레임 중력(GRAVITY)을 속도에
    // 더하고 속도에 감쇠(DRAG)를 곱해 궤적을 계산한다. 회전 값도 각자 다른 속도로 누적하고
    // 투명도 값은 남은 수명 비율로 계산해 사라진다.
    const GRAVITY = 420, DRAG = 0.985, LIFE = 900;
    let particles: Particle[] = [];
    let raf: number | null = null;
    let lastT = 0;

    function burst() {
      const cx = canvas!.width / 2, cy = canvas!.height * 0.35;
      particles = [];
      for (let i = 0; i < 18; i++) {
        const angle = (Math.PI * 2 * i) / 18 + (Math.random() - 0.5) * 0.5;
        const speed = 90 + Math.random() * 110;
        particles.push({
          x: cx, y: cy,
          vx: Math.cos(angle) * speed,
          vy: Math.sin(angle) * speed - 60,
          rot: Math.random() * Math.PI,
          vrot: (Math.random() - 0.5) * 10,
          color: COLORS[i % COLORS.length],
          age: 0,
        });
      }
      if (raf === null) { lastT = performance.now(); raf = requestAnimationFrame(tick); }
    }

    function tick(now: number) {
      const dt = Math.min((now - lastT) / 1000, 0.05);
      lastT = now;
      ctx!.clearRect(0, 0, canvas!.width, canvas!.height);
      let alive = false;
      for (const p of particles) {
        p.age += dt * 1000;
        if (p.age >= LIFE) continue;
        alive = true;
        p.vy += GRAVITY * dt;
        p.vx *= DRAG; p.vy *= DRAG;
        p.x += p.vx * dt; p.y += p.vy * dt;
        p.rot += p.vrot * dt;
        const op = Math.max(0, 1 - p.age / LIFE);
        ctx!.save();
        ctx!.globalAlpha = op;
        ctx!.translate(p.x, p.y);
        ctx!.rotate(p.rot);
        ctx!.fillStyle = p.color;
        ctx!.fillRect(-4, -3, 8, 6);
        ctx!.restore();
      }
      raf = alive ? requestAnimationFrame(tick) : null;
    }

    function onClick() { stopAutoplay(); burst(); }
    btn.addEventListener("click", onClick);

    let autoplayTimer: number | null = null;
    function stopAutoplay() { if (autoplayTimer !== null) { window.clearInterval(autoplayTimer); autoplayTimer = null; } }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoplayTimer = window.setInterval(burst, 1100); }

    return () => {
      stopAutoplay();
      if (raf !== null) { cancelAnimationFrame(raf); }
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.panel}>
        <div className={styles.wrap}>
          <canvas className={styles.canvas} width={220} height={120} />
          <button className={styles.btn} type="button" style={{ background: color }}>구매 완료</button>
        </div>
        <span className={styles.hint}>클릭하면 조각이 사방으로 흩어집니다</span>
      </div>
    </div>
  );
}