09Cursor spotlight background

<main class="stage">
  <span class="spot is-demo" aria-hidden="true"></span>
  <p class="hint">Accent light</p>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;                                // 스포트라이트가 궤도를 한 바퀴 도는 시간
$easing: $ease-spring;
$color: $subject-blue;                                // 스포트라이트 색

// ── 데모 무대 ──────────────────────────────────────────
@include stage($stage-ink);

.stage {
  position: relative;
  overflow: hidden;
}

// 작은 블러 원 하나만 transform: translate 로 궤도를 그린다. 실제 페이지에서는 같은 좌표가 pointermove 에서 온다
.spot {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 120px;
  height: 120px;
  margin: -60px 0 0 -60px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba($color, .55), transparent 70%);
  filter: blur(6px);
  pointer-events: none;
}

.spot.is-demo { animation: orbit $duration $easing infinite; }

@keyframes orbit {
  0%   { transform: translate(-90px, -40px); }
  25%  { transform: translate(90px, -50px); }
  50%  { transform: translate(70px, 60px); }
  75%  { transform: translate(-80px, 55px); }
  100% { transform: translate(-90px, -40px); }
}

.hint {
  position: relative;
  margin: 0;
  padding: 10px 20px;
  border-radius: $r-pill;
  background: rgba($stage-paper, .12);
  color: $stage-paper;
  font: 700 clamp(14px, 4vw, 18px)/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .spot.is-demo { animation: none; transform: translate(-90px, -40px); }
}

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);
}

.stage {
  position: relative;
  overflow: hidden;
}

.spot {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 120px;
  height: 120px;
  margin: -60px 0 0 -60px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(47, 109, 246, 0.55), transparent 70%);
  filter: blur(6px);
  pointer-events: none;
}

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

@keyframes orbit {
  0% {
    transform: translate(-90px, -40px);
  }
  25% {
    transform: translate(90px, -50px);
  }
  50% {
    transform: translate(70px, 60px);
  }
  75% {
    transform: translate(-80px, 55px);
  }
  100% {
    transform: translate(-90px, -40px);
  }
}
.hint {
  position: relative;
  margin: 0;
  padding: 10px 20px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.12);
  color: #ffffff;
  font: 700 clamp(14px, 4vw, 18px)/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .spot.is-demo {
    animation: none;
    transform: translate(-90px, -40px);
  }
}

// 실제 페이지에서는 좌표를 pointermove 값으로 바꿔 스포트라이트가 커서를 따라가게 한다. 데모(.is-demo)는 궤도를 자동으로 돈다.
if (matchMedia('(pointer: fine)').matches) {
  var stage = document.querySelector('.stage');
  var spot = document.querySelector('.spot');
  stage.addEventListener('pointermove', function (e) {
    var r = stage.getBoundingClientRect();
    spot.classList.remove('is-demo');
    spot.style.transform = 'translate(' + (e.clientX - r.left - r.width / 2) + 'px,' + (e.clientY - r.top - r.height / 2) + 'px)';
  });
}

import { useCallback, useState } from "react";
import type { CSSProperties, PointerEvent, ReactNode } from "react";
import styles from "./SpotlightCursorBg.module.scss";

export type SpotlightCursorBgProps = {
  children?: ReactNode;
  /** 궤도를 한 바퀴 도는 시간 (기본 2000ms) */
  duration?: number;
  easing?: string;
  /** 스포트라이트 색 */
  color?: string;
  className?: string;
};

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

export default function SpotlightCursorBg({
  children,
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
  className = "",
}: SpotlightCursorBgProps) {
  const [demo, setDemo] = useState(true);
  const [pos, setPos] = useState({ x: -90, y: -40 });

  const move = useCallback((e: PointerEvent<HTMLDivElement>) => {
    const r = e.currentTarget.getBoundingClientRect();
    setDemo(false);
    setPos({ x: e.clientX - r.left - r.width / 2, y: e.clientY - r.top - r.height / 2 });
  }, []);

  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  const t = demo ? undefined : { transform: `translate(${pos.x}px,${pos.y}px)` };

  return (
    <div className={`${styles.stage} ${className}`} style={vars} onPointerMove={move}>
      <span className={demo ? `${styles.spot} ${styles.isDemo}` : styles.spot} style={t} aria-hidden="true" />
      {children}
    </div>
  );
}