07Button Whose Grid Pattern Shifts With Every Tilt Value

<main class="stage">
<div class="gp is-demo" id="gp">
  <p class="gp__hint"><span>The same coordinates are multiplied by two different factors, so the inner and outer grids shift at different speeds</span></p>
  <div class="gp__scene" id="scene">
    <button class="gp__btn" id="btn" type="button" aria-label="View collection — button whose two grid layers drift apart in parallax">
      <span class="gp__grid gp__grid--far" id="gridFar" aria-hidden="true"></span>
      <span class="gp__grid gp__grid--near" id="gridNear" aria-hidden="true"></span>
      <span class="gp__label">View collection</span>
    </button>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-orange);

.gp {
  display: grid;
  gap: $sp-4;
  justify-items: center;
}

.gp__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: $subject-ink;
}

.gp__scene {
  perspective: 640px;
  padding: $sp-6;
}

.gp__btn {
  position: relative;
  border: 1px solid rgba($subject-ink, .14);
  cursor: pointer;
  padding: $sp-4 $sp-8;
  border-radius: $r-control;
  background: rgba(255, 247, 230, .82);
  color: $subject-ink;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: $shadow-raised;
  overflow: hidden;
  will-change: transform;
}

.gp__btn:focus-visible {
  outline: 2px solid $subject-ink;
  outline-offset: 3px;
}

.gp__grid {
  position: absolute;
  inset: -30%;
  pointer-events: none;
  background-repeat: repeat;
  background-size: 18px 18px;
}

.gp__grid--far {
  background-image: radial-gradient(rgba(23, 20, 26, .1) 1px, transparent 1px);
  opacity: .5;
}

.gp__grid--near {
  background-image: radial-gradient(rgba(23, 20, 26, .18) 1.4px, transparent 1.4px);
  background-size: 12px 12px;
}

.gp__label {
  position: relative;
  z-index: 1;
}

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

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);
}

.gp {
  display: grid;
  gap: 16px;
  justify-items: center;
}

.gp__hint {
  margin: 0;
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
  max-width: 260px;
  color: #17141a;
}

.gp__scene {
  perspective: 640px;
  padding: 24px;
}

.gp__btn {
  position: relative;
  border: 1px solid rgba(23, 20, 26, 0.14);
  cursor: pointer;
  padding: 16px 32px;
  border-radius: 12px;
  background: rgba(255, 247, 230, 0.82);
  color: #17141a;
  font-size: 16px;
  font-weight: 700;
  transform-style: preserve-3d;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  will-change: transform;
}

.gp__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.gp__grid {
  position: absolute;
  inset: -30%;
  pointer-events: none;
  background-repeat: repeat;
  background-size: 18px 18px;
}

.gp__grid--far {
  background-image: radial-gradient(rgba(23, 20, 26, 0.1) 1px, transparent 1px);
  opacity: 0.5;
}

.gp__grid--near {
  background-image: radial-gradient(rgba(23, 20, 26, 0.18) 1.4px, transparent 1.4px);
  background-size: 12px 12px;
}

.gp__label {
  position: relative;
  z-index: 1;
}

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

(function () {
  var root = document.getElementById('gp');
  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var gridFar = document.getElementById('gridFar');
  var gridNear = document.getElementById('gridNear');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var MAX_DEG = 9;
  var LERP = 0.16;
  var FAR_DEPTH = 10;
  var NEAR_DEPTH = 26;
  var targetNX = 0, targetNY = 0, curNX = 0, curNY = 0;
  var hasPointer = false;

  function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
  function syntheticTarget(t) { return [Math.sin(t * 0.9), Math.sin(t * 1.4 + 1.6)]; }

  function render(nx, ny) {
    btn.style.transform = 'rotateX(' + (-ny * MAX_DEG).toFixed(2) + 'deg) rotateY(' + (nx * MAX_DEG).toFixed(2) + 'deg)';
    gridFar.style.backgroundPosition = (nx * FAR_DEPTH).toFixed(1) + 'px ' + (ny * FAR_DEPTH).toFixed(1) + 'px';
    gridNear.style.backgroundPosition = (-nx * NEAR_DEPTH).toFixed(1) + 'px ' + (-ny * NEAR_DEPTH).toFixed(1) + 'px';
  }

  var t0 = null;
  function loop(now) {
    if (t0 === null) t0 = now;
    var t = (now - t0) / 1000;
    if (!hasPointer && !reduce) {
      var s = syntheticTarget(t);
      targetNX = s[0]; targetNY = s[1];
    }
    curNX += (targetNX - curNX) * LERP;
    curNY += (targetNY - curNY) * LERP;
    render(curNX, curNY);
    requestAnimationFrame(loop);
  }

  function pointFromEvent(e) {
    var r = scene.getBoundingClientRect();
    var nx = ((e.clientX - r.left) / r.width) * 2 - 1;
    var ny = ((e.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  scene.addEventListener('pointermove', function (e) {
    hasPointer = true;
    root.classList.remove('is-demo');
    var p = pointFromEvent(e);
    targetNX = p[0]; targetNY = p[1];
  });
  scene.addEventListener('pointerleave', function () {
    hasPointer = false;
    targetNX = 0; targetNY = 0;
  });
  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = -0.85; targetNY = -0.4;
    if (reduce) { render(targetNX, targetNY); }
    setTimeout(function () { if (!hasPointer) { targetNX = 0; targetNY = 0; if (reduce) { render(targetNX, targetNY); } } }, 240);
  });
  btn.addEventListener('keydown', function (e) {
    var step = 0.24;
    var moves = { ArrowLeft: [-step, 0], ArrowRight: [step, 0], ArrowUp: [0, -step], ArrowDown: [0, step] };
    var m = moves[e.key];
    if (!m) return;
    e.preventDefault();
    root.classList.remove('is-demo');
    hasPointer = true;
    targetNX = clamp(targetNX + m[0], -1, 1);
    targetNY = clamp(targetNY + m[1], -1, 1);
    if (reduce) { render(targetNX, targetNY); }
  });

  if (reduce) {
    render(0.4, -0.3);
  } else {
    requestAnimationFrame(loop);
  }
})();

// GridParallaxButton — vanilla 판(run/393/demo/07-pointer-tilt-3d-grid-parallax/index.html) 의 React 포트.
// 같은 정규화 좌표를 두 격자 층에 서로 다른 배수·부호로 곱해 배경 위치를 옮긴다 — 두 층이
// 다른 속도로 어긋나며 시차(parallax) 깊이를 만든다. 값·수치는 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { PointerEvent as ReactPointerEvent } from "react";
import styles from "./GridParallaxButton.module.scss";

type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };

const MAX_DEG = 9;
const LERP = 0.16;
const FAR_DEPTH = 10;
const NEAR_DEPTH = 26;
const LABEL = "컬렉션 보기 — 격자 두 겹이 시차로 어긋나는 버튼";

function clamp(v: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, v));
}
function syntheticTarget(t: number): [number, number] {
  return [Math.sin(t * 0.9), Math.sin(t * 1.4 + 1.6)];
}

export default function GridParallaxButton() {
  const sceneRef = useRef<HTMLDivElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);
  const gridFarRef = useRef<HTMLSpanElement | null>(null);
  const gridNearRef = useRef<HTMLSpanElement | null>(null);
  const targetXRef = useRef<number>(0) as Box<number>;
  const targetYRef = useRef<number>(0) as Box<number>;
  const curXRef = useRef<number>(0) as Box<number>;
  const curYRef = useRef<number>(0) as Box<number>;
  const hasPointerRef = useRef<boolean>(false) as Box<boolean>;
  const frameRef = useRef<number>(0) as Box<number>;
  const t0Ref = useRef<number>(0) as Box<number>;
  const [demo, setDemo] = useState(true);
  const [reduce, setReduce] = useState(false);

  function render(nx: number, ny: number): void {
    const btn = btnRef.current;
    const gridFar = gridFarRef.current;
    const gridNear = gridNearRef.current;
    if (!btn || !gridFar || !gridNear) return;
    btn.style.transform = "rotateX(" + (-ny * MAX_DEG).toFixed(2) + "deg) rotateY(" + (nx * MAX_DEG).toFixed(2) + "deg)";
    gridFar.style.backgroundPosition = (nx * FAR_DEPTH).toFixed(1) + "px " + (ny * FAR_DEPTH).toFixed(1) + "px";
    gridNear.style.backgroundPosition = (-nx * NEAR_DEPTH).toFixed(1) + "px " + (-ny * NEAR_DEPTH).toFixed(1) + "px";
  }

  useEffect(() => {
    setReduce(window.matchMedia("(prefers-reduced-motion: reduce)").matches);
  }, []);

  useEffect(() => {
    if (reduce) {
      render(0.4, -0.3);
      return;
    }
    function loop(now: number): void {
      if (t0Ref.current === 0) t0Ref.current = now;
      const t = (now - t0Ref.current) / 1000;
      if (!hasPointerRef.current) {
        const s = syntheticTarget(t);
        targetXRef.current = s[0];
        targetYRef.current = s[1];
      }
      curXRef.current += (targetXRef.current - curXRef.current) * LERP;
      curYRef.current += (targetYRef.current - curYRef.current) * LERP;
      render(curXRef.current, curYRef.current);
      frameRef.current = requestAnimationFrame(loop);
    }
    frameRef.current = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(frameRef.current);
  }, [reduce]);

  function pointFromEvent(event: ReactPointerEvent<HTMLDivElement>): [number, number] {
    const scene = sceneRef.current;
    if (!scene) return [0, 0];
    const r = scene.getBoundingClientRect();
    const nx = ((event.clientX - r.left) / r.width) * 2 - 1;
    const ny = ((event.clientY - r.top) / r.height) * 2 - 1;
    return [clamp(nx, -1, 1), clamp(ny, -1, 1)];
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    hasPointerRef.current = true;
    setDemo(false);
    const p = pointFromEvent(event);
    targetXRef.current = p[0];
    targetYRef.current = p[1];
  }

  function onPointerLeave(): void {
    hasPointerRef.current = false;
    targetXRef.current = 0;
    targetYRef.current = 0;
  }

  function onClick(): void {
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = -0.85;
    targetYRef.current = -0.4;
    if (reduce) render(targetXRef.current, targetYRef.current);
    window.setTimeout(() => {
      if (!hasPointerRef.current) {
        targetXRef.current = 0;
        targetYRef.current = 0;
        if (reduce) render(targetXRef.current, targetYRef.current);
      }
    }, 240);
  }

  function onKeyDown(event: KeyEvt): void {
    const step = 0.24;
    const moves: { [key: string]: [number, number] } = {
      ArrowLeft: [-step, 0],
      ArrowRight: [step, 0],
      ArrowUp: [0, -step],
      ArrowDown: [0, step],
    };
    const m = moves[event.key];
    if (!m) return;
    event.preventDefault();
    setDemo(false);
    hasPointerRef.current = true;
    targetXRef.current = clamp(targetXRef.current + m[0], -1, 1);
    targetYRef.current = clamp(targetYRef.current + m[1], -1, 1);
    if (reduce) render(targetXRef.current, targetYRef.current);
  }

  const cls = [styles.gp, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls}>
        <p className={styles.hint}>
          <span>같은 좌표를 배수 둘로 곱해 안쪽 격자와 바깥 격자가 서로 다른 속도로 어긋납니다</span>
        </p>
        <div className={styles.scene} ref={sceneRef} onPointerMove={onPointerMove} onPointerLeave={onPointerLeave}>
          <button className={styles.btn} ref={btnRef} type="button" aria-label={LABEL} onClick={onClick} onKeyDown={onKeyDown}>
            <span className={`${styles.grid} ${styles.gridFar}`} ref={gridFarRef} aria-hidden="true" />
            <span className={`${styles.grid} ${styles.gridNear}`} ref={gridNearRef} aria-hidden="true" />
            <span className={styles.label}>컬렉션 보기</span>
          </button>
        </div>
      </div>
    </main>
  );
}