09見出しの後ろに敷くメッシュのヒーロー

<main class="stage">
<div class="mg is-demo" id="mgRoot">
  <canvas class="mg__canvas" id="mgCanvas" width="160" height="100" tabindex="0" aria-label="動くメッシュと粒子、縁の暗がりを重ねて見出しの後ろに敷き、文字の下の色が変わっても読みやすい明るさの差が保たれるかを一場面で見る。"></canvas>
  <div class="mg__hero">
    <h1 class="mg__title">やわらかな色が流れる最初の画面</h1>
    <p class="mg__sub">後ろでメッシュが動き続けても読めるかを見る</p>
  </div>
  <p class="mg__status" id="mgStatus" aria-live="polite">デモ実行中</p>
  <button class="mg__btn" id="mgBtn" type="button">一時停止</button>
  <p class="mg__caption">動くメッシュと粒子、縁の暗がりを重ねて見出しの後ろに敷き、文字の下の色が変わっても読みやすい明るさの差が保たれるかを一場面で見る。</p>
</div>
</main>

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

.mg {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  aspect-ratio: 480 / 300;
  margin: 0 auto;
  border-radius: $r-card;
  overflow: hidden;
  box-shadow: $shadow-raised;
  background: $subject-cream;
}

.mg__canvas {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
}

.mg__canvas:focus-visible {
  outline: 2px solid rgba(23, 20, 26, .85);
  outline-offset: -6px;
}

.mg__status {
  position: absolute;
  left: $sp-3;
  top: $sp-3;
  max-width: 70%;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.4;
  pointer-events: none;
}

.mg__btn {
  position: absolute;
  right: $sp-3;
  bottom: $sp-3;
  margin: 0;
  padding: $sp-1 $sp-3;
  border: 0;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font: inherit;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  cursor: pointer;
}

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

.mg__caption {
  position: absolute;
  left: $sp-3;
  bottom: $sp-3;
  max-width: 68%;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

.mg__hero {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  gap: $sp-2;
  padding: $sp-4;
  text-align: center;
  pointer-events: none;
}

.mg__title {
  margin: 0;
  color: $subject-ink;
  font-weight: 700;
  font-size: clamp(16px, 4.6vw, 28px);
  line-height: 1.3;
  text-shadow: 0 0 12px rgba(255, 255, 255, .6);
}

.mg__sub {
  margin: 0;
  color: $subject-ink;
  font-weight: 500;
  font-size: clamp(11px, 2.4vw, 14px);
  line-height: 1.5;
  text-shadow: 0 0 10px rgba(255, 255, 255, .6);
}

@media (max-width: 340px) {
  .mg__caption, .mg__btn { font-size: 10px; padding: $sp-1 $sp-2; }
  .mg__status { font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .mg { cursor: default; }
}

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);
}

.mg {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  aspect-ratio: 480/300;
  margin: 0 auto;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: #fff7e6;
}

.mg__canvas {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
}

.mg__canvas:focus-visible {
  outline: 2px solid rgba(23, 20, 26, 0.85);
  outline-offset: -6px;
}

.mg__status {
  position: absolute;
  left: 12px;
  top: 12px;
  max-width: 70%;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.4;
  pointer-events: none;
}

.mg__btn {
  position: absolute;
  right: 12px;
  bottom: 12px;
  margin: 0;
  padding: 4px 12px;
  border: 0;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font: inherit;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  cursor: pointer;
}

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

.mg__caption {
  position: absolute;
  left: 12px;
  bottom: 12px;
  max-width: 68%;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

.mg__hero {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  gap: 8px;
  padding: 16px;
  text-align: center;
  pointer-events: none;
}

.mg__title {
  margin: 0;
  color: #17141a;
  font-weight: 700;
  font-size: clamp(16px, 4.6vw, 28px);
  line-height: 1.3;
  text-shadow: 0 0 12px rgba(255, 255, 255, 0.6);
}

.mg__sub {
  margin: 0;
  color: #17141a;
  font-weight: 500;
  font-size: clamp(11px, 2.4vw, 14px);
  line-height: 1.5;
  text-shadow: 0 0 10px rgba(255, 255, 255, 0.6);
}

@media (max-width: 340px) {
  .mg__caption, .mg__btn {
    font-size: 10px;
    padding: 4px 8px;
  }
  .mg__status {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .mg {
    cursor: default;
  }
}

(function () {
  var root = document.getElementById('mgRoot');
  var canvas = document.getElementById('mgCanvas');
  var statusEl = document.getElementById('mgStatus');
  var btnEl = document.getElementById('mgBtn');
  function main(root, canvas, statusEl, btnEl) {
      var ctx0 = canvas.getContext('2d');
      if (!ctx0) {
          return function () { return; };
      }
      var ctx = ctx0;
      var CALC_W = 160, CALC_H = 100;
      var FIXED_DT = 16;
      var REDUCE_STEP_MS = 900;
      var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
      if (reduce)
          root.classList.remove('is-demo');
      var paused = false;
      var elapsed = 0, rafId = 0;
      var cleaners = [];
      function listen(target, type, fn) {
          target.addEventListener(type, fn);
          cleaners.push(function () { target.removeEventListener(type, fn); });
      }
      function clamp(v, lo, hi) { return v < lo ? lo : (v > hi ? hi : v); }
      function lerp(a, b, k) { return a + (b - a) * k; }
      function smooth(x) { var c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
      function setStatus(msg) { statusEl.textContent = msg; }
      // 시드 고정 난수 (mulberry32) — 같은 시드는 언제나 같은 수열이다
      function seedRand(seed) {
          var s = seed >>> 0;
          return function () {
              s = (s + 0x6D2B79F5) >>> 0;
              var z = s;
              z = Math.imul(z ^ (z >>> 15), z | 1);
              z ^= z + Math.imul(z ^ (z >>> 7), z | 61);
              return ((z ^ (z >>> 14)) >>> 0) / 4294967296;
          };
      }
      // 파스텔 여섯 색 — 분홍·라일락·하늘·민트·살구·버터
      var PAL = [[255, 152, 178], [182, 152, 255], [122, 200, 255], [122, 222, 186], [255, 196, 140], [255, 228, 130]];
      // 색 목록을 원형으로 읽는다. pos 의 정수부는 몇 번째 색, 소수부는 다음 색으로 넘어가는 정도
      function pick(pal, pos, out) {
          var n = pal.length;
          var i0 = Math.floor(pos);
          var f = pos - i0;
          var a = pal[((i0 % n) + n) % n];
          var b = pal[(((i0 + 1) % n) + n) % n];
          out[0] = lerp(a[0], b[0], f);
          out[1] = lerp(a[1], b[1], f);
          out[2] = lerp(a[2], b[2], f);
      }
      function put(d, x, y, r, g, b) {
          var o = (y * CALC_W + x) * 4;
          d[o] = r;
          d[o + 1] = g;
          d[o + 2] = b;
          d[o + 3] = 255;
      }
      canvas.width = CALC_W;
      canvas.height = CALC_H;
      var img = ctx.createImageData(CALC_W, CALC_H);
      var px = img.data;
      // 09 제목 뒤 히어로 — 역거리 메쉬 + 시드 고정 알갱이 + 가장자리 어둠. 글자 쪽(가운데)은 밝게 둔다
      var REDUCE_MS = 1000;
      var POWER = 2;
      var VIGNETTE = 0.22;
      var GRAIN_AMOUNT = 5;
      var ASPECT = CALC_W / CALC_H;
      var SEED_FX = [0.23, 0.34, 0.29, 0.41, 0.31];
      var SEED_FY = [0.3, 0.26, 0.37, 0.28, 0.35];
      var SEED_PH = [0.0, 0.21, 0.43, 0.62, 0.81];
      var HERO_PAL = [PAL[1], PAL[2], PAL[0], PAL[3], PAL[5]];
      var dotX = [0, 0, 0, 0, 0];
      var dotY = [0, 0, 0, 0, 0];
      var NOISE_N = CALC_W * CALC_H;
      var noiseTab = [];
      var rnd = seedRand(99);
      for (var ni = 0; ni < NOISE_N; ni += 1) {
          noiseTab.push(rnd());
      }
      function paint(t, d) {
          for (var k = 0; k < 5; k += 1) {
              dotX[k] = (0.5 + 0.42 * Math.sin(6.2832 * (t * SEED_FX[k] + SEED_PH[k]))) * ASPECT;
              dotY[k] = 0.5 + 0.4 * Math.cos(6.2832 * (t * SEED_FY[k] + SEED_PH[k] * 1.6));
          }
          var halfP = POWER / 2;
          var frame = Math.floor(t * 30);
          for (var y = 0; y < CALC_H; y += 1) {
              var v = y / (CALC_H - 1);
              for (var x = 0; x < CALC_W; x += 1) {
                  var u = (x / (CALC_W - 1)) * ASPECT;
                  var wr = 0, wg = 0, wb = 0, ws = 0;
                  for (var j = 0; j < 5; j += 1) {
                      var dx = u - dotX[j], dy = v - dotY[j];
                      var w = 1 / (Math.pow(dx * dx + dy * dy, halfP) + 0.003);
                      wr += w * HERO_PAL[j][0];
                      wg += w * HERO_PAL[j][1];
                      wb += w * HERO_PAL[j][2];
                      ws += w;
                  }
                  // 가장자리 어둠 — 중심에서 멀수록 곱하는 값이 1 에서 1 - VIGNETTE 로 내려간다
                  var ex = (x / (CALC_W - 1) - 0.5) * 2, ey = (y / (CALC_H - 1) - 0.5) * 2;
                  var vig = 1 - VIGNETTE * smooth((Math.sqrt(ex * ex * 0.6 + ey * ey) - 0.55) / 0.9);
                  var grain = (noiseTab[(y * CALC_W + x + frame * 991) % NOISE_N] - 0.5) * GRAIN_AMOUNT;
                  put(d, x, y, clamp((wr / ws) * vig + grain, 0, 255), clamp((wg / ws) * vig + grain, 0, 255), clamp((wb / ws) * vig + grain, 0, 255));
              }
          }
      }
      function draw() {
          paint(elapsed / 1000, px);
          ctx.putImageData(img, 0, 0);
      }
      var lastTs = null;
      var accMs = 0;
      function tick(ts) {
          if (lastTs === null) {
              lastTs = ts;
          }
          var frameDt = Math.min(ts - lastTs, 48);
          lastTs = ts;
          if (!paused) {
              accMs += frameDt;
              while (accMs >= FIXED_DT) {
                  elapsed += FIXED_DT;
                  accMs -= FIXED_DT;
              }
              draw();
          }
          rafId = requestAnimationFrame(tick);
      }
      function onButton() {
          root.classList.remove('is-demo');
          if (reduce) {
              elapsed += REDUCE_STEP_MS;
              draw();
              setStatus('一場面ずつ送っています');
              return;
          }
          paused = !paused;
          btnEl.textContent = paused ? '再生' : '一時停止';
          setStatus(paused ? '一時停止中' : 'デモ実行中');
      }
      draw();
      listen(btnEl, 'click', function () { onButton(); });
      listen(canvas, 'pointerdown', function () { onButton(); });
      listen(canvas, 'keydown', function (e) {
          var k = e.key;
          if (k === 'Enter' || k === ' ') {
              e.preventDefault();
              onButton();
          }
      });
      if (reduce) {
          elapsed = REDUCE_MS;
          draw();
          btnEl.textContent = '次の場面';
          setStatus('一場面ずつ送っています');
      }
      else {
          rafId = requestAnimationFrame(tick);
      }
      function destroy() {
          cancelAnimationFrame(rafId);
          for (var i = 0; i < cleaners.length; i += 1) {
              cleaners[i]();
          }
      }
      return destroy;
  }
  main(root, canvas, statusEl, btnEl);
})();

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

function main(root: HTMLDivElement, canvas: HTMLCanvasElement, statusEl: HTMLElement, btnEl: HTMLButtonElement): () => void {
  var ctx0 = canvas.getContext('2d');
  if (!ctx0) { return function (): void { return; }; }
  var ctx: CanvasRenderingContext2D = ctx0;
  var CALC_W = 160, CALC_H = 100;
  var FIXED_DT = 16;
  var REDUCE_STEP_MS = 900;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) root.classList.remove('is-demo');
  var paused = false;
  var elapsed = 0, rafId = 0;
  var cleaners: Array<() => void> = [];

  function listen(target: EventTarget, type: string, fn: (e: Event) => void): void {
    target.addEventListener(type, fn);
    cleaners.push(function (): void { target.removeEventListener(type, fn); });
  }
  function clamp(v: number, lo: number, hi: number): number { return v < lo ? lo : (v > hi ? hi : v); }
  function lerp(a: number, b: number, k: number): number { return a + (b - a) * k; }
  function smooth(x: number): number { var c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
  function setStatus(msg: string): void { statusEl.textContent = msg; }
  // 시드 고정 난수 (mulberry32) — 같은 시드는 언제나 같은 수열이다
  function seedRand(seed: number): () => number {
    var s = seed >>> 0;
    return function (): number {
      s = (s + 0x6D2B79F5) >>> 0;
      var z = s;
      z = Math.imul(z ^ (z >>> 15), z | 1);
      z ^= z + Math.imul(z ^ (z >>> 7), z | 61);
      return ((z ^ (z >>> 14)) >>> 0) / 4294967296;
    };
  }
  // 파스텔 여섯 색 — 분홍·라일락·하늘·민트·살구·버터
  var PAL: number[][] = [[255, 152, 178], [182, 152, 255], [122, 200, 255], [122, 222, 186], [255, 196, 140], [255, 228, 130]];
  // 색 목록을 원형으로 읽는다. pos 의 정수부는 몇 번째 색, 소수부는 다음 색으로 넘어가는 정도
  function pick(pal: number[][], pos: number, out: number[]): void {
    var n = pal.length;
    var i0 = Math.floor(pos);
    var f = pos - i0;
    var a = pal[((i0 % n) + n) % n];
    var b = pal[(((i0 + 1) % n) + n) % n];
    out[0] = lerp(a[0], b[0], f);
    out[1] = lerp(a[1], b[1], f);
    out[2] = lerp(a[2], b[2], f);
  }
  function put(d: Uint8ClampedArray, x: number, y: number, r: number, g: number, b: number): void {
    var o = (y * CALC_W + x) * 4;
    d[o] = r;
    d[o + 1] = g;
    d[o + 2] = b;
    d[o + 3] = 255;
  }

  canvas.width = CALC_W;
  canvas.height = CALC_H;
  var img = ctx.createImageData(CALC_W, CALC_H);
  var px = img.data;

  // 09 제목 뒤 히어로 — 역거리 메쉬 + 시드 고정 알갱이 + 가장자리 어둠. 글자 쪽(가운데)은 밝게 둔다
  var REDUCE_MS = 1000;
  var POWER = 2;
  var VIGNETTE = 0.22;
  var GRAIN_AMOUNT = 5;
  var ASPECT = CALC_W / CALC_H;
  var SEED_FX = [0.23, 0.34, 0.29, 0.41, 0.31];
  var SEED_FY = [0.3, 0.26, 0.37, 0.28, 0.35];
  var SEED_PH = [0.0, 0.21, 0.43, 0.62, 0.81];
  var HERO_PAL: number[][] = [PAL[1], PAL[2], PAL[0], PAL[3], PAL[5]];
  var dotX: number[] = [0, 0, 0, 0, 0];
  var dotY: number[] = [0, 0, 0, 0, 0];
  var NOISE_N = CALC_W * CALC_H;
  var noiseTab: number[] = [];
  var rnd = seedRand(99);
  for (var ni = 0; ni < NOISE_N; ni += 1) { noiseTab.push(rnd()); }
  function paint(t: number, d: Uint8ClampedArray): void {
    for (var k = 0; k < 5; k += 1) {
      dotX[k] = (0.5 + 0.42 * Math.sin(6.2832 * (t * SEED_FX[k] + SEED_PH[k]))) * ASPECT;
      dotY[k] = 0.5 + 0.4 * Math.cos(6.2832 * (t * SEED_FY[k] + SEED_PH[k] * 1.6));
    }
    var halfP = POWER / 2;
    var frame = Math.floor(t * 30);
    for (var y = 0; y < CALC_H; y += 1) {
      var v = y / (CALC_H - 1);
      for (var x = 0; x < CALC_W; x += 1) {
        var u = (x / (CALC_W - 1)) * ASPECT;
        var wr = 0, wg = 0, wb = 0, ws = 0;
        for (var j = 0; j < 5; j += 1) {
          var dx = u - dotX[j], dy = v - dotY[j];
          var w = 1 / (Math.pow(dx * dx + dy * dy, halfP) + 0.003);
          wr += w * HERO_PAL[j][0];
          wg += w * HERO_PAL[j][1];
          wb += w * HERO_PAL[j][2];
          ws += w;
        }
        // 가장자리 어둠 — 중심에서 멀수록 곱하는 값이 1 에서 1 - VIGNETTE 로 내려간다
        var ex = (x / (CALC_W - 1) - 0.5) * 2, ey = (y / (CALC_H - 1) - 0.5) * 2;
        var vig = 1 - VIGNETTE * smooth((Math.sqrt(ex * ex * 0.6 + ey * ey) - 0.55) / 0.9);
        var grain = (noiseTab[(y * CALC_W + x + frame * 991) % NOISE_N] - 0.5) * GRAIN_AMOUNT;
        put(d, x, y,
          clamp((wr / ws) * vig + grain, 0, 255),
          clamp((wg / ws) * vig + grain, 0, 255),
          clamp((wb / ws) * vig + grain, 0, 255));
      }
    }
  }

  function draw(): void {
    paint(elapsed / 1000, px);
    ctx.putImageData(img, 0, 0);
  }
  var lastTs: number | null = null;
  var accMs = 0;
  function tick(ts: number): void {
    if (lastTs === null) { lastTs = ts; }
    var frameDt = Math.min(ts - lastTs, 48);
    lastTs = ts;
    if (!paused) {
      accMs += frameDt;
      while (accMs >= FIXED_DT) {
        elapsed += FIXED_DT;
        accMs -= FIXED_DT;
      }
      draw();
    }
    rafId = requestAnimationFrame(tick);
  }
  function onButton(): void {
    root.classList.remove('is-demo');
    if (reduce) {
      elapsed += REDUCE_STEP_MS;
      draw();
      setStatus('한 장면씩 넘기는 중');
      return;
    }
    paused = !paused;
    btnEl.textContent = paused ? '재생' : '멈춤';
    setStatus(paused ? '일시정지됨' : '시연 중');
  }
  draw();
  listen(btnEl, 'click', function (): void { onButton(); });
  listen(canvas, 'pointerdown', function (): void { onButton(); });
  listen(canvas, 'keydown', function (e: Event): void {
    var k = (e as KeyboardEvent).key;
    if (k === 'Enter' || k === ' ') { e.preventDefault(); onButton(); }
  });
  if (reduce) {
    elapsed = REDUCE_MS;
    draw();
    btnEl.textContent = '다음 장면';
    setStatus('한 장면씩 넘기는 중');
  } else {
    rafId = requestAnimationFrame(tick);
  }

  function destroy(): void {
    cancelAnimationFrame(rafId);
    for (var i = 0; i < cleaners.length; i += 1) { cleaners[i](); }
  }
  return destroy;
}

export default function MgHeroBackdropVignetteScene() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const canvasRef = useRef<HTMLCanvasElement | null>(null);
  const statusRef = useRef<HTMLParagraphElement | null>(null);
  const btnRef = useRef<HTMLButtonElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const statusEl = statusRef.current;
    const btnEl = btnRef.current;
    if (!root || !canvas || !statusEl || !btnEl) return;
    return main(root, canvas, statusEl, btnEl);
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.mg} is-demo`} ref={rootRef}>
        <canvas className={styles.mg__canvas} ref={canvasRef} width={160} height={100} tabIndex={0} aria-label="움직이는 메쉬와 알갱이, 가장자리 어둠을 합쳐 제목 뒤에 깔고, 글자 밑의 색이 바뀌어도 읽기 쉬운 밝기 차가 유지되는지 한 장면으로 본다." />
        <div className={styles.mg__hero}>
          <h1 className={styles.mg__title}>부드러운 색이 흐르는 첫 화면</h1>
          <p className={styles.mg__sub}>글자 뒤에서 메쉬가 계속 움직여도 읽히는지 본다</p>
        </div>
        <p className={styles.mg__status} ref={statusRef} aria-live="polite">시연 중</p>
        <button className={styles.mg__btn} ref={btnRef} type="button">멈춤</button>
        <p className={styles.mg__caption}>움직이는 메쉬와 알갱이, 가장자리 어둠을 합쳐 제목 뒤에 깔고, 글자 밑의 색이 바뀌어도 읽기 쉬운 밝기 차가 유지되는지 한 장면으로 본다.</p>
      </div>
    </main>
  );
}