03値ノイズフィールドでマスごとの登場順を計算するディゾルブ

<main class="stage">
<div class="rv is-demo" id="rv">
  <p class="rv__hint"><span>クリックまたはEnterキーを押すと、格子のマスがノイズ値の順に散らばり次の場面を現します</span></p>
  <div class="rv__panel" id="panel" tabindex="0" role="button" aria-label="値ノイズフィールドでピクセルごとの出現順序を計算するディゾルブをもう一度再生">
    <canvas class="rv__cv" id="cv" aria-hidden="true"></canvas>
  </div>
</div>
</main>

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

// 계산 겹(리빌 판정)은 index.html 의 PRECOMPUTE()/RENDER() 에 있다. 여기는 무대·레이아웃만.
$duration: $dur-loop;
$easing:   $ease-out;
$color:    $subject-ink;

@include stage($stage-orange);

.rv {
  --img-a1: #{$stage-orange};
  --img-a2: #{$subject-cream};
  --img-b1: #{$subject-blue};
  --img-b2: #{$subject-sky};
  --accent: #{$color};
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
  width: min(400px, 92vw);
}

.rv__hint {
  margin: 0;
  color: rgba($subject-ink, .72);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.rv__panel {
  position: relative;
  width: 100%;
  height: 176px;
  border-radius: $r-card;
  overflow: hidden;
  cursor: pointer;
  box-shadow: 0 0 0 1px rgba($subject-ink, .12);
  transition: box-shadow $duration $easing;
}

.rv__panel:hover {
  box-shadow: 0 0 0 1px $color;
}

.rv__panel:focus-visible {
  outline: 2px solid $color;
  outline-offset: 2px;
}

.rv__cv {
  display: block;
  width: 100%;
  height: 100%;
}

@media (max-width: 340px) {
  .rv__hint { font-size: 11px; }
  .rv__panel, .rv__cv { height: 120px; }
}

@media (prefers-reduced-motion: reduce) {
  .rv__panel { 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);
}

.rv {
  --img-a1: #ff4d1f;
  --img-a2: #fff7e6;
  --img-b1: #2f6df6;
  --img-b2: #6ec8ff;
  --accent: #17141a;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: min(400px, 92vw);
}

.rv__hint {
  margin: 0;
  color: rgba(23, 20, 26, 0.72);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.rv__panel {
  position: relative;
  width: 100%;
  height: 176px;
  border-radius: 16px;
  overflow: hidden;
  cursor: pointer;
  box-shadow: 0 0 0 1px rgba(23, 20, 26, 0.12);
  transition: box-shadow 2s ease-out;
}

.rv__panel:hover {
  box-shadow: 0 0 0 1px #17141a;
}

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

.rv__cv {
  display: block;
  width: 100%;
  height: 100%;
}

@media (max-width: 340px) {
  .rv__hint {
    font-size: 11px;
  }
  .rv__panel, .rv__cv {
    height: 120px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .rv__panel {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('rv');
  var panel = document.getElementById('panel');
  var cv = document.getElementById('cv');
  var ctx = cv.getContext('2d');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var isDemo = true;

  // 결정론 난수 — 이 데모는 Math.random 을 쓰지 않는다. LCG(선형합동생성기) 하나로 장면을 만든다.
  function makeLcg(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }

  var css = getComputedStyle(root);
  function tok(name, fb) { var v = css.getPropertyValue(name); return v ? (v.trim() || fb) : fb; }
  var COLOR_A1 = tok('--img-a1', '#ff5a2e');
  var COLOR_A2 = tok('--img-a2', '#fff3e6');
  var COLOR_B1 = tok('--img-b1', '#2e6bff');
  var COLOR_B2 = tok('--img-b2', '#bfe4ff');

  var W = 0, H = 0, dpr = 1;
  var bufA = document.createElement('canvas');
  var bufB = document.createElement('canvas');
  var bctxA = bufA.getContext('2d');
  var bctxB = bufB.getContext('2d');

  // 장면 A(따뜻한 톤)·B(차가운 톤) — 전부 캔버스로 직접 그린다. 외부 사진·파일 0.
  function paintScene(bctx, w, h, seed, warm) {
    var rng = makeLcg(seed);
    var g = bctx.createLinearGradient(0, 0, w, h);
    if (warm) { g.addColorStop(0, COLOR_A1); g.addColorStop(1, COLOR_A2); }
    else { g.addColorStop(0, COLOR_B1); g.addColorStop(1, COLOR_B2); }
    bctx.fillStyle = g;
    bctx.fillRect(0, 0, w, h);
    bctx.globalAlpha = 0.55;
    if (warm) {
      for (var i = 0; i < 8; i++) {
        bctx.fillStyle = i % 2 ? COLOR_A2 : COLOR_A1;
        bctx.beginPath();
        bctx.arc(rng() * w, rng() * h, 12 + rng() * 30, 0, Math.PI * 2);
        bctx.fill();
      }
    } else {
      var bandW = Math.max(14, w * 0.05);
      for (var x = -h; x < w + h; x += bandW * 2) {
        bctx.fillStyle = COLOR_B2;
        bctx.beginPath();
        bctx.moveTo(x, 0); bctx.lineTo(x + bandW, 0); bctx.lineTo(x + bandW - h, h); bctx.lineTo(x - h, h);
        bctx.closePath(); bctx.fill();
      }
      for (var j = 0; j < 6; j++) {
        bctx.fillStyle = COLOR_A2;
        bctx.beginPath(); bctx.arc(rng() * w, rng() * h, 5 + rng() * 9, 0, Math.PI * 2); bctx.fill();
      }
    }
    bctx.globalAlpha = 1;
  }

  var SEED_A = 301, SEED_B = 302, SEED_NOISE = 303;
  var PLAY_MS = 950;
  var NOISE_CELL_PX = 16; // 격자 칸 크기 — 변형: 16px -> 8px(더 잘게 흩어지는 느낌)
  var NOISE_FREQ = 0.36;
  var PERM = buildPerm(SEED_NOISE);
  var cols, rows, cellNoise;

  function buildPerm(seed) {
    var rng = makeLcg(seed);
    var p = [];
    for (var i = 0; i < 256; i++) p.push(i);
    for (var i = 255; i > 0; i--) {
      var j = Math.floor(rng() * (i + 1));
      var t = p[i]; p[i] = p[j]; p[j] = t;
    }
    return p.concat(p);
  }
  function fadeN(t) { return t * t * t * (t * (t * 6 - 15) + 10); }
  function lerpN(a, b, t) { return a + (b - a) * t; }
  function gradN(hash, x, y) {
    var h = hash & 3, u = h < 2 ? x : y, v = h < 2 ? y : x;
    return ((h & 1) ? -u : u) + ((h & 2) ? -v : v);
  }
  function noise2(x, y) {
    var xi = Math.floor(x) & 255, yi = Math.floor(y) & 255;
    var xf = x - Math.floor(x), yf = y - Math.floor(y);
    var u = fadeN(xf), v = fadeN(yf);
    var aa = PERM[PERM[xi] + yi], ab = PERM[PERM[xi] + yi + 1];
    var ba = PERM[PERM[xi + 1] + yi], bb = PERM[PERM[xi + 1] + yi + 1];
    var x1 = lerpN(gradN(aa, xf, yf), gradN(ba, xf - 1, yf), u);
    var x2 = lerpN(gradN(ab, xf, yf - 1), gradN(bb, xf - 1, yf - 1), u);
    return Math.max(0, Math.min(1, (lerpN(x1, x2, v) + 1) / 2));
  }

  function PRECOMPUTE() {
    cols = Math.ceil(W / NOISE_CELL_PX);
    rows = Math.ceil(H / NOISE_CELL_PX);
    cellNoise = new Float32Array(cols * rows);
    for (var r = 0; r < rows; r++) {
      for (var c = 0; c < cols; c++) cellNoise[r * cols + c] = noise2(c * NOISE_FREQ, r * NOISE_FREQ);
    }
  }

  function RENDER(p) {
    ctx.drawImage(bufB, 0, 0, W, H);
    var cw = Math.round(NOISE_CELL_PX * dpr), ch = Math.round(NOISE_CELL_PX * dpr);
    for (var r = 0; r < rows; r++) {
      for (var c = 0; c < cols; c++) {
        if (cellNoise[r * cols + c] <= p) {
          var sx = Math.round(c * NOISE_CELL_PX * dpr), sy = Math.round(r * NOISE_CELL_PX * dpr);
          ctx.drawImage(bufA, sx, sy, cw, ch, c * NOISE_CELL_PX, r * NOISE_CELL_PX, NOISE_CELL_PX, NOISE_CELL_PX);
        }
      }
    }
  }

  function fit() {
    var r = panel.getBoundingClientRect();
    dpr = window.devicePixelRatio || 1;
    W = r.width; H = r.height;
    cv.width = Math.round(W * dpr); cv.height = Math.round(H * dpr);
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    bufA.width = bufB.width = cv.width;
    bufA.height = bufB.height = cv.height;
    bctxA.setTransform(dpr, 0, 0, dpr, 0, 0);
    bctxB.setTransform(dpr, 0, 0, dpr, 0, 0);
    paintScene(bctxA, W, H, SEED_A, true);
    paintScene(bctxB, W, H, SEED_B, false);
    PRECOMPUTE();
  }

  function human() { if (isDemo) { root.classList.remove('is-demo'); isDemo = false; } }

  var progress = 0, target = 0, playT0 = 0, playFrom = 0, playing = false;

  function easeInOut(t) { return t < 0.5 ? 2 * t * t : 1 - Math.pow(-2 * t + 2, 2) / 2; }

  function play() {
    // 실사용 경로 — 클릭·Enter·Space 로 두 장면을 다시 전환한다.
    human();
    playFrom = progress; target = progress < 0.5 ? 1 : 0;
    playT0 = 0; playing = true;
  }

  function stepPlay(now) {
    if (!playing) return;
    if (!playT0) playT0 = now;
    var t = Math.min(1, (now - playT0) / PLAY_MS);
    progress = playFrom + (target - playFrom) * easeInOut(t);
    if (t >= 1) { playing = false; progress = target; }
  }

  var DRIVE_PERIOD_MS = 2000; // 렌더 캐처 창(설정 초=2.0)과 같은 주기 — 시연 전용
  var driveStart = 0;
  function triangle(frac) { return frac < 0.5 ? frac * 2 : 2 - frac * 2; }
  function driveTick(now) {
    if (!driveStart) driveStart = now;
    if (isDemo) { // .is-demo && !reduce 경로에서만 실행된다(아래 reduce 분기)
      var frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
      progress = triangle(frac);
    }
    requestAnimationFrame(driveTick);
  }

  function frame(now) {
    stepPlay(now);
    RENDER(progress);
    requestAnimationFrame(frame);
  }

  window.addEventListener('resize', fit);
  fit();

  if (reduce) {
    // reduce — 자동 루프 없음, 계산은 그대로 둘고 즉시 전환만 허용한다.
    root.classList.add('is-still');
    progress = 0.5; RENDER(progress);
    panel.addEventListener('click', function () { human(); progress = progress < 0.5 ? 1 : 0; RENDER(progress); });
    panel.addEventListener('keydown', function (e) {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); human(); progress = progress < 0.5 ? 1 : 0; RENDER(progress); }
    });
  } else {
    panel.addEventListener('click', play);
    panel.addEventListener('keydown', function (e) {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); play(); }
    });
    requestAnimationFrame(frame);
    requestAnimationFrame(driveTick);
  }
})();

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

export default function NoiseDissolve() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const panelRef = useRef<HTMLDivElement | null>(null);
  const cvRef = useRef<HTMLCanvasElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const panel = panelRef.current;
    const cv = cvRef.current;
    if (!root || !panel || !cv) return;
    const ctx = cv.getContext("2d");
    if (!ctx) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let isDemo = true;

    // 결정론 난수 — 이 데모는 Math.random 을 쓰지 않는다. LCG(선형합동생성기) 하나로 장면·노이즈를 만든다.
    function makeLcg(seed: number) {
      let s = seed >>> 0;
      return function () {
        s = (s * 1664525 + 1013904223) >>> 0;
        return s / 4294967296;
      };
    }

    const css = getComputedStyle(root);
    function tok(name: string, fb: string) {
      const v = css.getPropertyValue(name);
      return v ? v.trim() || fb : fb;
    }
    const COLOR_A1 = tok("--img-a1", "#ff5a2e");
    const COLOR_A2 = tok("--img-a2", "#fff3e6");
    const COLOR_B1 = tok("--img-b1", "#2e6bff");
    const COLOR_B2 = tok("--img-b2", "#bfe4ff");

    let W = 0;
    let H = 0;
    let dpr = 1;
    const bufA = document.createElement("canvas");
    const bufB = document.createElement("canvas");
    const bctxA = bufA.getContext("2d");
    const bctxB = bufB.getContext("2d");
    if (!bctxA || !bctxB) return;

    // 장면 A(따뜻한 톤)·B(차가운 톤) — 전부 캔버스로 직접 그린다. 외부 사진·파일 0.
    function paintScene(bctx: CanvasRenderingContext2D, w: number, h: number, seed: number, warm: boolean) {
      const rng = makeLcg(seed);
      const g = bctx.createLinearGradient(0, 0, w, h);
      if (warm) {
        g.addColorStop(0, COLOR_A1);
        g.addColorStop(1, COLOR_A2);
      } else {
        g.addColorStop(0, COLOR_B1);
        g.addColorStop(1, COLOR_B2);
      }
      bctx.fillStyle = g;
      bctx.fillRect(0, 0, w, h);
      bctx.globalAlpha = 0.55;
      if (warm) {
        for (let i = 0; i < 8; i++) {
          bctx.fillStyle = i % 2 ? COLOR_A2 : COLOR_A1;
          bctx.beginPath();
          bctx.arc(rng() * w, rng() * h, 12 + rng() * 30, 0, Math.PI * 2);
          bctx.fill();
        }
      } else {
        const bandW = Math.max(14, w * 0.05);
        for (let x = -h; x < w + h; x += bandW * 2) {
          bctx.fillStyle = COLOR_B2;
          bctx.beginPath();
          bctx.moveTo(x, 0);
          bctx.lineTo(x + bandW, 0);
          bctx.lineTo(x + bandW - h, h);
          bctx.lineTo(x - h, h);
          bctx.closePath();
          bctx.fill();
        }
        for (let j = 0; j < 6; j++) {
          bctx.fillStyle = COLOR_A2;
          bctx.beginPath();
          bctx.arc(rng() * w, rng() * h, 5 + rng() * 9, 0, Math.PI * 2);
          bctx.fill();
        }
      }
      bctx.globalAlpha = 1;
    }

    const SEED_A = 301;
    const SEED_B = 302;
    const SEED_NOISE = 303;
    const PLAY_MS = 950;
    const NOISE_CELL_PX = 16; // 격자 칸 크기 — 변형: 16px -> 8px(더 잘게 흩어지는 느낌)
    const NOISE_FREQ = 0.36;

    function buildPerm(seed: number) {
      const rng = makeLcg(seed);
      const p: number[] = [];
      for (let i = 0; i < 256; i++) p.push(i);
      for (let i = 255; i > 0; i--) {
        const j = Math.floor(rng() * (i + 1));
        const t = p[i];
        p[i] = p[j];
        p[j] = t;
      }
      return p.concat(p);
    }
    function fadeN(t: number) {
      return t * t * t * (t * (t * 6 - 15) + 10);
    }
    function lerpN(a: number, b: number, t: number) {
      return a + (b - a) * t;
    }
    function gradN(hash: number, x: number, y: number) {
      const h = hash & 3;
      const u = h < 2 ? x : y;
      const v = h < 2 ? y : x;
      return (h & 1 ? -u : u) + (h & 2 ? -v : v);
    }
    const PERM = buildPerm(SEED_NOISE);
    function noise2(x: number, y: number) {
      const xi = Math.floor(x) & 255;
      const yi = Math.floor(y) & 255;
      const xf = x - Math.floor(x);
      const yf = y - Math.floor(y);
      const u = fadeN(xf);
      const v = fadeN(yf);
      const aa = PERM[PERM[xi] + yi];
      const ab = PERM[PERM[xi] + yi + 1];
      const ba = PERM[PERM[xi + 1] + yi];
      const bb = PERM[PERM[xi + 1] + yi + 1];
      const x1 = lerpN(gradN(aa, xf, yf), gradN(ba, xf - 1, yf), u);
      const x2 = lerpN(gradN(ab, xf, yf - 1), gradN(bb, xf - 1, yf - 1), u);
      return Math.max(0, Math.min(1, (lerpN(x1, x2, v) + 1) / 2));
    }

    let cols = 0;
    let rows = 0;
    let cellNoise: Float32Array | null = null;

    function PRECOMPUTE() {
      cols = Math.ceil(W / NOISE_CELL_PX);
      rows = Math.ceil(H / NOISE_CELL_PX);
      cellNoise = new Float32Array(cols * rows);
      for (let r = 0; r < rows; r++) {
        for (let c = 0; c < cols; c++) cellNoise[r * cols + c] = noise2(c * NOISE_FREQ, r * NOISE_FREQ);
      }
    }

    function RENDER(p: number) {
      ctx!.drawImage(bufB, 0, 0, W, H);
      const cn = cellNoise!;
      const cw = Math.round(NOISE_CELL_PX * dpr);
      const ch = Math.round(NOISE_CELL_PX * dpr);
      for (let r = 0; r < rows; r++) {
        for (let c = 0; c < cols; c++) {
          if (cn[r * cols + c] <= p) {
            const sx = Math.round(c * NOISE_CELL_PX * dpr);
            const sy = Math.round(r * NOISE_CELL_PX * dpr);
            ctx!.drawImage(bufA, sx, sy, cw, ch, c * NOISE_CELL_PX, r * NOISE_CELL_PX, NOISE_CELL_PX, NOISE_CELL_PX);
          }
        }
      }
    }

    function fit() {
      const r = panel!.getBoundingClientRect();
      dpr = window.devicePixelRatio || 1;
      W = r.width;
      H = r.height;
      cv!.width = Math.round(W * dpr);
      cv!.height = Math.round(H * dpr);
      ctx!.setTransform(dpr, 0, 0, dpr, 0, 0);
      bufA.width = bufB.width = cv!.width;
      bufA.height = bufB.height = cv!.height;
      bctxA!.setTransform(dpr, 0, 0, dpr, 0, 0);
      bctxB!.setTransform(dpr, 0, 0, dpr, 0, 0);
      paintScene(bctxA!, W, H, SEED_A, true);
      paintScene(bctxB!, W, H, SEED_B, false);
      PRECOMPUTE();
    }

    function human() {
      if (isDemo) {
        root!.classList.remove("is-demo");
        isDemo = false;
      }
    }

    let progress = 0;
    let target = 0;
    let playT0 = 0;
    let playFrom = 0;
    let playing = false;

    function easeInOut(t: number) {
      return t < 0.5 ? 2 * t * t : 1 - Math.pow(-2 * t + 2, 2) / 2;
    }

    function play() {
      // 실사용 경로 — 클릭·Enter·Space 로 두 장면을 다시 전환한다.
      human();
      playFrom = progress;
      target = progress < 0.5 ? 1 : 0;
      playT0 = 0;
      playing = true;
    }

    function stepPlay(now: number) {
      if (!playing) return;
      if (!playT0) playT0 = now;
      const t = Math.min(1, (now - playT0) / PLAY_MS);
      progress = playFrom + (target - playFrom) * easeInOut(t);
      if (t >= 1) {
        playing = false;
        progress = target;
      }
    }

    const DRIVE_PERIOD_MS = 2000; // 렌더 캐처 창(설정 초=2.0)과 같은 주기 — 시연 전용
    let driveStart = 0;
    let rafFrame = 0;
    let rafDrive = 0;

    function triangle(frac: number) {
      return frac < 0.5 ? frac * 2 : 2 - frac * 2;
    }

    function driveTick(now: number) {
      if (!driveStart) driveStart = now;
      if (isDemo) {
        // .is-demo && !reduce 경로에서만 실행된다(아래 reduce 분기)
        const frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
        progress = triangle(frac);
      }
      rafDrive = requestAnimationFrame(driveTick);
    }

    function frame(now: number) {
      stepPlay(now);
      RENDER(progress);
      rafFrame = requestAnimationFrame(frame);
    }

    function onClick() {
      play();
    }
    function onKeyDown(e: Event) {
      const ke = e as KeyboardEvent;
      if (ke.key === "Enter" || ke.key === " ") {
        ke.preventDefault();
        play();
      }
    }
    function onClickReduce() {
      human();
      progress = progress < 0.5 ? 1 : 0;
      RENDER(progress);
    }
    function onKeyDownReduce(e: Event) {
      const ke = e as KeyboardEvent;
      if (ke.key === "Enter" || ke.key === " ") {
        ke.preventDefault();
        human();
        progress = progress < 0.5 ? 1 : 0;
        RENDER(progress);
      }
    }

    window.addEventListener("resize", fit);
    fit();

    if (reduce) {
      // reduce — 자동 루프 없음, 계산은 그대로 두고 즉시 전환만 허용한다.
      root.classList.add("is-still");
      progress = 0.5;
      RENDER(progress);
      panel.addEventListener("click", onClickReduce);
      panel.addEventListener("keydown", onKeyDownReduce);
    } else {
      panel.addEventListener("click", onClick);
      panel.addEventListener("keydown", onKeyDown);
      rafFrame = requestAnimationFrame(frame);
      rafDrive = requestAnimationFrame(driveTick);
    }

    return () => {
      window.removeEventListener("resize", fit);
      cancelAnimationFrame(rafFrame);
      cancelAnimationFrame(rafDrive);
      if (reduce) {
        panel.removeEventListener("click", onClickReduce);
        panel.removeEventListener("keydown", onKeyDownReduce);
      } else {
        panel.removeEventListener("click", onClick);
        panel.removeEventListener("keydown", onKeyDown);
      }
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.root} is-demo`} ref={rootRef}>
        <p className={styles.hint}>
          <span>클릭하거나 Enter 를 누르면 격자 칸이 노이즈 값 순서로 흩어지며 다음 장면을 드러냅니다</span>
        </p>
        <div
          className={styles.panel}
          ref={panelRef}
          tabIndex={0}
          role="button"
          aria-label="값 노이즈 필드로 픽셀마다 등장 순서를 계산하는 디졸브 다시 재생"
        >
          <canvas className={styles.cv} ref={cvRef} aria-hidden="true" />
        </div>
      </div>
    </main>
  );
}