08City block — a scene where each building's height comes from the layout math

<main class="stage">
<div class="cb" id="cb">
  <p class="cb__hint">Building heights come from a seed-42 random number, and window-flicker delays from the same seeded random — so the same city appears every time</p>
  <div class="cb__field" role="img" aria-label="Scene with nine buildings of different heights, each window flickering to its own rhythm">
    <div class="cb__world" id="world"></div>
  </div>
  <p class="cb__meta">Seed  <b id="seed">42</b>  · buildings  <b id="n">9</b>buildings</p>
</div>
</main>

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

// 도시 블록 씬(08) — 무대는 페이퍼. 건물 높이(--h)·창문 개수·깜빡임 지연(--delay) 은
// mulberry32(시드 42) 로 한 번만 뽑아 고정한다. 창문 깜빡임만 진짜 @keyframes 무한
// 애니메이션으로 계속 돈다 — 나머지(위치·높이)는 정적 값이다.

$duration: $dur-loop;
$easing: $ease-out;
$color: $subject-blue;

@include stage($stage-paper);

.cb {
  display: flex; flex-direction: column; align-items: center; gap: $sp-2;
  width: 100%; max-width: 420px;
}

.cb__hint {
  margin: 0; font-weight: 700; font-size: clamp(10px, 2.6vw, 12px); line-height: 1.35;
  color: $subject-ink; text-align: center;
}

.cb__field {
  position: relative;
  width: clamp(180px, 42vw, 220px); height: clamp(140px, 34vw, 168px);
  display: grid; place-items: center;
}

.cb__world { position: relative; transform-style: preserve-3d; width: 1px; height: 1px; }

.cb__bld {
  position: absolute; left: 0; top: 0;
  width: 26px; height: var(--h);
  transform: translate3d(var(--tx), var(--ty), 0) translate(-50%, 0) translateY(calc(var(--h) * -1));
  background: $subject-blue;
  border: 1px solid rgba($subject-ink, .3);
  border-radius: $r-xs $r-xs 0 0;
  box-shadow: $shadow-press;
}

.cb__roof {
  position: absolute; left: 50%; top: 0;
  width: 26px; height: 10px;
  transform: translate3d(-50%, -70%, 0);
  background: $subject-orange-deep;
  border-radius: $r-xs;
}

.cb__win {
  position: absolute; left: 50%; width: 9px; height: 9px;
  transform: translateX(-50%);
  background: $subject-ink;
  border-radius: $r-xs;
  animation: cbTwinkle 3s ease-in-out infinite;
  animation-delay: var(--delay, 0s);
}

@keyframes cbTwinkle {
  0%, 100% { background: $subject-ink; box-shadow: none; }
  50% { background: $stage-yellow; box-shadow: 0 0 9px rgba($stage-yellow, .9); }
}

.cb__meta { margin: 0; font-size: clamp(9px, 2.4vw, 11px); color: rgba($subject-ink, .78); }
.cb__meta b { font-weight: 800; color: $subject-blue; font-variant-numeric: tabular-nums; }

@media (max-width: 340px) {
  .cb { gap: $sp-1; }
  .cb__field { width: 156px; height: 112px; }
  .cb__hint { font-size: 8px; }
  .cb__meta { font-size: 7px; }
}

// reduce — 창문 깜빡임이 멎는다. 중간 밝기(.6)로 고정된 정지 도시만 남긴다.
// (건물 배치는 JS 가 한 번만 그리는 정적 값이라 여기엔 자바스크립트 분기가 필요 없다)
@media (prefers-reduced-motion: reduce) {
  .cb__win { animation: none; background: $stage-yellow; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cb {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: 100%;
  max-width: 420px;
}

.cb__hint {
  margin: 0;
  font-weight: 700;
  font-size: clamp(10px, 2.6vw, 12px);
  line-height: 1.35;
  color: #17141a;
  text-align: center;
}

.cb__field {
  position: relative;
  width: clamp(180px, 42vw, 220px);
  height: clamp(140px, 34vw, 168px);
  display: grid;
  place-items: center;
}

.cb__world {
  position: relative;
  transform-style: preserve-3d;
  width: 1px;
  height: 1px;
}

.cb__bld {
  position: absolute;
  left: 0;
  top: 0;
  width: 26px;
  height: var(--h);
  transform: translate3d(var(--tx), var(--ty), 0) translate(-50%, 0) translateY(calc(var(--h) * -1));
  background: #2f6df6;
  border: 1px solid rgba(23, 20, 26, 0.3);
  border-radius: 4px 4px 0 0;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.cb__roof {
  position: absolute;
  left: 50%;
  top: 0;
  width: 26px;
  height: 10px;
  transform: translate3d(-50%, -70%, 0);
  background: #c93000;
  border-radius: 4px;
}

.cb__win {
  position: absolute;
  left: 50%;
  width: 9px;
  height: 9px;
  transform: translateX(-50%);
  background: #17141a;
  border-radius: 4px;
  animation: cbTwinkle 3s ease-in-out infinite;
  animation-delay: var(--delay, 0s);
}

@keyframes cbTwinkle {
  0%, 100% {
    background: #17141a;
    box-shadow: none;
  }
  50% {
    background: #ffd23f;
    box-shadow: 0 0 9px rgba(255, 210, 63, 0.9);
  }
}
.cb__meta {
  margin: 0;
  font-size: clamp(9px, 2.4vw, 11px);
  color: rgba(23, 20, 26, 0.78);
}

.cb__meta b {
  font-weight: 800;
  color: #2f6df6;
  font-variant-numeric: tabular-nums;
}

@media (max-width: 340px) {
  .cb {
    gap: 4px;
  }
  .cb__field {
    width: 156px;
    height: 112px;
  }
  .cb__hint {
    font-size: 8px;
  }
  .cb__meta {
    font-size: 7px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cb__win {
    animation: none;
    background: #ffd23f;
  }
}

// 도시 블록 씬(08) — mulberry32(Seed  고정) 로 건물 높이와 창문 깜빡임 지연을 뽑는다.
// 같은 시드는 항상 같은 도시를 만든다(재현성). 창문 깜빡임은 진짜 @keyframes 무한
// 애니메이션이라 렌더가 결정론 모드(Animation.currentTime 스크럽)로 잡아 정확히 찍는다.
(function () {
  var root = document.getElementById('cb');
  var world = document.getElementById('world');
  var nEl = document.getElementById('n');
  if (!root || !world || !nEl) return;

  function mulberry32(seed) {
    return function () {
      seed |= 0; seed = (seed + 0x6D2B79F5) | 0;
      var t = Math.imul(seed ^ (seed >>> 15), 1 | seed);
      t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
      return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
    };
  }

  var SEED = 42;
  var rand = mulberry32(SEED);

  function mat4RotateX(deg) {
    var r = deg * Math.PI / 180, c = Math.cos(r), s = Math.sin(r);
    return [1, 0, 0, 0, 0, c, s, 0, 0, -s, c, 0, 0, 0, 0, 1];
  }
  function mat4RotateZ(deg) {
    var r = deg * Math.PI / 180, c = Math.cos(r), s = Math.sin(r);
    return [c, s, 0, 0, -s, c, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1];
  }
  function mat4Mul(a, b) {
    var out = new Array(16);
    for (var col = 0; col < 4; col++) {
      for (var row = 0; row < 4; row++) {
        var sum = 0;
        for (var k = 0; k < 4; k++) sum += a[k * 4 + row] * b[col * 4 + k];
        out[col * 4 + row] = sum;
      }
    }
    return out;
  }
  function mat4ToCss(m) {
    var s = '';
    for (var i = 0; i < m.length; i++) s += (i ? ',' : '') + m[i].toFixed(6);
    return 'matrix3d(' + s + ')';
  }

  world.style.transform = mat4ToCss(mat4Mul(mat4RotateX(-35.264), mat4RotateZ(45)));

  var mm = window.matchMedia('(max-width: 340px)').matches;
  var N = 3;
  var TILE_W = mm ? 30 : 38, TILE_H = mm ? 15 : 19;
  var HMIN = mm ? 24 : 34, HRANGE = mm ? 30 : 44;

  nEl.textContent = String(N * N);
  document.getElementById('seed').textContent = String(SEED);

  for (var row = 0; row < N; row++) {
    for (var col = 0; col < N; col++) {
      var h = HMIN + rand() * HRANGE;   // 건물 높이 — Seed  난수
      var x = (col - row) * TILE_W / 2;
      var y = (col + row) * TILE_H / 2;

      var bld = document.createElement('div');
      bld.className = 'cb__bld';
      bld.style.setProperty('--tx', x.toFixed(2) + 'px');
      bld.style.setProperty('--ty', y.toFixed(2) + 'px');
      bld.style.setProperty('--h', h.toFixed(1) + 'px');
      bld.style.zIndex = String(Math.round((col + row) * 10));
      world.appendChild(bld);

      var roof = document.createElement('div');
      roof.className = 'cb__roof';
      bld.appendChild(roof);

      var winCount = 2 + Math.floor(rand() * 2);   // 2~3개 창문 — Seed  난수
      for (var w = 0; w < winCount; w++) {
        var win = document.createElement('div');
        win.className = 'cb__win';
        var delay = -(rand() * 3).toFixed(2);       // 시작 위상도 Seed  난수 — 창마다 다르게
        win.style.setProperty('--delay', delay + 's');
        win.style.bottom = (10 + w * 13) + 'px';
        bld.appendChild(win);
      }
    }
  }
})();

// IsometricCityBlockScene — vanilla 판(run/333/demo/08-isometric-city-block-scene/index.html)
// 의 React 포트. 건물 높이·창문 개수·깜빡임 지연은 mulberry32(시드 42) 로 한 번만 뽑아
// 고정한다 — 배치는 정적, 창문 깜빡임만 진짜 @keyframes 무한 애니메이션으로 계속 돈다.
import { useEffect, useRef } from "react";
import styles from "./IsometricCityBlockScene.module.scss";

export type IsometricCityBlockSceneProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

const HINT = "건물 높이는 시드 42 난수로, 창문 깜빡임 지연도 같은 시드 난수로 정해 매번 같은 도시가 나옵니다";
const ARIA_FIELD = "높이가 저마다 다른 건물 아홉 채가 늘어서고 창문이 각자 다른 박자로 깜빡이는 도시 블록 장면";
const LABEL_SEED = "시드 ";
const LABEL_BUILDINGS = " · 건물 ";
const LABEL_UNIT = "채";

const SEED = 42;
const N = 3;
const TILE_W = 40, TILE_H = 20;

function mulberry32(seed: number): () => number {
  let a = seed;
  return function (): number {
    a |= 0;
    a = (a + 0x6d2b79f5) | 0;
    let t = Math.imul(a ^ (a >>> 15), 1 | a);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

type Building = { x: number; y: number; h: number; windows: number[] };

export default function IsometricCityBlockScene({
  duration = "3s",
  easing = "ease-in-out",
  color = "#2f6df6"
}: IsometricCityBlockSceneProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const worldRef = useRef<HTMLDivElement | null>(null);
  const countRef = useRef<HTMLElement | null>(null);

  useEffect(() => {
    const world = worldRef.current;
    const root = rootRef.current;
    if (!world || !root) return;

    const rand = mulberry32(SEED);
    const buildings: Building[] = [];
    let minX = Infinity, maxX = -Infinity, maxY = -Infinity;
    for (let row = 0; row < N; row++) {
      for (let col = 0; col < N; col++) {
        const x = ((col - row) * TILE_W) / 2;
        const y = ((col + row) * TILE_H) / 2;
        if (x < minX) minX = x;
        if (x > maxX) maxX = x;
        if (y > maxY) maxY = y;
        const h = 40 + Math.round(rand() * 60);
        const winCount = 2 + Math.round(rand() * 3);
        const windows: number[] = [];
        for (let i = 0; i < winCount; i++) windows.push(rand() * 3);
        buildings.push({ x, y, h, windows });
      }
    }
    const shiftX = -(minX + maxX) / 2;
    const shiftY = -maxY / 2;

    while (world.firstChild) world.removeChild(world.firstChild);
    for (const b of buildings) {
      const bld = document.createElement("div");
      bld.className = styles.bld;
      bld.style.setProperty("--tx", (b.x + shiftX).toFixed(2) + "px");
      bld.style.setProperty("--ty", (b.y + shiftY).toFixed(2) + "px");
      bld.style.setProperty("--h", b.h + "px");

      const roof = document.createElement("div");
      roof.className = styles.roof;
      bld.appendChild(roof);

      const winRows = Math.max(1, Math.floor(b.h / 22));
      let wi = 0;
      for (let r = 0; r < winRows && wi < b.windows.length; r++) {
        const win = document.createElement("div");
        win.className = styles.win;
        win.style.top = 8 + r * 16 + "px";
        win.style.setProperty("--delay", b.windows[wi].toFixed(2) + "s");
        bld.appendChild(win);
        wi++;
      }
      world.appendChild(bld);
    }
    if (countRef.current) countRef.current.textContent = String(buildings.length);

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (reduce) root.classList.add(styles.isStill);

    return () => {
      while (world.firstChild) world.removeChild(world.firstChild);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cb} ref={rootRef} data-duration={duration} data-easing={easing} data-color={color}>
        <p className={styles.hint}>{HINT}</p>
        <div className={styles.field} role="img" aria-label={ARIA_FIELD}>
          <div className={styles.world} ref={worldRef}></div>
        </div>
        <p className={styles.meta}>
          <span>{LABEL_SEED}</span>
          <b>{SEED}</b>
          <span>{LABEL_BUILDINGS}</span>
          <b ref={countRef}>9</b>
          <span>{LABEL_UNIT}</span>
        </p>
      </div>
    </main>
  );
}