09Hero grove — a fractal forest growing over the brand line

<main class="stage">
<div class="ls is-demo" id="lsRoot">
  <div class="ls__hero" role="application" aria-label="Hero grove scene" tabindex="0">
    <canvas class="ls__cv" id="lsCv"></canvas>
    <div class="ls__veil" aria-hidden="true"></div>
    <div class="ls__copy">
      <p class="ls__kicker">When one character grows</p>
      <p class="ls__title">FRACTAL<br>FOREST</p>
      <p class="ls__tag" id="lsTag">Rules gather into a forest</p>
    </div>
  </div>
  <div class="ls__bar">
    <span class="ls__meta">Trees <b id="lsCount">5</b> · each a different rule</span>
    <span class="ls__meta ls__meta--dim">canvas · createRadialGradient</span>
  </div>
</div>
</main>

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

// 대문 숲(09). @keyframes 를 두지 않는다 —
// 움직임은 전부 캔버스 rAF 루프(숲 성장+바람 + 방사 그라디언트 호흡)와 JS 가 매기는
// 태그 문구 투명도(캔버스 값과 같은 호흡 위상)가 만든다. 무대는 편 공통 숲 밤 이끼.

$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-mint;

$ls-stage: #1a2116;
@include stage($ls-stage);

$ls-ink:  #12160e;
$ls-ink2: #0a0d07;
$ls-bark: #d8c4a0;
$ls-leaf: #bfe3c8;
$ls-mist: #dfe6d6;

.ls {
  --ls-ink:  #{$ls-ink};
  --ls-ink2: #{$ls-ink2};
  --ls-bark: #{$ls-bark};
  --ls-leaf: #{$ls-leaf};
  --ls-mist: #{$ls-mist};

  display: flex; flex-direction: column; gap: $sp-2;
  width: 100%; max-width: 424px;
}

.ls__hero {
  position: relative; height: 180px;
  border-radius: $r-card; overflow: hidden;
  background: $ls-ink;
  box-shadow: inset 0 0 0 1px rgba($ls-mist, .18);
  display: grid; place-items: center;
}
.ls__hero:focus-visible { outline: 2px solid $subject-mint; outline-offset: 2px; }

.ls__cv { position: absolute; inset: 0; display: block; width: 100%; height: 100%; }

.ls__veil { position: absolute; inset: 0; pointer-events: none; }

.ls__copy {
  position: relative; z-index: 1;
  display: flex; flex-direction: column; align-items: center; gap: $sp-1;
  margin: 0; text-align: center; padding: 0 $sp-3;
}

.ls__kicker {
  margin: 0;
  font-weight: 500; font-size: clamp(9px, 2.4vw, 11px); line-height: 1;
  letter-spacing: .28em;
  color: rgba($ls-mist, .78);
}

.ls__title {
  margin: 0;
  font-weight: 700; font-size: clamp(18px, 6.4vw, 27px); line-height: 1.08;
  letter-spacing: .06em;
  color: $ls-mist;
  text-shadow: 0 2px 12px rgba($ls-ink2, .8);
}

.ls__tag {
  margin: 0;
  font-weight: 500; font-size: 10px; line-height: 1.3;
  color: rgba($ls-mist, .8);
}

.ls__bar { display: flex; align-items: baseline; justify-content: space-between; gap: $sp-2; }
.ls__meta { font-size: 10px; font-weight: 500; color: rgba($ls-mist, .72); }
.ls__meta--dim { font-size: 10px; }
.ls__meta b { font-weight: 700; color: $ls-mist; }

@media (max-width: 340px) {
  .ls { gap: $sp-1; }
  .ls__hero { height: 100px; }
  .ls__meta--dim { display: none; }
  .ls__tag { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .ls.is-still .ls__hero { cursor: default !important; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #1a2116;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ls {
  --ls-ink: #12160e;
  --ls-ink2: #0a0d07;
  --ls-bark: #d8c4a0;
  --ls-leaf: #bfe3c8;
  --ls-mist: #dfe6d6;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  max-width: 424px;
}

.ls__hero {
  position: relative;
  height: 180px;
  border-radius: 16px;
  overflow: hidden;
  background: #12160e;
  box-shadow: inset 0 0 0 1px rgba(223, 230, 214, 0.18);
  display: grid;
  place-items: center;
}

.ls__hero:focus-visible {
  outline: 2px solid #4cd4a6;
  outline-offset: 2px;
}

.ls__cv {
  position: absolute;
  inset: 0;
  display: block;
  width: 100%;
  height: 100%;
}

.ls__veil {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.ls__copy {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  margin: 0;
  text-align: center;
  padding: 0 12px;
}

.ls__kicker {
  margin: 0;
  font-weight: 500;
  font-size: clamp(9px, 2.4vw, 11px);
  line-height: 1;
  letter-spacing: 0.28em;
  color: rgba(223, 230, 214, 0.78);
}

.ls__title {
  margin: 0;
  font-weight: 700;
  font-size: clamp(18px, 6.4vw, 27px);
  line-height: 1.08;
  letter-spacing: 0.06em;
  color: #dfe6d6;
  text-shadow: 0 2px 12px rgba(10, 13, 7, 0.8);
}

.ls__tag {
  margin: 0;
  font-weight: 500;
  font-size: 10px;
  line-height: 1.3;
  color: rgba(223, 230, 214, 0.8);
}

.ls__bar {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
}

.ls__meta {
  font-size: 10px;
  font-weight: 500;
  color: rgba(223, 230, 214, 0.72);
}

.ls__meta--dim {
  font-size: 10px;
}

.ls__meta b {
  font-weight: 700;
  color: #dfe6d6;
}

@media (max-width: 340px) {
  .ls {
    gap: 4px;
  }
  .ls__hero {
    height: 100px;
  }
  .ls__meta--dim {
    display: none;
  }
  .ls__tag {
    display: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ls.is-still .ls__hero {
    cursor: default !important;
  }
}

// 대문 숲(09) — 계산 화면 하나가 서비스 첫 화면이 되는 조립. Trees 다섯 그루가
// 저마다 다른 문자 재쓰기 규칙(F→F[+F]F[-F] 류 세 가지를 섞어)으로 자라 문장 위에 이른다.
// 층 3개: ① 숲 캔버스(gen 성장 + 08 과 같은 깊이비례 바람) ② 방사 그라디언트 비네팅
// (createRadialGradient, 매 프레임 다시 그려 숨쉬듯 짙어졌다 옅어진다) ③ 타이포(kicker·title·tag).
(function () {
  // ── 변형 상수 블록 ──
  var MAXGEN  = 4;
  var CYCLE   = 2.0;
  var N_TREE  = 5;
  // ─────────────────

  var root = document.getElementById('lsRoot');
  var hero = document.getElementById('lsCv').parentElement;
  var cv = document.getElementById('lsCv');
  var tagEl = document.getElementById('lsTag');

  var css = getComputedStyle(root);
  function tokRGB(name) {
    var s = css.getPropertyValue(name).trim();
    var hx = s.length === 4
      ? s.charAt(1) + s.charAt(1) + s.charAt(2) + s.charAt(2) + s.charAt(3) + s.charAt(3)
      : s.slice(1);
    return [parseInt(hx.slice(0, 2), 16), parseInt(hx.slice(2, 4), 16), parseInt(hx.slice(4, 6), 16)];
  }
  var C_BARK = tokRGB('--ls-bark');
  var C_LEAF = tokRGB('--ls-leaf');
  var C_INK  = tokRGB('--ls-ink');
  var C_INK2 = tokRGB('--ls-ink2');

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var raf = 0, t0 = -1;
  var W = 0, H = 0;

  function fit() {
    var r = hero.getBoundingClientRect();
    W = Math.round(r.width); H = Math.round(r.height);
    cv.width = W; cv.height = H;
  }

  // 나무마다 다른 재쓰기 규칙 세 가지를 돌려쓴다 — "각기 다른 규칙으로 자란다"를 문자 그대로 구현
  var RULES = [
    { 'F': 'F[+F]F[-F]' },
    { 'F': 'F[+F][-F]F' },
    { 'F': 'FF[+F][-F]' }
  ];
  function expand(rule, gen) {
    var s = 'F';
    for (var g = 0; g < gen; g++) {
      var out = '';
      for (var i = 0; i < s.length; i++) {
        var ch = s.charAt(i);
        out += rule[ch] !== undefined ? rule[ch] : ch;
      }
      s = out;
    }
    return s;
  }

  var TREES = [];
  (function seed() {
    for (var i = 0; i < N_TREE; i++) {
      var rule = RULES[i % RULES.length];
      TREES.push({
        xFrac: (i + 0.5) / N_TREE,
        str: expand(rule, MAXGEN),
        angle: 20 + (i % 3) * 5,
        scale: 0.85 + (i % 2) * 0.22,
        phase: i * 0.9,
        genDelay: (i % N_TREE) * 0.06
      });
    }
  })();

  function rgb(c, a) { return 'rgba(' + (c[0] | 0) + ',' + (c[1] | 0) + ',' + (c[2] | 0) + ',' + a + ')'; }

  function drawTree(ctx, tr, ox, oy, sc, loop) {
    var str = tr.str;
    var grPhase = Math.min(Math.max(0, (loop - tr.genDelay)) / 0.5, 1);
    var drawUpto = Math.floor(str.length * grPhase);
    var windPhase = loop * Math.PI * 2 * 1.4 + tr.phase;

    var x = 0, y = 0, a = -Math.PI / 2;
    var stack = [];
    var depth = 0, maxDepth = MAXGEN + 1;
    for (var i = 0; i < drawUpto; i++) {
      var ch = str.charAt(i);
      if (ch === 'F') {
        var depthT = depth / maxDepth;
        var sway = 10 * depthT * depthT * Math.sin(windPhase + depth * 0.8) * Math.PI / 180;
        a += sway;
        var segLen = tr.scale * 0.11 * Math.pow(0.72, depth);
        var nx = x + Math.cos(a) * segLen;
        var ny = y + Math.sin(a) * segLen;
        var cr = C_BARK[0] + (C_LEAF[0] - C_BARK[0]) * depthT;
        var cg = C_BARK[1] + (C_LEAF[1] - C_BARK[1]) * depthT;
        var cb = C_BARK[2] + (C_LEAF[2] - C_BARK[2]) * depthT;
        ctx.strokeStyle = 'rgb(' + (cr | 0) + ',' + (cg | 0) + ',' + (cb | 0) + ')';
        ctx.lineWidth = Math.max(0.8, 3 * Math.pow(0.68, depth));
        ctx.beginPath();
        ctx.moveTo(ox + x * sc, oy + y * sc);
        ctx.lineTo(ox + nx * sc, oy + ny * sc);
        ctx.stroke();
        x = nx; y = ny;
      } else if (ch === '[') {
        stack.push({ x: x, y: y, a: a, d: depth });
        depth++;
        a += tr.angle * Math.PI / 180;
      } else if (ch === ']') {
        var st = stack.pop();
        if (st) { x = st.x; y = st.y; a = st.a; depth = st.d; }
        a -= tr.angle * Math.PI / 180;
      } else if (ch === '+') {
        a += tr.angle * Math.PI / 180;
      } else if (ch === '-') {
        a -= tr.angle * Math.PI / 180;
      }
    }
  }

  function render(loop) {
    var ctx = cv.getContext('2d');
    ctx.fillStyle = rgb(C_INK, 1);
    ctx.fillRect(0, 0, W, H);

    var sc = H * 0.98;
    for (var i = 0; i < TREES.length; i++) {
      var tr = TREES[i];
      drawTree(ctx, tr, W * tr.xFrac, H * 0.98, sc, loop);
    }

    // 방사 그라디언트 비네팅 — 문장이 잘 읽히도록 가운데를 밝히고 가장자리를 죽인다.
    // 반지름을 호흡시켜 정지 구간에도 픽셀이 계속 갱신된다.
    var breath = 0.5 + 0.5 * Math.sin(loop * Math.PI * 2 * 0.6);
    var gx = W * 0.5, gy = H * 0.42;
    var r0 = Math.min(W, H) * (0.08 + 0.02 * breath);
    var r1 = Math.max(W, H) * 0.75;
    var grad = ctx.createRadialGradient(gx, gy, r0, gx, gy, r1);
    grad.addColorStop(0, rgb(C_INK, 0));
    grad.addColorStop(0.55, rgb(C_INK, 0.18 + 0.06 * breath));
    grad.addColorStop(1, rgb(C_INK2, 0.86));
    ctx.fillStyle = grad;
    ctx.fillRect(0, 0, W, H);

    if (tagEl) tagEl.style.opacity = String((0.62 + 0.38 * breath).toFixed(2));
  }

  function frame(now) {
    if (t0 < 0) t0 = now;
    var loop = (((now - t0) / 1000) % CYCLE) / CYCLE;
    render(loop);
    raf = requestAnimationFrame(frame);
  }

  window.addEventListener('resize', function () {
    fit();
    render(0.9);
  });

  fit();
  if (reduce) {
    render(0.9);
    root.classList.add('is-still');
  } else {
    raf = requestAnimationFrame(frame);
  }
})();

// LsysHeroScene — vanilla 판(run/328/demo/09-lsys-hero-scene/index.html) 의 React 포트.
// 계산 화면 하나가 서비스 첫 화면이 되는 조립. 나무 다섯 그루가 저마다 다른 문자 재쓰기 규칙
// (F→F[+F]F[-F] 류 세 가지를 섞어)으로 자라 문장 위에 이른다.
// 층 3개: ① 숲 캔버스(세대 성장 + 08 과 같은 깊이비례 바람) ② 방사 그라디언트 비네팅
// (createRadialGradient, 매 프레임 다시 그려 숨쉬듯 짙어졌다 옅어진다) ③ 타이포(kicker·title·tag).
import { useEffect, useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./LsysHeroScene.module.scss";

export type LsysHeroSceneProps = {
  duration?: string;
  easing?: string;
  color?: string;
  maxGen?: number;
  cycle?: number;
  nTree?: number;
};

const MAXGEN = 4;
const CYCLE = 2.0;
const N_TREE = 5;

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Box<T> = { current: T };
type RGB = [number, number, number];
type Stack = { x: number; y: number; a: number; d: number };
type Tree = { xFrac: number; str: string; angle: number; scale: number; phase: number; genDelay: number };

const KICKER_TEXT = "문자 하나가 자라면";
const TITLE_LINE1 = "FRACTAL";
const TITLE_LINE2 = "FOREST";
const TAG_TEXT = "규칙이 모여 숲이 됩니다";
const META_LEFT_PREFIX = "나무 ";
const META_LEFT_SUFFIX = "그루 · 규칙 각각 다름";
const META_RIGHT = "canvas · createRadialGradient";
const HERO_LABEL = "대문 숲 히어로 씬";

const RULES: Record<string, string>[] = [
  { F: "F[+F]F[-F]" },
  { F: "F[+F][-F]F" },
  { F: "FF[+F][-F]" }
];
function expand(rule: Record<string, string>, gen: number): string {
  let s = "F";
  for (let g = 0; g < gen; g++) {
    let out = "";
    for (let i = 0; i < s.length; i++) {
      const ch = s.charAt(i);
      out += rule[ch] !== undefined ? rule[ch] : ch;
    }
    s = out;
  }
  return s;
}

function seedTrees(nTree: number, maxGen: number): Tree[] {
  const trees: Tree[] = [];
  for (let i = 0; i < nTree; i++) {
    const rule = RULES[i % RULES.length];
    trees.push({
      xFrac: (i + 0.5) / nTree,
      str: expand(rule, maxGen),
      angle: 20 + (i % 3) * 5,
      scale: 0.85 + (i % 2) * 0.22,
      phase: i * 0.9,
      genDelay: (i % nTree) * 0.06
    });
  }
  return trees;
}

function rgb(c: RGB, a: number): string {
  return "rgba(" + (c[0] | 0) + "," + (c[1] | 0) + "," + (c[2] | 0) + "," + a + ")";
}

export default function LsysHeroScene({
  duration = "2s",
  easing = "ease-spring",
  color = "#4cd4a6",
  maxGen = MAXGEN,
  cycle = CYCLE,
  nTree = N_TREE
}: LsysHeroSceneProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const heroRef = useRef<HTMLDivElement | null>(null);
  const cvRef = useRef<HTMLCanvasElement | null>(null);
  const tagRef = useRef<HTMLParagraphElement | null>(null);
  const colRef = useRef<{ bark: RGB; leaf: RGB; ink: RGB; ink2: RGB } | null>(null);
  const treesRef = useRef<Tree[]>([]) as Box<Tree[]>;
  const wRef = useRef(0) as Box<number>;
  const hRef = useRef(0) as Box<number>;
  const rafRef = useRef(0) as Box<number>;
  const [still, setStill] = useState(false);
  const vars: Vars = { "--duration": duration, "--easing": easing, "--color": color };

  function reduced(): boolean {
    return window.matchMedia("(prefers-reduced-motion: reduce)").matches;
  }

  function tokRGB(root: HTMLDivElement, name: string): RGB {
    const s = getComputedStyle(root).getPropertyValue(name).trim();
    const hx = s.length === 4
      ? s.charAt(1) + s.charAt(1) + s.charAt(2) + s.charAt(2) + s.charAt(3) + s.charAt(3)
      : s.slice(1);
    return [parseInt(hx.slice(0, 2), 16), parseInt(hx.slice(2, 4), 16), parseInt(hx.slice(4, 6), 16)];
  }

  function fit(): void {
    const hero = heroRef.current;
    const cv = cvRef.current;
    if (!hero || !cv) return;
    const r = hero.getBoundingClientRect();
    wRef.current = Math.round(r.width);
    hRef.current = Math.round(r.height);
    cv.width = wRef.current;
    cv.height = hRef.current;
  }

  function drawTree(ctx: CanvasRenderingContext2D, tr: Tree, ox: number, oy: number, sc: number, loop: number): void {
    const col = colRef.current;
    if (!col) return;
    const str = tr.str;
    const grPhase = Math.min(Math.max(0, loop - tr.genDelay) / 0.5, 1);
    const drawUpto = Math.floor(str.length * grPhase);
    const windPhase = loop * Math.PI * 2 * 1.4 + tr.phase;

    let x = 0, y = 0, a = -Math.PI / 2;
    const stack: Stack[] = [];
    let depth = 0;
    const maxDepth = maxGen + 1;
    for (let i = 0; i < drawUpto; i++) {
      const ch = str.charAt(i);
      if (ch === "F") {
        const depthT = depth / maxDepth;
        const sway = 10 * depthT * depthT * Math.sin(windPhase + depth * 0.8) * Math.PI / 180;
        a += sway;
        const segLen = tr.scale * 0.11 * Math.pow(0.72, depth);
        const nx = x + Math.cos(a) * segLen;
        const ny = y + Math.sin(a) * segLen;
        const cr = col.bark[0] + (col.leaf[0] - col.bark[0]) * depthT;
        const cg = col.bark[1] + (col.leaf[1] - col.bark[1]) * depthT;
        const cb = col.bark[2] + (col.leaf[2] - col.bark[2]) * depthT;
        ctx.strokeStyle = "rgb(" + (cr | 0) + "," + (cg | 0) + "," + (cb | 0) + ")";
        ctx.lineWidth = Math.max(0.8, 3 * Math.pow(0.68, depth));
        ctx.beginPath();
        ctx.moveTo(ox + x * sc, oy + y * sc);
        ctx.lineTo(ox + nx * sc, oy + ny * sc);
        ctx.stroke();
        x = nx; y = ny;
      } else if (ch === "[") {
        stack.push({ x, y, a, d: depth });
        depth++;
        a += tr.angle * Math.PI / 180;
      } else if (ch === "]") {
        const st = stack.pop();
        if (st) { x = st.x; y = st.y; a = st.a; depth = st.d; }
        a -= tr.angle * Math.PI / 180;
      } else if (ch === "+") {
        a += tr.angle * Math.PI / 180;
      } else if (ch === "-") {
        a -= tr.angle * Math.PI / 180;
      }
    }
  }

  function render(loop: number): void {
    const cv = cvRef.current;
    const col = colRef.current;
    const TREES = treesRef.current;
    const W = wRef.current, H = hRef.current;
    if (!cv || !col) return;
    const ctx = cv.getContext("2d");
    if (!ctx) return;
    ctx.fillStyle = rgb(col.ink, 1);
    ctx.fillRect(0, 0, W, H);

    const sc = H * 0.98;
    for (let i = 0; i < TREES.length; i++) {
      const tr = TREES[i];
      drawTree(ctx, tr, W * tr.xFrac, H * 0.98, sc, loop);
    }

    const breath = 0.5 + 0.5 * Math.sin(loop * Math.PI * 2 * 0.6);
    const gx = W * 0.5, gy = H * 0.42;
    const r0 = Math.min(W, H) * (0.08 + 0.02 * breath);
    const r1 = Math.max(W, H) * 0.75;
    const grad = ctx.createRadialGradient(gx, gy, r0, gx, gy, r1);
    grad.addColorStop(0, rgb(col.ink, 0));
    grad.addColorStop(0.55, rgb(col.ink, 0.18 + 0.06 * breath));
    grad.addColorStop(1, rgb(col.ink2, 0.86));
    ctx.fillStyle = grad;
    ctx.fillRect(0, 0, W, H);

    const tagEl = tagRef.current;
    if (tagEl) tagEl.style.opacity = (0.62 + 0.38 * breath).toFixed(2);
  }

  let t0 = -1;
  function frame(now: number): void {
    if (t0 < 0) t0 = now;
    const loop = (((now - t0) / 1000) % cycle) / cycle;
    render(loop);
    rafRef.current = requestAnimationFrame(frame);
  }

  useEffect(() => {
    const root = rootRef.current;
    const cv = cvRef.current;
    if (!root || !cv) return;
    colRef.current = {
      bark: tokRGB(root, "--ls-bark"),
      leaf: tokRGB(root, "--ls-leaf"),
      ink: tokRGB(root, "--ls-ink"),
      ink2: tokRGB(root, "--ls-ink2")
    };
    treesRef.current = seedTrees(nTree, maxGen);
    fit();
    const reduce = reduced();
    function onResize(): void {
      fit();
      render(0.9);
    }
    window.addEventListener("resize", onResize);
    if (reduce) {
      render(0.9);
      setStill(true);
    } else {
      t0 = -1;
      rafRef.current = requestAnimationFrame(frame);
    }
    return () => {
      window.removeEventListener("resize", onResize);
      cancelAnimationFrame(rafRef.current);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [maxGen, cycle, nTree]);

  const rootCls = still ? `${styles.root} ${styles.isStill}` : styles.root;

  return (
    <main className={styles.stage}>
      <div className={rootCls} ref={rootRef} style={vars}>
        <div className={styles.hero} ref={heroRef} role="application" aria-label={HERO_LABEL} tabIndex={0}>
          <canvas className={styles.cv} ref={cvRef}></canvas>
          <div className={styles.veil} aria-hidden="true"></div>
          <div className={styles.copy}>
            <p className={styles.kicker}>{KICKER_TEXT}</p>
            <p className={styles.title}>{TITLE_LINE1}<br />{TITLE_LINE2}</p>
            <p className={styles.tag} ref={tagRef}>{TAG_TEXT}</p>
          </div>
        </div>
        <div className={styles.bar}>
          <span className={styles.meta}>{META_LEFT_PREFIX}<b>{nTree}</b>{META_LEFT_SUFFIX}</span>
          <span className={`${styles.meta} ${styles.metaDim}`}>{META_RIGHT}</span>
        </div>
      </div>
    </main>
  );
}