04Loader a Seed-count Value Expands into Voronoi Cells

<main class="stage">
<div class="ld" id="ld">
  <p class="ld__hint">
    <svg class="ld__ico" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 56v56a8 8 0 0 1-16 0V91.3l-25.6 25.7A80 80 0 1 1 174 60a8 8 0 1 1-9 13.2A64 64 0 1 0 179.7 128H216a8 8 0 0 1 0 16h-56a8 8 0 0 1-8-8V80a8 8 0 0 1 16 0v20.7L192.7 76A80.1 80.1 0 0 0 64 128a8 8 0 0 1-16 0a96 96 0 0 1 163.6-68.3L224 71.3V56a8 8 0 0 1 8 8" opacity=".2"/><path d="M224 48a8 8 0 0 0-8 8v15.3l-11.7-11.6a96 96 0 1 0 27.6 51.6a8 8 0 0 0-15.8 2.5a80 80 0 1 1-23-43l-25.7 25.7A8 8 0 0 0 173 112h56a8 8 0 0 0 8-8V56a8 8 0 0 0-13-8"/></g></svg>
    <span>Click or press the space bar to pause or restart</span>
  </p>
  <div class="ld__field" id="field" role="application" aria-label="Voronoi cell growth test panel" tabindex="0">
    <canvas class="ld__cv" id="cv"></canvas>
    <b class="ld__badge" aria-hidden="true"><span class="ld__badgeNum" id="pct">0%</span><span class="ld__badgeUnit">Seeds</span></b>
  </div>
</div>
</main>

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

// 보로노이 셀 로더 — 씨앗점 개수를 진행률에 비례해 늘리고 매 프레임 최근접-씨앗 격자를 다시 계산한다.
// 움직임은 전부 캔버스 rAF 루프 안에 있다. CSS 는 무대·판·배지만 맡는다(@keyframes 0개 — 077 선례와 같은 이유).

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

@include stage($stage-paper);

.ld {
  --paper: #{$subject-cream};
  --ink: #{$subject-ink};
  --c1: #{$subject-blue};
  --c2: #{$subject-mint};
  --c3: #{$subject-pink};
  --c4: #{$subject-lilac};
  --seedpt: #{$subject-ink};

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

.ld__hint {
  display: flex; align-items: center; gap: $sp-1; margin: 0;
  font-weight: 700; font-size: clamp(10px, 2.8vw, 12px); line-height: 1.35;
  color: $subject-ink;
}
.ld__ico { width: 16px; height: 16px; flex: 0 0 auto; color: $subject-blue-deep; }

.ld__field {
  position: relative; height: 208px;
  border-radius: $r-card; overflow: hidden;
  background: $subject-cream;
  box-shadow: inset 0 0 0 1px rgba($subject-ink, .16);
  cursor: pointer;
}
.ld__field:focus-visible { outline: 2px solid $subject-blue-deep; outline-offset: 2px; }

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

.ld__badge {
  position: absolute; right: $sp-2; top: $sp-2;
  display: flex; align-items: baseline; gap: $sp-1;
  padding: $sp-1 $sp-2; border-radius: $r-pill;
  background: rgba($subject-ink, .78);
  color: $subject-cream; font-weight: 700; font-size: 11px;
}
.ld__badgeNum { font-size: 13px; color: $stage-yellow; }
.ld__badgeUnit { font-weight: 700; }

@media (max-width: 340px) {
  .ld { gap: $sp-1; }
  .ld__field { height: 124px; }
  .ld__badge { font-size: 10px; padding: 0 $sp-1; }
  .ld__badgeNum { font-size: 11px; }
}

// reduce — 루프를 시작하지 않고 진행률 62% 언저리에서 멈춘 한 장만 그린다.
@media (prefers-reduced-motion: reduce) {
  .ld.is-still .ld__field { cursor: default !important; }
  .ld.is-still .ld__badge { opacity: .92 !important; }
}

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);
}

.ld {
  --paper: #fff7e6;
  --ink: #17141a;
  --c1: #2f6df6;
  --c2: #4cd4a6;
  --c3: #ff9ebb;
  --c4: #b9a0ff;
  --seedpt: #17141a;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  max-width: 424px;
}

.ld__hint {
  display: flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  font-weight: 700;
  font-size: clamp(10px, 2.8vw, 12px);
  line-height: 1.35;
  color: #17141a;
}

.ld__ico {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
  color: #0a4fe8;
}

.ld__field {
  position: relative;
  height: 208px;
  border-radius: 16px;
  overflow: hidden;
  background: #fff7e6;
  box-shadow: inset 0 0 0 1px rgba(23, 20, 26, 0.16);
  cursor: pointer;
}

.ld__field:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 2px;
}

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

.ld__badge {
  position: absolute;
  right: 8px;
  top: 8px;
  display: flex;
  align-items: baseline;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.78);
  color: #fff7e6;
  font-weight: 700;
  font-size: 11px;
}

.ld__badgeNum {
  font-size: 13px;
  color: #ffd23f;
}

.ld__badgeUnit {
  font-weight: 700;
}

@media (max-width: 340px) {
  .ld {
    gap: 4px;
  }
  .ld__field {
    height: 124px;
  }
  .ld__badge {
    font-size: 10px;
    padding: 0 4px;
  }
  .ld__badgeNum {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ld.is-still .ld__field {
    cursor: default !important;
  }
  .ld.is-still .ld__badge {
    opacity: 0.92 !important;
  }
}

// 보로노이 셀 로더 — 씨앗점 개수를 진행률에 비례해 늘려 매 프레임 보로노이 다이어그램을
// (격자 표본에서 가장 가까운 씨앗 찾기) 다시 계산한다. 셀이 촘촘해질수록 모자이크가 채워진다.
var root = document.getElementById('ld');
var field = document.getElementById('field');
var cv = document.getElementById('cv');
var ctx = cv.getContext('2d');
var pctEl = document.getElementById('pct');

var css = getComputedStyle(root);
var PAPER = css.getPropertyValue('--paper').trim();
var C1 = css.getPropertyValue('--c1').trim();
var C2 = css.getPropertyValue('--c2').trim();
var C3 = css.getPropertyValue('--c3').trim();
var C4 = css.getPropertyValue('--c4').trim();
var SEEDPT = css.getPropertyValue('--seedpt').trim();
var PALETTE = [C1, C2, C3, C4];

function makeRng(seed) {
  var s = seed >>> 0;
  return function () {
    s = (1103515245 * s + 12345) >>> 0;
    return (s >>> 8) / 16777216;
  };
}

var MAXSEEDS = 16;
var LOOP = 2.0;
var CELL = 9;                        // 격자 표본 한 칸(px) — 작을수록 더 매끄러운 다이어그램
var rng = makeRng(20260924);
var seeds = [];
for (var i = 0; i < MAXSEEDS; i++) {
  seeds.push({
    hx: 0.08 + rng() * 0.84, hy: 0.1 + rng() * 0.8, px: 0, py: 0,
    wf: 0.7 + rng() * 1.1, wp: rng() * Math.PI * 2          // 개별 흔들림 진동수·위상(LCG 고정) — 씨앗 수가 그대로여도 경계선이 계속 움직인다
  });
}

var W = 0, H = 0, dpr = 1, cols = 0, rows = 0, wobbleR = 0;

function fit() {
  var r = field.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);
  cols = Math.ceil(W / CELL);
  rows = Math.ceil(H / CELL);
  wobbleR = Math.min(W, H) * 0.035;
  for (var i = 0; i < MAXSEEDS; i++) { seeds[i].hx0 = seeds[i].hx * W; seeds[i].hy0 = seeds[i].hy * H; }
}

function draw(sec) {
  var t = sec % LOOP;
  var p = t / LOOP;                                    // 0→1 진행률 — 활성 씨앗 개수의 목표값
  var count = Math.max(2, 2 + Math.floor(p * (MAXSEEDS - 2)));

  for (var i = 0; i < MAXSEEDS; i++) {
    seeds[i].px = seeds[i].hx0 + Math.sin(sec * seeds[i].wf + seeds[i].wp) * wobbleR;
    seeds[i].py = seeds[i].hy0 + Math.cos(sec * seeds[i].wf * 0.86 + seeds[i].wp) * wobbleR;
  }

  ctx.fillStyle = PAPER;
  ctx.fillRect(0, 0, W, H);

  for (var r = 0; r < rows; r++) {
    var cy = r * CELL + CELL / 2;
    for (var c = 0; c < cols; c++) {
      var cx = c * CELL + CELL / 2;
      var best = 0, bestD = Infinity;
      for (var s = 0; s < count; s++) {
        var dx = cx - seeds[s].px, dy = cy - seeds[s].py;
        var d = dx * dx + dy * dy;
        if (d < bestD) { bestD = d; best = s; }
      }
      ctx.fillStyle = PALETTE[best % PALETTE.length];
      ctx.globalAlpha = 0.55;
      ctx.fillRect(c * CELL, r * CELL, CELL - 1, CELL - 1);
    }
  }
  ctx.globalAlpha = 1;

  for (var k = 0; k < count; k++) {
    ctx.fillStyle = SEEDPT;
    ctx.beginPath();
    ctx.arc(seeds[k].px, seeds[k].py, 3, 0, Math.PI * 2);
    ctx.fill();
  }

  var pct = Math.round((count - 2) / (MAXSEEDS - 2) * 100);
  pctEl.textContent = pct + '%';
}

var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
var paused = false;
var t0 = 0;
var raf = 0;

function togglePause() {
  paused = !paused;
  root.classList.toggle('is-paused', paused);
}
function restart() {
  t0 = performance.now();
  draw(0);
}

field.addEventListener('click', function () { togglePause(); });
field.addEventListener('keydown', function (e) {
  if (e.key === ' ' || e.key === 'Enter') { e.preventDefault(); togglePause(); }
  else if (e.key === 'r' || e.key === 'R') { e.preventDefault(); restart(); }
});
window.addEventListener('resize', function () {
  fit();
  if (paused || reduce) draw(((performance.now() - t0) / 1000));
});

function frame(now) {
  if (!paused) draw((now - t0) / 1000);
  raf = requestAnimationFrame(frame);
}

t0 = performance.now();
fit();
if (reduce) {
  root.classList.add('is-still');
  draw(LOOP * 0.62);
} else {
  raf = requestAnimationFrame(frame);
}

// VoronoiGrow — vanilla 판(run/395/demo/04-canvas-loader-voronoi-cell-grow-seed-count/index.html) 의 React 포트.
// 씨앗점 개수를 진행률에 비례해 늘리고 매 프레임 최근접-씨앗 격자(보로노이)를 다시 계산한다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./VoronoiGrow.module.scss";

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

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };
type Seed = { hx: number; hy: number; px: number; py: number; hx0: number; hy0: number; wf: number; wp: number };

function makeRng(seed: number): () => number {
  let s = seed >>> 0;
  return function () {
    s = (1103515245 * s + 12345) >>> 0;
    return (s >>> 8) / 16777216;
  };
}

const MAXSEEDS = 16;
const LOOP = 2.0;
const CELL = 9;
const FIELD_LABEL = "보로노이 셀 성장 실험판";

function makeSeeds(): Seed[] {
  const rng = makeRng(20260924);
  const list: Seed[] = [];
  for (let i = 0; i < MAXSEEDS; i++) {
    list.push({
      hx: 0.08 + rng() * 0.84, hy: 0.1 + rng() * 0.8, px: 0, py: 0, hx0: 0, hy0: 0,
      wf: 0.7 + rng() * 1.1, wp: rng() * Math.PI * 2,   // 개별 흔들림 진동수·위상(LCG 고정) — 씨앗 수가 그대로여도 경계선이 계속 움직인다
    });
  }
  return list;
}

export default function VoronoiGrow({
  duration = "2s",
  easing = "cubic-bezier(.2, 1.4, .4, 1)",   // vanilla $easing: $ease-pop
  color = "#0a4fe8",                          // vanilla $color: $subject-blue-deep
}: VoronoiGrowProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const fieldRef = useRef<HTMLDivElement | null>(null);
  const cvRef = useRef<HTMLCanvasElement | null>(null);
  const ctxRef = useRef<CanvasRenderingContext2D | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const sizeRef = useRef({ w: 0, h: 0, dpr: 1, cols: 0, rows: 0, wobbleR: 0 }) as Box<{ w: number; h: number; dpr: number; cols: number; rows: number; wobbleR: number }>;
  const seedsRef = useRef<Seed[]>(makeSeeds()) as Box<Seed[]>;
  const pausedRef = useRef(false) as Box<boolean>;
  const t0Ref = useRef(0) as Box<number>;
  const rafRef = useRef(0) as Box<number>;
  const vars: Vars = { "--duration": duration, "--easing": easing, "--color": color };

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

  function fit(): void {
    const field = fieldRef.current;
    const cv = cvRef.current;
    if (!field || !cv) return;
    const r = field.getBoundingClientRect();
    const dpr = window.devicePixelRatio || 1;
    const size = sizeRef.current;
    size.w = r.width; size.h = r.height; size.dpr = dpr;
    cv.width = Math.round(r.width * dpr);
    cv.height = Math.round(r.height * dpr);
    const ctx = ctxRef.current;
    if (ctx) ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    size.cols = Math.ceil(r.width / CELL);
    size.rows = Math.ceil(r.height / CELL);
    size.wobbleR = Math.min(r.width, r.height) * 0.035;
    const seeds = seedsRef.current;
    for (let i = 0; i < MAXSEEDS; i++) { seeds[i].hx0 = seeds[i].hx * r.width; seeds[i].hy0 = seeds[i].hy * r.height; }
  }

  function draw(sec: number): void {
    const ctx = ctxRef.current;
    const root = rootRef.current;
    if (!ctx || !root) return;
    const size = sizeRef.current;
    const W = size.w, H = size.h;
    const t = sec % LOOP;
    const p = t / LOOP;
    const count = Math.max(2, 2 + Math.floor(p * (MAXSEEDS - 2)));
    const seeds = seedsRef.current;
    const wobbleR = size.wobbleR;
    for (let i = 0; i < MAXSEEDS; i++) {
      seeds[i].px = seeds[i].hx0 + Math.sin(sec * seeds[i].wf + seeds[i].wp) * wobbleR;
      seeds[i].py = seeds[i].hy0 + Math.cos(sec * seeds[i].wf * 0.86 + seeds[i].wp) * wobbleR;
    }

    const cssv = (n: string) => getComputedStyle(root).getPropertyValue(n).trim();
    const PAPER = cssv("--paper"), SEEDPT = cssv("--seedpt");
    const PALETTE = [cssv("--c1"), cssv("--c2"), cssv("--c3"), cssv("--c4")];

    ctx.fillStyle = PAPER;
    ctx.fillRect(0, 0, W, H);

    for (let r = 0; r < size.rows; r++) {
      const cy = r * CELL + CELL / 2;
      for (let c = 0; c < size.cols; c++) {
        const cx = c * CELL + CELL / 2;
        let best = 0, bestD = Infinity;
        for (let s = 0; s < count; s++) {
          const dx = cx - seeds[s].px, dy = cy - seeds[s].py;
          const d = dx * dx + dy * dy;
          if (d < bestD) { bestD = d; best = s; }
        }
        ctx.fillStyle = PALETTE[best % PALETTE.length];
        ctx.globalAlpha = 0.55;
        ctx.fillRect(c * CELL, r * CELL, CELL - 1, CELL - 1);
      }
    }
    ctx.globalAlpha = 1;

    for (let k = 0; k < count; k++) {
      ctx.fillStyle = SEEDPT;
      ctx.beginPath();
      ctx.arc(seeds[k].px, seeds[k].py, 3, 0, Math.PI * 2);
      ctx.fill();
    }

    const pct = Math.round((count - 2) / (MAXSEEDS - 2) * 100);
    if (pctRef.current) pctRef.current.textContent = pct + "%";
  }

  function togglePause(): void {
    pausedRef.current = !pausedRef.current;
    const root = rootRef.current;
    if (root) root.classList.toggle("is-paused", pausedRef.current);
  }

  function restart(): void {
    t0Ref.current = performance.now();
    draw(0);
  }

  function onKey(e: KeyEvt): void {
    if (e.key === " " || e.key === "Enter") { e.preventDefault(); togglePause(); }
    else if (e.key === "r" || e.key === "R") { e.preventDefault(); restart(); }
  }

  function onClick(): void {
    togglePause();
  }

  function onResize(): void {
    fit();
    if (pausedRef.current || reduced()) draw((performance.now() - t0Ref.current) / 1000);
  }

  function frame(now: number): void {
    if (!pausedRef.current) draw((now - t0Ref.current) / 1000);
    rafRef.current = requestAnimationFrame(frame);
  }

  useEffect(() => {
    const cv = cvRef.current;
    if (!cv) return;
    ctxRef.current = cv.getContext("2d");
    if (!ctxRef.current) return;
    t0Ref.current = performance.now();
    fit();
    window.addEventListener("resize", onResize);
    if (reduced()) {
      const root = rootRef.current;
      if (root) root.classList.add("is-still");
      draw(LOOP * 0.62);
    } else {
      rafRef.current = requestAnimationFrame(frame);
    }
    return () => {
      window.removeEventListener("resize", onResize);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.root} ref={rootRef} style={vars}>
        <p className={styles.hint}>
          <svg className={styles.ico} viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 56v56a8 8 0 0 1-16 0V91.3l-25.6 25.7A80 80 0 1 1 174 60a8 8 0 1 1-9 13.2A64 64 0 1 0 179.7 128H216a8 8 0 0 1 0 16h-56a8 8 0 0 1-8-8V80a8 8 0 0 1 16 0v20.7L192.7 76A80.1 80.1 0 0 0 64 128a8 8 0 0 1-16 0a96 96 0 0 1 163.6-68.3L224 71.3V56a8 8 0 0 1 8 8" opacity=".2"/><path d="M224 48a8 8 0 0 0-8 8v15.3l-11.7-11.6a96 96 0 1 0 27.6 51.6a8 8 0 0 0-15.8 2.5a80 80 0 1 1-23-43l-25.7 25.7A8 8 0 0 0 173 112h56a8 8 0 0 0 8-8V56a8 8 0 0 0-13-8"/></g></svg>
          <span>클릭하거나 스페이스바를 누르면 멈추거나 다시 갑니다</span>
        </p>
        <div
          className={styles.field}
          ref={fieldRef}
          role="application"
          aria-label={FIELD_LABEL}
          tabIndex={0}
          onClick={onClick}
          onKeyDown={onKey}
        >
          <canvas className={styles.cv} ref={cvRef}></canvas>
          <b className={styles.badge} aria-hidden="true"><span className={styles.badgeNum} ref={pctRef}>0%</span><span className={styles.badgeUnit}>시드</span></b>
        </div>
      </div>
    </main>
  );
}