021行の規則番号の値が次の行の模様を決めるストライプ・オートマトン

<main class="stage">
  <div class="rv is-demo" tabindex="0" role="button" aria-label="ルールストリップ進行中 — クリックまたはスペースキーで停止、R で再シード">
    <canvas class="rv__cv" width="480" height="300"></canvas>
    <p class="rv__hint">クリックまたはスペースキーで停止、R で再シード</p>
  </div>
</main>

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

@include stage($stage-yellow);

.rv {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  aspect-ratio: 480 / 300;
  margin: 0 auto;
  border-radius: $r-card;
  overflow: hidden;
  cursor: pointer;
  box-shadow: $shadow-raised;
  outline-offset: 4px;

  &:focus-visible {
    outline: 3px solid $subject-ink;
  }
}

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

.rv__hint {
  position: absolute;
  left: $sp-3;
  bottom: $sp-3;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  font-size: 12px;
  line-height: 1.4;
  font-weight: 500;
  background: rgba(255, 247, 230, .85);
  color: $subject-ink;
  pointer-events: none;
}

@media (prefers-reduced-motion: reduce) {
  .rv {
    cursor: pointer;
  }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.rv {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  aspect-ratio: 480/300;
  margin: 0 auto;
  border-radius: 16px;
  overflow: hidden;
  cursor: pointer;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  outline-offset: 4px;
}
.rv:focus-visible {
  outline: 3px solid #17141a;
}

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

.rv__hint {
  position: absolute;
  left: 12px;
  bottom: 12px;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 12px;
  line-height: 1.4;
  font-weight: 500;
  background: rgba(255, 247, 230, 0.85);
  color: #17141a;
  pointer-events: none;
}

@media (prefers-reduced-motion: reduce) {
  .rv {
    cursor: pointer;
  }
}

(function(){
  'use strict';
  // 395-09(진행률 채움 로더)와 다른 축: 규칙 번호 값이 다음 줄 무늬를 직접 결정하는 계산이 주인공.
  // 매 세대 한 줄을 규칙표와 대조해 계산하고 화면 전체를 아래로 밀어 fillRect 로 다시 그린다.

  function makeLcg(seed){
    let s = seed >>> 0;
    return function(){
      s = (s * 1664525 + 1013904223) >>> 0;
      return s / 4294967296;
    };
  }

  const W = 480, H = 300;
  const CELL = 5, COLS = W / CELL, ROWS = H / CELL;
  const YELLOW = '#d2c7a4';
  const ALIVE_COLOR = '#93a4ca';
  let SEED = 30071;
  let rnd = makeLcg(SEED);

  const RULE = 30; // 울프럼 초등 오토마타 규칙 번호(이진 8비트) — 왼쪽·자신·오른쪽 조합마다 생사 결정
  const ruleBits = new Uint8Array(8);
  for (let p = 0; p < 8; p++) ruleBits[p] = (RULE >> p) & 1;

  let grid = new Uint8Array(COLS * ROWS);

  function idx(x, y){ return y * COLS + x; }

  function clearGrid(){
    grid.fill(0);
  }

  function seedRow(seedX){
    grid[idx(seedX, ROWS - 1)] = 1;
  }

  function step(){
    grid.copyWithin(0, COLS, ROWS * COLS);
    const base = (ROWS - 2) * COLS;
    const outBase = (ROWS - 1) * COLS;
    for (let x = 0; x < COLS; x++){
      const l = grid[base + ((x - 1 + COLS) % COLS)];
      const m = grid[base + x];
      const r = grid[base + ((x + 1) % COLS)];
      const pattern = l * 4 + m * 2 + r;
      grid[outBase + x] = ruleBits[pattern];
    }
  }

  const cvEl = document.querySelector('.rv__cv');
  const ctx = cvEl.getContext('2d');
  const rootEl = document.querySelector('.rv');

  function render(){
    ctx.fillStyle = YELLOW;
    ctx.fillRect(0, 0, W, H);
    ctx.fillStyle = ALIVE_COLOR;
    for (let y = 0; y < ROWS; y++){
      for (let x = 0; x < COLS; x++){
        if (grid[idx(x, y)] === 1){
          ctx.fillRect(x * CELL, y * CELL, CELL - 1, CELL - 1);
        }
      }
    }
  }

  const ARIA_PLAY = 'ルールストリップ進行中 — クリックまたはスペースキーで停止、R で再シード';
  const ARIA_PAUSE = 'ルールストリップ停止中 — クリックまたはスペースキーで再生、R で再シード';

  function updateAria(){
    rootEl.setAttribute('aria-label', paused ? ARIA_PAUSE : ARIA_PLAY);
  }

  let paused = false;
  const reduceMQ = window.matchMedia('(prefers-reduced-motion: reduce)');

  function human(){ rootEl.classList.remove('is-demo'); }

  function reseed(){
    SEED = (SEED * 1103515245 + 12345) >>> 0;
    rnd = makeLcg(SEED || 1);
    clearGrid();
    const seedX = Math.floor(rnd() * COLS);
    seedRow(seedX);
  }

  function togglePause(){
    paused = !paused;
    updateAria();
  }

  function onActivate(e){
    if (e.type === 'keydown'){
      if (e.key === 'r' || e.key === 'R'){
        human();
        reseed();
        render();
        return;
      }
      if (e.key !== 'Enter' && e.key !== ' ') return;
      e.preventDefault();
    }
    human();
    if (reduceMQ.matches){
      step();
      render();
    } else {
      togglePause();
    }
  }

  function onKey(e){
    if (e.key === 'r' || e.key === 'R' || e.key === 'Enter' || e.key === ' '){
      onActivate(e);
    }
  }

  const GEN_INTERVAL_MS = 32;
  let acc = 0, last = 0;

  function frame(now){
    if (!reduceMQ.matches){
      if (!last) last = now;
      const dt = now - last;
      last = now;
      if (!paused){
        acc += dt;
        while (acc >= GEN_INTERVAL_MS){
          step();
          acc -= GEN_INTERVAL_MS;
        }
        render();
      }
      requestAnimationFrame(frame);
    }
  }

  function onResize(){ render(); }

  rootEl.addEventListener('click', onActivate);
  rootEl.addEventListener('keydown', onKey);
  window.addEventListener('resize', onResize);

  clearGrid();
  seedRow(Math.floor(COLS / 2));
  updateAria();
  render();
  if (!reduceMQ.matches){
    requestAnimationFrame(frame);
  }

})();

import { useEffect, useRef } from 'react';
import styles from './ElementaryRuleStrip.module.scss';

function ctx2d(cv: HTMLCanvasElement): CanvasRenderingContext2D {
  const c = cv.getContext('2d');
  if (!c) throw new Error('no 2d context');
  return c;
}

function makeLcg(seed: number): () => number {
  let s = seed >>> 0;
  return function(){
    s = (s * 1664525 + 1013904223) >>> 0;
    return s / 4294967296;
  };
}

const W = 480, H = 300;
const CELL = 5, COLS = W / CELL, ROWS = H / CELL;
const YELLOW = '#d2c7a4';
const ALIVE_COLOR = '#93a4ca';
let SEED = 30071;
let rnd = makeLcg(SEED);

const RULE = 30; // 울프럼 초등 오토마타 규칙 번호(이진 8비트) — 왼쪽·자신·오른쪽 조합마다 생사 결정
const ruleBits = new Uint8Array(8);
for (let p = 0; p < 8; p++) ruleBits[p] = (RULE >> p) & 1;

const grid = new Uint8Array(COLS * ROWS);

function idx(x: number, y: number): number { return y * COLS + x; }

function clearGrid(): void {
  grid.fill(0);
}

function seedRow(seedX: number): void {
  grid[idx(seedX, ROWS - 1)] = 1;
}

function step(): void {
  grid.copyWithin(0, COLS, ROWS * COLS);
  const base = (ROWS - 2) * COLS;
  const outBase = (ROWS - 1) * COLS;
  for (let x = 0; x < COLS; x++){
    const l = grid[base + ((x - 1 + COLS) % COLS)];
    const m = grid[base + x];
    const r = grid[base + ((x + 1) % COLS)];
    const pattern = l * 4 + m * 2 + r;
    grid[outBase + x] = ruleBits[pattern];
  }
}

function render(ctx: CanvasRenderingContext2D): void {
  ctx.fillStyle = YELLOW;
  ctx.fillRect(0, 0, W, H);
  ctx.fillStyle = ALIVE_COLOR;
  for (let y = 0; y < ROWS; y++){
    for (let x = 0; x < COLS; x++){
      if (grid[idx(x, y)] === 1){
        ctx.fillRect(x * CELL, y * CELL, CELL - 1, CELL - 1);
      }
    }
  }
}

const ARIA_PLAY = '규칙 스트립 진행 중 — 클릭하거나 스페이스바로 정지, R 로 재시드';
const ARIA_PAUSE = '규칙 스트립 정지됨 — 클릭하거나 스페이스바로 재생, R 로 재시드';

export default function ElementaryRuleStrip(){

  const rootRef = useRef<HTMLDivElement | null>(null);
  const cvRef = useRef<HTMLCanvasElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const cv = cvRef.current;
    if (!root || !cv) return;
    const rootEl: HTMLDivElement = root;
    const cvEl: HTMLCanvasElement = cv;
    const ctx = ctx2d(cvEl);

    function updateAria(): void {
      rootEl.setAttribute('aria-label', paused ? ARIA_PAUSE : ARIA_PLAY);
    }

    let paused = false;
    const reduceMQ = window.matchMedia('(prefers-reduced-motion: reduce)');

    function human(): void { rootEl.classList.remove('is-demo'); }

    function reseed(): void {
      SEED = (SEED * 1103515245 + 12345) >>> 0;
      rnd = makeLcg(SEED || 1);
      clearGrid();
      const seedX = Math.floor(rnd() * COLS);
      seedRow(seedX);
    }

    function togglePause(): void {
      paused = !paused;
      updateAria();
    }

    function onActivate(e: Event): void {
      if (e.type === 'keydown'){
        const ke = e as KeyboardEvent;
        if (ke.key === 'r' || ke.key === 'R'){
          human();
          reseed();
          render(ctx);
          return;
        }
        if (ke.key !== 'Enter' && ke.key !== ' ') return;
        ke.preventDefault();
      }
      human();
      if (reduceMQ.matches){
        step();
        render(ctx);
      } else {
        togglePause();
      }
    }

    const GEN_INTERVAL_MS = 32;
    let acc = 0, last = 0, rafId = 0;

    function frame(now: number): void {
      if (!reduceMQ.matches){
        if (!last) last = now;
        const dt = now - last;
        last = now;
        if (!paused){
          acc += dt;
          while (acc >= GEN_INTERVAL_MS){
            step();
            acc -= GEN_INTERVAL_MS;
          }
          render(ctx);
        }
        rafId = requestAnimationFrame(frame);
      }
    }

    function onResize(): void { render(ctx); }

    rootEl.addEventListener('click', onActivate);
    rootEl.addEventListener('keydown', onActivate);
    window.addEventListener('resize', onResize);

    clearGrid();
    seedRow(Math.floor(COLS / 2));
    updateAria();
    render(ctx);
    if (!reduceMQ.matches){
      rafId = requestAnimationFrame(frame);
    }

    return () => {
      rootEl.removeEventListener('click', onActivate);
      rootEl.removeEventListener('keydown', onActivate);
      window.removeEventListener('resize', onResize);
      if (rafId) cancelAnimationFrame(rafId);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div ref={rootRef} className={`${styles.rv} is-demo`} tabIndex={0} role="button" aria-label="규칙 스트립 진행 중 — 클릭하거나 스페이스바로 정지, R 로 재시드">
        <canvas ref={cvRef} className={styles.rv__cv} width={480} height={300} />
        <p className={styles.rv__hint}>클릭·스페이스바로 정지, R 로 재시드</p>
      </div>
    </main>
  );
}