Rysownik: harmonograf

<main class="pen" data-motion="paused"><header><div><h1>Rysownik: harmonograf</h1><p>Dwa wahadła kreślą wspólny ślad. Wybierz częstotliwości.</p></div></header><section class="scene" aria-label="Wizualizacja"><canvas id="harmonograph" role="img" aria-label="Rysunek harmonografu"></canvas></section><div class="toolbar"><button id="motion" type="button" aria-pressed="false">Uruchom</button><label for="pattern">Układ <select id="pattern"><option value="3,2">3 : 2</option><option value="5,4">5 : 4</option><option value="7,3">7 : 3</option></select></label><button id="reset" type="button">Nowy rysunek</button><output id="drawing-status" aria-live="polite">Rysowanie</output></div></main>

* { box-sizing: border-box; }
html, body { margin: 0; min-width: 280px; }
body { background: var(--paper); color: var(--ink); font: 16px/1.5 Arial, sans-serif; }
.pen { min-height: 100vh; padding: clamp(16px, 3vw, 30px); display: flex; flex-direction: column; gap: 16px; max-width: 1120px; margin: auto; }
header { display: flex; align-items: baseline; justify-content: space-between; gap: 20px; flex-wrap: wrap; }
h1 { font-size: clamp(26px, 4.1vw, 42px); line-height: 1.08; margin: 0 0 8px; letter-spacing: -.04em; }
p { margin: 0; max-width: 64ch; }
.scene { position: relative; min-height: 230px; flex: 1; display: grid; place-items: center; overflow: hidden; }
.scene canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.toolbar { display: flex; align-items: center; flex-wrap: wrap; gap: 12px 20px; }
.toolbar label { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; min-height: 44px; }
button, select { font: inherit; color: var(--ink); background: var(--paper); border: 1px solid currentColor; border-radius: 0; min-height: 44px; padding: 8px 15px; cursor: pointer; }
button:hover { background: var(--ink); color: var(--paper); }
button:focus-visible, select:focus-visible, input:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
input[type=range] { width: 145px; max-width: 42vw; accent-color: var(--accent); min-height: 36px; cursor: pointer; }
output, .hint { font-size: 14px; }
[data-motion="paused"] .animated { animation-play-state: paused !important; }
@media (max-width: 500px) { header { gap: 6px; } .scene { min-height: 280px; } .toolbar { gap: 10px; } .toolbar label { font-size: 14px; } }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition-duration: 0s !important; scroll-behavior: auto !important; } }
body{--paper:#f7f7f0;--ink:#193e33;--accent:#176753}h1{font-family:Georgia,serif;font-weight:normal}.scene{background:#f7f7f0;border:1px solid #93aea2}.scene::before,.scene::after{content:"";position:absolute;background:#d7e1d9;z-index:-1}.scene::before{height:1px;width:90%}.scene::after{width:1px;height:90%}

(() => {

const root = document.querySelector('.pen');
const preference = matchMedia('(prefers-reduced-motion: reduce)');
const motionButton = document.querySelector('#motion');
let playing = !preference.matches, elapsed = 0, paint = null;
function syncMotion() {
  root.dataset.motion = playing ? 'running' : 'paused';
  motionButton.textContent = playing ? 'Wstrzymaj' : 'Uruchom';
  motionButton.setAttribute('aria-pressed', String(playing));
}
motionButton.addEventListener('click', () => { playing = !playing; syncMotion(); });
preference.addEventListener('change', event => { playing = !event.matches; syncMotion(); });
syncMotion();
function run(draw) {
  paint = draw;
  draw(0);
  let last = performance.now(), lastPaint = 0;
  function frame(now) {
    if (playing && !document.hidden) { elapsed += Math.min(now - last, 48) / 1000; if (now - lastPaint >= 30) { draw(elapsed); lastPaint = now; } }
    last = now;
    requestAnimationFrame(frame);
  }
  requestAnimationFrame(frame);
}
function canvasSurface(selector) {
  const canvas = document.querySelector(selector), context = canvas.getContext('2d');
  if (!context) { canvas.replaceWith(document.createTextNode('Ta wizualizacja wymaga obsługi Canvas 2D.')); return null; }
  const surface = { canvas, context, width: 0, height: 0 };
  function resize() {
    const box = canvas.parentElement.getBoundingClientRect(), ratio = Math.min(devicePixelRatio || 1, 2);
    surface.width = box.width; surface.height = box.height;
    canvas.width = Math.max(1, Math.round(box.width * ratio)); canvas.height = Math.max(1, Math.round(box.height * ratio));
    context.setTransform(ratio, 0, 0, ratio, 0, 0);
    if (paint) paint(elapsed);
  }
  resize(); new ResizeObserver(resize).observe(canvas.parentElement);
  return surface;
}
const surface=canvasSurface('#harmonograph');if(!surface)return;const ctx=surface.context,choice=document.querySelector('#pattern');let origin=0;
function reset(){origin=elapsed;document.querySelector('#drawing-status').value='Nowy rysunek';if(paint)paint(elapsed);}
choice.addEventListener('change',reset);document.querySelector('#reset').addEventListener('click',reset);
run(time=>{const {width:w,height:h}=surface,t=Math.min(35,time-origin+18),[a,b]=choice.value.split(',').map(Number);ctx.clearRect(0,0,w,h);ctx.strokeStyle='#176753';ctx.lineWidth=1.5;ctx.beginPath();const steps=Math.min(1100,Math.ceil(t*32));for(let i=0;i<=steps;i++){const s=i/32,damping=Math.exp(-s*.026),x=w/2+Math.sin(a*s+.6)*Math.min(w*.39,h*.43)*damping,y=h/2+Math.sin(b*s)*h*.41*damping;if(i)ctx.lineTo(x,y);else ctx.moveTo(x,y);}ctx.stroke();if(t>=35){playing=false;syncMotion();document.querySelector('#drawing-status').value='Rysunek ukończony';}});
})();