Torus przestrzenny

<main class="pen" data-motion="paused"><header><div><h1>Torus przestrzenny</h1><p>Przełącz siatkę na chmurę punktów.</p></div></header><section class="scene" aria-label="Wizualizacja"><canvas id="torus" role="img" aria-label="Trójwymiarowy obracający się torus"></canvas><span class="mesh-label">Model torusa</span></section><div class="toolbar"><button id="motion" type="button" aria-pressed="false">Uruchom</button><label for="mesh-mode">Widok <select id="mesh-mode"><option value="wire">Siatka</option><option value="dots">Punkty</option></select></label><output id="mesh-value" aria-live="polite">Siatka</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:#fbf5dc;--ink:#6a3424;--accent:#9d442e}h1{font-family:Georgia,serif;font-weight:normal}.scene{background:#f5e7b9;border:1px solid #bfa46d}.mesh-label{position:absolute;bottom:15px;right:18px;font:13px monospace}

(() => {

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('#torus');if(!surface)return;const ctx=surface.context,mode=document.querySelector('#mesh-mode');mode.addEventListener('change',()=>{document.querySelector('#mesh-value').value=mode.value==='wire'?'Siatka':'Punkty';if(paint)paint(elapsed);});
function project(x,y,z,time){const a=time*.23+.5,b=time*.19+.75,xx=x*Math.cos(a)+z*Math.sin(a),zz=-x*Math.sin(a)+z*Math.cos(a),yy=y*Math.cos(b)-zz*Math.sin(b),depth=y*Math.sin(b)+zz*Math.cos(b);const scale=Math.min(surface.width,surface.height)*1.25/(4.5+depth);return{x:surface.width/2+xx*scale,y:surface.height/2+yy*scale,z:depth};}
run(time=>{const {width:w,height:h}=surface;ctx.clearRect(0,0,w,h);const points=[];for(let i=0;i<18;i++){const ring=[];for(let j=0;j<36;j++){const u=j/36*Math.PI*2,v=i/18*Math.PI*2,r=1.35+.46*Math.cos(v);ring.push(project(r*Math.cos(u),.46*Math.sin(v),r*Math.sin(u),time));}points.push(ring);}ctx.lineWidth=.8;for(let i=0;i<18;i++)for(let j=0;j<36;j++){const p=points[i][j];ctx.strokeStyle=`rgba(122,57,35,${Math.max(.18,.7-p.z*.17)})`;ctx.fillStyle=ctx.strokeStyle;if(mode.value==='dots'){ctx.beginPath();ctx.arc(p.x,p.y,1.8,0,Math.PI*2);ctx.fill();}else{const next=points[i][(j+1)%36],cross=points[(i+1)%18][j];ctx.beginPath();ctx.moveTo(next.x,next.y);ctx.lineTo(p.x,p.y);ctx.lineTo(cross.x,cross.y);ctx.stroke();}}});
})();