quimbot/docs/gallery/julia.html at main · milwrite/quimbot · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
  <link rel="icon" type="image/png" href="../favicon.png">
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Julia Set</title>
<style>
  *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
  html, body { width: 100%; height: 100%; background: #050508; overflow: hidden; }
  canvas { display: block; width: 100vw; height: 100vh; image-rendering: pixelated; touch-action: none; }
  #label {
    position: fixed; top: calc(12px + env(safe-area-inset-top)); left: calc(12px + env(safe-area-inset-left));
    color: rgba(255,255,255,0.45); font: 12px/1.4 ui-monospace, monospace;
    pointer-events: none; letter-spacing: 0.06em;
  }
  #params {
    position: fixed; bottom: calc(12px + env(safe-area-inset-bottom)); left: calc(12px + env(safe-area-inset-left));
    color: rgba(255,255,255,0.35); font: 11px ui-monospace, monospace;
    pointer-events: none; letter-spacing: 0.04em;
  }
  #hint {
    position: fixed; bottom: calc(12px + env(safe-area-inset-bottom)); right: calc(12px + env(safe-area-inset-right));
    color: rgba(255,255,255,0.28); font: 11px ui-monospace, monospace;
    pointer-events: none; text-align: right;
  }
  .back-btn {
    position: fixed; top: calc(12px + env(safe-area-inset-top)); right: calc(12px + env(safe-area-inset-right));
    background: rgba(20,20,20,0.8); border: 1px solid #444; color: #e0e0e0;
    padding: 8px 14px; border-radius: 6px; font: 12px ui-monospace, monospace;
    cursor: pointer; text-decoration: none; backdrop-filter: blur(8px);
    z-index: 100; transition: border-color 0.2s;
  }
  .back-btn:hover { border-color: #888; }
  .in-iframe .back-btn, .in-iframe #label, .in-iframe #params, .in-iframe #hint { display: none; }
</style>
</head>
<body>
<script>if (window.self !== window.top) document.body.classList.add('in-iframe');</script>
<a href="./" class="back-btn">← Gallery</a>
<div id="label">Julia Set</div>
<div id="params" id="params">c = 0 + 0i</div>
<div id="hint">move mouse to steer c · click to lock</div>
<canvas id="c"></canvas>

<script>
'use strict';

const canvas  = document.getElementById('c');
const ctx     = canvas.getContext('2d');
const paramsEl = document.getElementById('params');
const hintEl   = document.getElementById('hint');

// Render into a half-resolution offscreen buffer
let RW, RH; // render dimensions
let imgData, pixels;
let W, H, dpr;

// Julia parameter c
let cReal = -0.7269, cImag = 0.1889; // default: dendrite-ish
let locked = false;
let dirty  = true;

// Preset c values with names — cycle through on click when locked
const PRESETS = [
  { r: -0.7269, i:  0.1889, name: 'dendrite' },
  { r: -0.4,    i:  0.6,    name: 'seahorse' },
  { r:  0.285,  i:  0.01,   name: 'rabbit' },
  { r: -0.835,  i: -0.2321, name: 'dragon' },
  { r: -0.7,    i:  0.27015,name: 'spiral' },
  { r:  0.45,   i:  0.1428, name: 'coral' },
  { r: -1.476,  i:  0,      name: 'airplane' },
  { r: -0.12,   i: -0.77,   name: 'siegel disk' },
];
let presetIdx = 0;

const MAX_ITER = 120;
const ESCAPE   = 4;

// Smooth HSL color from iteration count
function iterToColor(iter, z2) {
  if (iter >= MAX_ITER) return [5, 5, 12, 255];
  // Smooth coloring
  const smooth = iter + 1 - Math.log2(Math.log2(Math.sqrt(z2)));
  const t = smooth / MAX_ITER;
  // Vivid twilight palette: deep blue → violet → orange → white
  const h = (220 + t * 280) % 360;
  const s = 0.85;
  const l = 0.1 + t * 0.55;
  return hslToRgb(h / 360, s, l);
}

function hslToRgb(h, s, l) {
  let r, g, b;
  if (s === 0) { r = g = b = l; }
  else {
    const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
    const p = 2 * l - q;
    r = hue2rgb(p, q, h + 1/3);
    g = hue2rgb(p, q, h);
    b = hue2rgb(p, q, h - 1/3);
  }
  return [r * 255 | 0, g * 255 | 0, b * 255 | 0, 255];
}
function hue2rgb(p, q, t) {
  if (t < 0) t += 1; if (t > 1) t -= 1;
  if (t < 1/6) return p + (q-p)*6*t;
  if (t < 1/2) return q;
  if (t < 2/3) return p + (q-p)*(2/3-t)*6;
  return p;
}

// Zoom / center for the complex plane view
// ZOOM = half-height of complex plane visible; x range extends by aspect ratio
const ZOOM   = 2.0;

function renderJulia() {
  const cr = cReal, ci = cImag;
  // Uniform scale per pixel — preserves aspect ratio
  const unitScale = (2 * ZOOM) / RH;

  for (let py = 0; py < RH; py++) {
    const y0 = (py - RH / 2) * unitScale;
    for (let px = 0; px < RW; px++) {
      const x0 = (px - RW / 2) * unitScale;
      let zr = x0, zi = y0;
      let iter = 0, zr2 = 0, zi2 = 0;
      while (iter < MAX_ITER) {
        zr2 = zr * zr; zi2 = zi * zi;
        if (zr2 + zi2 > ESCAPE) break;
        zi = 2 * zr * zi + ci;
        zr = zr2 - zi2 + cr;
        iter++;
      }
      const [r, g, b, a] = iterToColor(iter, zr2 + zi2);
      const idx = (py * RW + px) * 4;
      pixels[idx]   = r; pixels[idx+1] = g;
      pixels[idx+2] = b; pixels[idx+3] = a;
    }
  }
  ctx.putImageData(imgData, 0, 0);
  // CSS image-rendering:pixelated handles upscaling — no drawImage needed
}

function resize() {
  dpr = Math.min(window.devicePixelRatio || 1, 2);
  W = window.innerWidth; H = window.innerHeight;
  // Render at 0.5× to 0.65× resolution for speed
  const scale = window.innerWidth < 600 ? 0.45 : 0.55;
  RW = Math.ceil(W * scale); RH = Math.ceil(H * scale);
  canvas.width  = RW; canvas.height = RH;
  canvas.style.width  = W + 'px'; canvas.style.height = H + 'px';
  imgData = ctx.createImageData(RW, RH);
  pixels  = imgData.data;
  dirty = true;
}

// Render loop — re-render whenever dirty, handles mid-render resize
let renderPending = false;
function scheduleRender() {
  if (renderPending) return;
  renderPending = true;
  requestAnimationFrame(() => {
    renderPending = false;
    if (dirty) {
      dirty = false;
      renderJulia();
      // If a resize happened during render, dirty is set again — re-schedule
      if (dirty) scheduleRender();
    }
  });
}

// Mouse / touch → update c
function setC(clientX, clientY) {
  if (locked) return;
  // Map mouse position to c range [−1.5, 1.5] × [−1, 1]
  cReal = ((clientX / W) * 2 - 1) * 1.5;
  cImag = ((clientY / H) * 2 - 1) * -1.2;
  paramsEl.textContent = `c = ${cReal.toFixed(4)} + ${cImag.toFixed(4)}i`;
  dirty = true;
  scheduleRender();
}

function toggleLock(clientX, clientY) {
  locked = !locked;
  if (locked) {
    hintEl.textContent = 'locked · click to cycle presets';
  } else {
    hintEl.textContent = 'move mouse to steer c · click to lock';
  }
}

function cyclePreset() {
  presetIdx = (presetIdx + 1) % PRESETS.length;
  const p = PRESETS[presetIdx];
  cReal = p.r; cImag = p.i;
  paramsEl.textContent = `c = ${cReal.toFixed(4)} + ${cImag.toFixed(4)}i  [${p.name}]`;
  hintEl.textContent = `${p.name} · click to advance`;
  dirty = true;
  scheduleRender();
}

canvas.addEventListener('mousemove', e => setC(e.clientX, e.clientY));
canvas.addEventListener('click', () => {
  if (!locked) { toggleLock(); }
  else { cyclePreset(); }
});
canvas.addEventListener('touchmove', e => {
  e.preventDefault();
  if (e.touches.length === 1) setC(e.touches[0].clientX, e.touches[0].clientY);
}, { passive: false });
canvas.addEventListener('touchstart', e => {
  e.preventDefault();
  if (!locked) { toggleLock(); }
  else { cyclePreset(); }
}, { passive: false });

window.addEventListener('resize', () => { resize(); scheduleRender(); });
if (window.visualViewport) {
  window.visualViewport.addEventListener('resize', () => { resize(); scheduleRender(); });
}
window.addEventListener('orientationchange', () => { setTimeout(() => { resize(); scheduleRender(); }, 200); });

resize();
scheduleRender();
</script>
</body>
</html>