Adding some of my favorite toys

1 files changed, 136 insertions, 0 deletions

diff --git a/src/toys/julia/julia.js b/src/toys/julia/julia.js
new file mode 100644
index 0000000..7727d48
--- /dev/null
+++ b/src/toys/julia/julia.js
@@ -0,0 +1,136 @@
+const MIN_ZOOM = 0.0001;
+const MAX_ZOOM = 4;
+const C_THRESHOLD = Math.sqrt(2)/2;
+const SLIDER_DIV = 2000*C_THRESHOLD;
+
+const gpu = new GPUX();
+const buildRender = (width, height) => gpu.createKernel(function (maxIterations, cr, ci, centerX, centerY, zoom, colorMultipliers) {
+  let zx = (this.output.x / this.output.y) * (centerX + (4 * this.thread.x / this.output.x - 2) * (zoom / 4));
+  let zy = centerY + (4 * this.thread.y / this.output.y - 2) * (zoom / 4);
+  let iterations = 0;
+  for (let i = 0; i < maxIterations; i++) {
+    const xtemp = zx * zx - zy * zy + cr;
+    zy = 2 * zx * zy + ci;
+    zx = xtemp;
+    if (zx * zx + zy * zy > 4) {
+      iterations = i;
+      break;
+    }
+  }
+  if (iterations == 0 || iterations == maxIterations) {
+    this.color(0, 0, 0);
+  } else {
+    this.color(colorMultipliers[0] * iterations, colorMultipliers[1] * iterations, colorMultipliers[2] * iterations);
+  }
+}, { output: [width, height], graphical: true });
+
+const canvasHolder = document.getElementById('canvasHolder');
+let render; // The GPU kernel built from buildRender
+let state = {
+  colorMultipliers: [0.01 * Math.random() + 0.015, 0.03 * Math.random() + 0.007, 0.02 * Math.random() + 0.010],
+  changes: {
+    centerX: 0,
+    centerY: 0,
+    zoom: 3,
+    cr: parseFloat(document.getElementById('realSlider').value) / SLIDER_DIV,
+    ci: parseFloat(document.getElementById('imaginarySlider').value) / SLIDER_DIV,
+    maxIterations: 1000,
+    width: document.body.clientWidth,
+    height: document.body.clientHeight,
+  },
+};
+
+const doRender = (renderF, state) => {
+  // gpu.js doesn't support JS objects as kernel parameters - https://github.com/gpujs/gpu.js/issues/245
+  renderF(state.maxIterations, state.cr, state.ci, state.centerX, state.centerY, state.zoom, state.colorMultipliers);
+};
+
+const loop = () => {
+  const stateChanges = Object.keys(state.changes);
+  if (stateChanges.length > 0) {
+    state = {...state, ...state.changes};
+    if (state.changes.width || state.changes.height) {
+      render = buildRender(state.width, state.height);
+      canvasHolder.appendChild(render.canvas);
+    }
+    if (typeof state.changes.ci !== 'undefined') {
+      document.getElementById('imag-val').value = state.ci.toFixed(4);
+      document.getElementById('imaginarySlider').value = state.changes.ci * SLIDER_DIV;
+    }
+    if (typeof state.changes.cr !== 'undefined') {
+      document.getElementById('real-val').value = state.cr.toFixed(4);
+      document.getElementById('realSlider').value = state.changes.cr * SLIDER_DIV;
+    }
+    state.changes = {};
+    doRender(render, state);
+  }
+
+  requestAnimationFrame(loop);
+};
+
+loop();
+
+// UI Code
+
+const startAnim = (sliderId, complexComponentName='ci') => {
+  const restart = (interval) => {
+    clearInterval(interval);
+    document.getElementById(sliderId).innerHTML = 'Animate';
+    document.getElementById(sliderId).onclick = ()=>startAnim(sliderId, complexComponentName);
+    return;
+  };
+  const start = setInterval(() => {
+    if (state[complexComponentName] >= C_THRESHOLD) {
+      restart(start);
+    }
+
+    state.changes[complexComponentName] = state[complexComponentName] + 0.001;
+  }, 1000/60);
+  document.getElementById(sliderId).innerHTML = 'Stop';
+  document.getElementById(sliderId).onclick = ()=>restart(start);
+};
+
+document.getElementById('imaginarySlider').oninput = function() {
+  state.changes.ci = parseFloat(this.value) / SLIDER_DIV;
+};
+document.getElementById('realSlider').oninput = function() {
+  state.changes.cr = parseFloat(this.value) / SLIDER_DIV;
+};
+
+document.getElementById('imag-val').addEventListener('change', function (e) {
+  state.changes.ci = parseFloat(this.value);
+});
+document.getElementById('real-val').addEventListener('change', function (e) {
+  state.changes.cr = parseFloat(this.value);
+});
+
+canvasHolder.addEventListener('wheel', (e) => {
+  e.preventDefault();
+  state.changes.zoom = Math.min(Math.max(state.zoom + e.deltaY * 0.001 * state.zoom, MIN_ZOOM), MAX_ZOOM);
+});
+
+let isDown = false;
+canvasHolder.addEventListener('mousedown', (e) => {
+  e.preventDefault();
+  isDown = true;
+}, true);
+
+canvasHolder.addEventListener('mouseup', (e) => {
+  e.preventDefault();
+  isDown = false;
+}, true);
+
+canvasHolder.addEventListener('mousemove', (e) => {
+  e.preventDefault();
+  if (isDown) {
+    let deltaX = -e.movementX * state.zoom / document.body.clientWidth;
+    let deltaY = e.movementY * state.zoom / document.body.clientHeight;
+    state.changes.centerX = state.centerX + deltaX;
+    state.changes.centerY = state.centerY + deltaY;
+  }
+}, true);
+
+window.addEventListener('resize', () => {
+  state.changes.width = document.body.clientWidth;
+  state.changes.height = document.body.clientHeight;
+});