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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 GPU();
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;
});
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