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2020-coding-projects/mandelbrot/worker.js

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2020-04-26 13:40:03 +00:00
function calcRe(col) {
return (col * (maxX - minX)) / width + minX;
}
function calcIm(row) {
return (row * (maxY - minY)) / height + minY;
}
function hslToRgb(h, s, l) {
var r, g, b;
if (s == 0) {
r = g = b = l; // achromatic
} else {
var hue2rgb = 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;
};
var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
var p = 2 * l - q;
r = hue2rgb(p, q, h + 1 / 3);
g = hue2rgb(p, q, h);
b = hue2rgb(p, q, h - 1 / 3);
}
return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)];
}
function getColor(iterations, maxIterations) {
const rgb = hslToRgb(iterations / 256, 1, iterations / (iterations + 8));
return [...rgb, 255];
}
function setPixel(set, width, x, y, color) {
const startIndex = y * width * 4 + x * 4;
set[startIndex + 0] = color[0];
set[startIndex + 1] = color[1];
set[startIndex + 2] = color[2];
set[startIndex + 3] = color[3];
return set;
}
async function getMandelbrotSet(maxIter, minX, minY, maxX, maxY, width, height) {
let partSet = [];
for (let i = 0; i < width * height * 4; i++) {
partSet.push(0);
}
for (let row = 0; row < height; row++) {
for (let col = 0; col < width; col++) {
const c_re = (col * (maxX - minX)) / width + minX;
const c_im = (row * (maxY - minY)) / height + minY;
let x = 0,
y = 0;
let iteration = 0;
for (; x ** 2 + y ** 2 <= 4 && iteration < maxIter; iteration++) {
const x_new = x * x - y * y + c_re;
y = 2 * x * y + c_im;
x = x_new;
}
partSet = setPixel(partSet, width, col, row, getColor(iteration, maxIter));
}
}
return partSet;
}
async function loadMandelbrotSet(resolution, minX, minY, maxX, maxY, width, height) {
return new Promise((resolve, reject) => {
const xhr = new XMLHttpRequest();
xhr.open('GET', `http://127.0.0.1:8001?minX=${minX}&maxX=${maxX}&minY=${minY}&maxY=${maxY}&width=${width}&height=${height}`, true)
xhr.send();
xhr.addEventListener('readystatechange', (e) => {
if (xhr.readyState == 4) {
const response = JSON.parse(xhr.responseText);
console.log(response);
resolve(response);
}
}, false);
});
}
async function getForResolution(resolution = 1000) {
const chunks = 4;
const chunkWidth = Math.round(width / chunks);
const chunkHeight = Math.round(height / chunks);
const dx = (maxX - minX) / chunks;
const dy = (maxY - minY) / chunks;
const promises = [];
for (let i = 0; i < chunks; i++) {
for (let j = 0; j < chunks; j++) {
promises.push(new Promise((resolve, reject) => {
const x = i;
const y = j;
loadMandelbrotSet(resolution,
minX + x * dx,
minY + y * dy,
minX + (x + 1) * dx,
minY + (y + 1) * dy,
chunkWidth,
chunkHeight
).then(partSet => {
console.log('finished', x, y);
const startRow = y * chunkHeight;
const startCol = x * chunkWidth;
console.log(startRow, startCol, chunkHeight, chunkWidth);
for (let row = 0; row < chunkHeight; row++) {
for (let col = 0; col < chunkWidth; col++) {
for (let i = 0; i < 4; i++) {
mandelbrot.data[(row + startRow) * width * 4 + (startCol + col) * 4 + i] = partSet[row * chunkWidth * 4 + col * 4 + i];
}
}
}
sendMandelbrot();
resolve();
});
}));
}
}
await Promise.all(promises);
}
let mandelbrot;
let width,
height;
let minX,
maxX,
minY,
maxY;
onmessage = function (e) {
const data = e.data[0];
mandelbrot = data.mandelbrot;
width = data.width;
height = data.height;
minX = data.minX;
minY = data.minY;
maxX = data.maxX;
maxY = data.maxY;
getForResolution();
};
function sendMandelbrot() {
postMessage([mandelbrot]);
}