image = {
const context = DOM.context2d(width, height);
const worker = new Worker(script);
function messaged({data: points}) {
context.fillStyle = "#fc923a";
context.fillRect(0, 0, width, height);
context.beginPath();
for (let i = 0, n = points.length; i < n; i += 2) {
const x = points[i], y = points[i + 1];
context.moveTo(x + 1.5, y);
context.arc(x, y, 1.5, 0, 2 * Math.PI);
}
context.fillStyle = "#803c05";
context.fill();
}
invalidation.then(() => worker.terminate());
worker.addEventListener("message", messaged);
worker.postMessage({data, width, height, n});
return context.canvas;
}
script = {
const blob = new Blob([`
importScripts("${await require.resolve("d3-delaunay@^5.1.1")}");
onmessage = event => {
const {data: {data, width, height, n}} = event;
const points = new Float64Array(n * 2);
const c = new Float64Array(n * 2);
const s = new Float64Array(n);
// Initialize the points using rejection sampling.
for (let i = 0; i < n; ++i) {
for (let j = 0; j < 30; ++j) {
const x = points[i * 2] = Math.floor(Math.random() * width);
const y = points[i * 2 + 1] = Math.floor(Math.random() * height);
if (Math.random() < data[y * width + x]) break;
}
}
const delaunay = new d3.Delaunay(points);
const voronoi = delaunay.voronoi([0, 0, width, height]);
for (let k = 0; k < 80; ++k) {
// Compute the weighted centroid for each Voronoi cell.
c.fill(0);
s.fill(0);
for (let y = 0, i = 0; y < height; ++y) {
for (let x = 0; x < width; ++x) {
const w = data[y * width + x];
i = delaunay.find(x + 0.5, y + 0.5, i);
s[i] += w;
c[i * 2] += w * (x + 0.5);
c[i * 2 + 1] += w * (y + 0.5);
}
}
// Relax the diagram by moving points to the weighted centroid.
// Wiggle the points a little bit so they don’t get stuck.
const w = Math.pow(k + 1, -0.8) * 10;
for (let i = 0; i < n; ++i) {
const x0 = points[i * 2], y0 = points[i * 2 + 1];
const x1 = s[i] ? c[i * 2] / s[i] : x0, y1 = s[i] ? c[i * 2 + 1] / s[i] : y0;
points[i * 2] = x0 + (x1 - x0) * 1.8 + (Math.random() - 0.5) * w;
points[i * 2 + 1] = y0 + (y1 - y0) * 1.8 + (Math.random() - 0.5) * w;
}
postMessage(points);
voronoi.update();
}
close();
};
`], {type: "text/javascript"});
const script = URL.createObjectURL(blob);
invalidation.then(() => URL.revokeObjectURL(script));
return script;
}
data = {
const image = await FileAttachment("Screen Shot 2020-09-14 at 9.14.49 PM.png").image();
const height = Math.round(width * image.height / image.width);
const context = DOM.context2d(width, height, 1);
context.drawImage(image, 0, 0, image.width, image.height, 0, 0, width, height);
const {data: rgba} = context.getImageData(0, 0, width, height);
const data = new Float64Array(width * height);
for (let i = 0, n = rgba.length / 4; i < n; ++i) data[i] = Math.max(0, 1 - rgba[i * 4] / 254);
data.width = width;
data.height = height;
return data;
}
n = Math.round(width * height / 40)
height = data.height
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