Visualization toolmaker. Founder @observablehq. Creator @d3. Former @nytgraphics. Pronounced BOSS-tock.
canvas = {
const perlin = new Noise(3);
const context = DOM.context2d(width, height);
context.canvas.style.background = "#000";
context.lineWidth = 0.5;
context.globalAlpha = 0.05;
for (let px = 0; px < width; ++px) {
for (let i = 0; i < height / 6; ++i) {
let x = px;
let y = Math.random() * height;
let n = perlin.noise(x * period, y * period);
context.strokeStyle = `hsl(${-210 + n * 600}, 100%, ${800 * n * n * n}%)`;
context.beginPath();
context.moveTo(x, y);
for (let m = 0; m < length && y >= 0 && y <= height; ++m) {
n = perlin.noise(x * period, y * period);
context.lineTo(x += Math.cos(n * 14), y += Math.sin(n * 14));
}
context.stroke();
}
yield context.canvas;
}
}
period = 0.01
class Noise {
static lerp(t, a, b) {
return a + t * (b - a);
}
static grad2d(i, x, y) {
const v = (i & 1) === 0 ? x : y;
return (i & 2) === 0 ? -v : v;
}
constructor(octaves = 1) {
this.p = new Uint8Array(512);
this.octaves = octaves;
this.init();
}
init() {
for (let i = 0; i < 512; ++i) {
this.p[i] = Math.random() * 256;
}
}
noise2d(x2d, y2d) {
const X = Math.floor(x2d) & 255;
const Y = Math.floor(y2d) & 255;
const x = x2d - Math.floor(x2d);
const y = y2d - Math.floor(y2d);
const fx = (3 - 2 * x) * x * x;
const fy = (3 - 2 * y) * y * y;
const p0 = this.p[X] + Y;
const p1 = this.p[X + 1] + Y;
return Noise.lerp(
fy,
Noise.lerp(
fx,
Noise.grad2d(this.p[p0], x, y),
Noise.grad2d(this.p[p1], x - 1, y)
),
Noise.lerp(
fx,
Noise.grad2d(this.p[p0 + 1], x, y - 1),
Noise.grad2d(this.p[p1 + 1], x - 1, y - 1)
)
);
}
noise(x, y) {
let e = 1,
k = 1,
s = 0;
for (let i = 0; i < this.octaves; ++i) {
e *= 0.5;
s += e * (1 + this.noise2d(k * x, k * y)) / 2;
k *= 2;
}
return s;
}
}
height = 600
length = 400
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