### Tesselation #1

Tesselation. Based on work by Åse Balko: instagram.com/asebalko/

#tesselation #simplex #noise #asebalko

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```// Tesselation #1. Created by Reinder Nijhoff 2021 - @reindernijhoff
//
// https://turtletoy.net/turtle/6e4e06d42e
//

const seed = 1; // min=1, max=100, step=1
const segments = 70; // min=10, max=200, step=1
const innerRadius = 25; // min=10, max=100, step=0.1
const ringWidth = 3; // min=1, max=20, step=0.1
const ringWidthPow = 1.05; // min=1, max=1.5, step=0.01
const noiseAmplitude = 5; // min=0, max=20, step=0.1
const noiseFreq = 0.0175; // min=0, max=0.2, step=0.001
const noiseFallOffPow = 0.5; // min=0.1, max=2, step=0.01

const turtle = new Turtle();
const noise1 = new SimplexNoise(seed);
const noise2 = new SimplexNoise(seed+1);

const lines = Math.ceil(200 / ringWidth);
const da = Math.PI * 2 / segments;

function point(a, i) {
const radius =  Math.pow(i, ringWidthPow) * ringWidth + innerRadius;
const p = [Math.cos(a) * radius, Math.sin(a) * radius];
p[0] += noise1.noise2D([p[0]*noiseFreq, p[1]*noiseFreq]) * noiseAmplitude * Math.pow(2-Math.sqrt(p[0]**2 + p[1]**2)/500, noiseFallOffPow);
p[1] += noise2.noise2D([p[0]*noiseFreq, p[1]*noiseFreq]) * noiseAmplitude * Math.pow(2-Math.sqrt(p[0]**2 + p[1]**2)/500, noiseFallOffPow);
return p;
}

function triangleLines(p0, p1, p2, p3) {
turtle.jump(p2);
turtle.goto(p0);
turtle.goto(p1);
turtle.jump(p0);
turtle.goto(p3);
}

function walk(i) {
for (let s = 0; s<segments; s++) {
const a0 = -(i / 2) * da / 2 + da * s;
const a1 = -((i+1) / 2) * da / 2 + da * s;

triangleLines(point(a0, i), point(a0+da, i), point(a1, i+1), point(a1+da, i+1));
}
return i < lines;
}

////////////////////////////////////////////////////////////////
// Simplex Noise utility code. Created by Reinder Nijhoff 2020
// https://turtletoy.net/turtle/6e4e06d42e
// Based on: http://webstaff.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
////////////////////////////////////////////////////////////////
function SimplexNoise(seed = 1) {
const grad = [  [1, 1, 0], [-1, 1, 0], [1, -1, 0], [-1, -1, 0],
[1, 0, 1], [-1, 0, 1], [1, 0, -1], [-1, 0, -1],
[0, 1, 1], [0, -1, 1], [0, 1, -1], [0, -1, -1] ];
const perm = new Uint8Array(512);

const F2 = (Math.sqrt(3) - 1) / 2, F3 = 1/3;
const G2 = (3 - Math.sqrt(3)) / 6, G3 = 1/6;

const dot2 = (a, b) => a[0] * b[0] + a[1] * b[1];
const sub2 = (a, b) => [a[0] - b[0], a[1] - b[1]];
const dot3 = (a, b) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
const sub3 = (a, b) => [a[0] - b[0], a[1] - b[1], a[2] - b[2]];

class SimplexNoise {
constructor(seed = 1) {
for (let i = 0; i < 512; i++) {
perm[i] = i & 255;
}
for (let i = 0; i < 255; i++) {
const r = (seed = this.hash(i+seed)) % (256 - i)  + i;
const swp = perm[i];
perm[i + 256] = perm[i] = perm[r];
perm[r + 256] = perm[r] = swp;
}
}
noise2D(p) {
const s = dot2(p, [F2, F2]);
const c = [Math.floor(p[0] + s), Math.floor(p[1] + s)];
const i = c[0] & 255, j = c[1] & 255;
const t = dot2(c, [G2, G2]);

const p0 = sub2(p, sub2(c, [t, t]));
const o  = p0[0] > p0[1] ? [1, 0] : [0, 1];
const p1 = sub2(sub2(p0, o), [-G2, -G2]);
const p2 = sub2(p0, [1-2*G2, 1-2*G2]);

let n =  Math.max(0, 0.5-dot2(p0, p0))**4 * dot2(grad[perm[i+perm[j]] % 12], p0);
n += Math.max(0, 0.5-dot2(p1, p1))**4 * dot2(grad[perm[i+o[0]+perm[j+o[1]]] % 12], p1);
n += Math.max(0, 0.5-dot2(p2, p2))**4 * dot2(grad[perm[i+1+perm[j+1]] % 12], p2);

return 70 * n;
}
hash(i) {
i = 1103515245 * ((i >> 1) ^ i);
const h32 = 1103515245 * (i ^ (i>>3));
return h32 ^ (h32 >> 16);
}
}
return new SimplexNoise(seed);
}```