const x0 = 0,

    y0 = 0,

    r0 = 1,

    b0 = -1 / r0;

  const x1 = (1 + t) / 2,

    y1 = 0,

    r1 = r0 - Math.sqrt(x1 * x1 + y1 * y1),

    b1 = 1 / r1;

  const x2 = -r1,

    y2 = y1,

    r2 = x1,

    b2 = 1 / r2;

  const c0 = [x0, x0, b0];

  const c1 = [x1, y1, b1];

  const c2 = [x2, y2, b2];

  const b3 = solve(b0, b1, b2);

  const c3 = [

    solve(b0 * x0, b1 * x1, b2 * x2, 2) / b3,

    solve(b0 * y0, b1 * y1, b2 * y2, 2) / b3,

    b3

  ];

  return [

    c0, c1, c2, c3,

    ...circles(c0, c1, c2, c3),

    ...circles(c3, c1, c2, c0),

    ...circles(c0, c2, c3, c1),

    ...circles(c0, c1, c3, c2)

  ];

}

​

function* circles(c0, c1, c2, c3) {

  const c = innerSoddy(c0, c1, c2, c3);

  if (Math.abs(c[2]) > 200)

    return;

  yield c;

  yield* circles(c0, c1, c, c2);

  yield* circles(c1, c, c2, c0);

  yield* circles(c2, c, c0, c1);

}

​

function innerSoddy([x0, y0, b0], [x1, y1, b1], [x2, y2, b2], [x3, y3, b3]) {

  const b = 2 * (b0 + b1 + b2) - b3;

  return [

    (2 * (b0 * x0 + b1 * x1 + b2 * x2) - b3 * x3) / b,

    (2 * (b0 * y0 + b1 * y1 + b2 * y2) - b3 * y3) / b,

    b

  ];

}

​

function solve(x, y, z, offset = 0) {

  const b = x + y + z;

  const c = x * x + y * y + z * z - b * b / 2 - offset;

  return Math.sqrt(Math.max(0, b * b - 2 * c)) + b;

}

​

const dim = 400

const half = dim / 2

​

function setup() {

  createCanvas(dim, dim);

  scale(dim / 2)

}

​

function draw() {

  background(255);

  translate(dim / 2, dim / 2)

  noFill()

  const factor = dim / 2.1

  for (const [x, y, c] of gasket(0)) {

    const r = Math.abs(1 / c);

    circle(x * factor, y * factor, r * factor * 2);

  }

  noLoop()

}