let factor = 0;

​

function setup() {

  createCanvas(windowWidth - 20, windowHeight - 20);

  r = height / 2 - 16;

}

​

function getVector(index, total) {

  const angle = map(index, 0, total, 0, TWO_PI);

  const v = p5.Vector.fromAngle(angle + PI);

  v.mult(r);

  v.angle = angle;

  return v;

}

​

function draw() {

  background(0);

  colorMode(HSB);

  const total = 200; //int(map(mouseX, 0, width, 0, 200));

  factor += 0.015;

​

  translate(width / 2, height / 2);

  stroke(255, 150);

  strokeWeight(2);

  noFill();

  ellipse(0, 0, r * 2);

​

  strokeWeight(2);

  for (let i = 0; i < total; i++) {

    const a = getVector(i, total);

    const b = getVector(i * factor, total);

    const hue = map(b.angle, 0, TWO_PI, 0, 255);

    fill(hue, 255, 255);

    line(a.x, a.y, b.x, b.y);

  }

}