let c = 4;

let slider;

let sliderValue;

let currValue;

function setup() {

  createCanvas(400, 400);

  slider = createSlider(0, 360, 137.5, 0.5);

  sliderValue = createP('');

  background(0);

  angleMode(DEGREES);

  colorMode(HSB);

}

​

​

function draw() {

  if(currValue != slider.value()){

    background(0);

    n = 0;

  }

  sliderValue.html(slider.value());

  let a = n * slider.value();

  let r = c * sqrt(n);

  let x = r * cos(a) + width/2;

  let y = r * sin(a) + height /2;

  fill(255);

  fill((a-r)%256, 255,255);

  noStroke();

  ellipse(x,y,4,4);

  n++;

  currValue = slider.value();

}