// https://en.wikipedia.org/wiki/Archimedean_spiral

​

let slider;

​

function setup(){

  createCanvas(400, 400);

  // background(0);

  angleMode(DEGREES);

  slider = createSlider(-10, 10, 0.5, 0.01);  

}

​

function draw() {

  background(50);

  let a = 1.5;

  let b = slider.value();

  stroke(255);

  noFill();

  translate(width/2, height/2);

  beginShape();

    for (let i = 0; i < 360*2; i ++) {

      //let t = seq(0,5*pi, length.out=500);

      let x = (a + b*i) * cos(i);

      let y = (a + b*i) * sin(i);

      vertex(x, y);

    }

  endShape();

}