let yPos;

​

function setup() {

  createCanvas(800, 600);

  xPos = random(0, width);

  yPos = random(0, height);

}

​

function draw() {

  background(220);

  let value = frameCount % 255;

  let red = value;

  let green = 100; 

  let blue = 100;

  fill(red, green, blue);

  circle(width/2, height/2, 200);

}