​

function setup() {

  createCanvas(400, 400);

  frameRate(30);

  pixelDensity(1);

  createLoop({

    duration: 3, gif: true});

}

​

//------------------------------------------

function draw() {

  background("DodgerBlue");

  fill("white");

  noStroke();

​

rectMode(CENTER);

  angle = animLoop.theta;

  let r = map(sin(angle), -1, 1, 0, 100);

  rect(200, 200, 200, 200, r);

}