let k = 2;

let t = 0;

let j = 0;

let graphEl = [];

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  //Center

  translate(width / 2, height / 2);

  scale(1, -1);

  stroke('black');

  strokeWeight(1);

  line(0, height/2, 0, -height/2);

  line(width/2, 0, -width/2, 0);

  strokeWeight(2);

  noFill();

  beginShape();

  let i = 0;

  let sumX = 0;

  let sumY = 0;

  let ctr = 0;

  for(let t = 0; t < 3*TWO_PI; t+=0.01) {

    i += j;

    let x = (2*cos(k*t) + cos(2*k*t) + cos(3*k*t)) * r * cos(i);

    let y = (2*cos(k*t)+ cos(2*k*t)+ cos(3*k*t)) * r * sin(i);

    vertex(x,y);

    sumX += x;

    sumY += y;

    ++ctr;

  }

  endShape();

  // Center of Mass

  let massX = sumX/ctr;

  let massY = sumY/ctr;

  graphEl.push([massX,massY]);

  strokeWeight(3);

  stroke('red');

  point(massX,massY);

  // Plot in time

  strokeWeight(2);

  noFill();

  beginShape();

  for(let i = 0; i < graphEl.length; ++i) {

    vertex(i/5-width/2+10, graphEl[i][0]+height/4);

  }

  endShape();

  stroke('blue');

  beginShape();

  for(let i = 0; i < graphEl.length; ++i) {

    vertex(i/5-width/2+10, graphEl[i][1]+height/4);

  }

  endShape();

  j += 0.00005;

}