// Convert a polar coordinate (r,theta) to cartesian (x,y):

// x = r * cos(theta)

// y = r * sin(theta)

​

let r;

let theta;

let position;

​

function setup() {

  createCanvas(640, 420);

  // Initialize all values

  r = height * 0.45;

  theta = 0;

}

​

function draw() {

  background(255, 10);

​

  // Translate the origin point to the center of the screen

  translate(width / 2, height / 2);

​

  // // Convert polar to cartesian

  // let x = r * cos(theta);

  // let y = r * sin(theta);

position = p5.vector.fromAngle(theta);

  positon.mult(r);

​

  // Draw the ellipse at the cartesian coordinate

  stroke(0);

  strokeWeight(2);

  noFill();

  circle(0, 0, r * 2);

​

  fill(127);

  line(0, 0, x, y);

  circle(position.x,pos.y, 48);

​

  // Increase the angle over time

  theta += 0.02;

}

​