let count = 1;

​

let num_of_stars = 200;

​

// co-ordinates of the center from where the stars will trace a circle

let center_x, center_y;

​

// will contain all the star objects.

let all_stars = [];

​

function setup() {

  createCanvas(700, 700);

  background(0);

  // centering the stars on the geometric center of the canvas

  center_x = width/2;

  center_y = height/2;

  // creating stars and appending it to the array

  let i = 0;

  while (i < num_of_stars) {

    all_stars[i] = new Star();

    i++;

  }

  // always start the trace with yellow.

  fill("yellow");

}

​

function draw() {

  // modifying the attributes of each star, one at a time

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

    let current_star = all_stars[i];

    // tracing a circle from center using the radius and the cosine and sine function

    current_star.xpos = center_x + current_star.radius * cos(current_star.angle);

    current_star.ypos = center_y + current_star.radius * sin(current_star.angle);

    // displaying the star onto the canvas

    current_star.show();

    // varying the angle to trace a circle

    current_star.angle += 0.01;

  }

  // incrementing count which is used in changing the color of the stars.

  count += 0.5;

}

​

class Star {

  constructor() {

    // each star will have a random distance from the center

    this.radius = random(width);

    // each star has a random co-ordinate relative to the center

    this.xpos = center_x + random(-this.radius, this.radius);

    this.ypos = center_y + random(-this.radius, this.radius);

    // Calculating the angle of the star relative to the center.

    // A random constant is multiplied because without it the stars seems to only assume angle between -90 and 90 degrees. Try running the draw() function without this constant only once.

    this.angle = atan((center_y - this.ypos)/(center_x - this.xpos))*random(4, 9);

  }

  // function to display the star

  show() {

    noStroke();

    // changing color with respect to the count variable

    if (count % 100 === 0) {

      // restricted the random number to 10, to avoid getting very dark colors.

      fill(color(random(10, 255), random(10, 255), random(100, 255)));

    }

    // star has a random diameter.

    circle(this.xpos, this.ypos, random(1, 3));

  }

}