let spirals = []; // global array variable

let totalSpirals = 10; //start wtih 10 spirls.

// The Spiral class draws shapes along an outward spiral path

class Spiral {

  constructor(xpos, ypos) {

    // Center of the spiral

    this.cx = xpos;

    this.cy = ypos;

    // Starting angle and radius

    this.angle = random(TWO_PI);

    this.radius = 0; // begins with a zero radius

    this.rotationSpeed = random(0.05, 0.2); // speed of the spiral

    this.radiusIncrement = random(1, 3); // increases the cirlce radius

    this.shapeDim = random(10, 30); // size of each circe

    this.r = floor(random(255)); // random color assigned

    this.g = floor(random(255));

    this.b = floor(random(255));

  }

  update() {

    this.angle += this.rotationSpeed;

    this.radius += this.radiusIncrement;

    //math formula to calculate the circular movement

    let x = this.cx + this.radius * cos(this.angle);

    let y = this.cy + this.radius * sin(this.angle);

    if (x < 0 || x > width || y < 0 || y > height) {

      this.radius = 0;

      this.cx = random(width); // when circle moves.  out of the scren,

                              // randomly place it 

      this.cy = random(height);

    }

  }

  display() {

    let x = this.cx + this.radius * cos(this.angle);

    let y = this.cy + this.radius * sin(this.angle);

    noStroke();

    fill(this.r, this.g, this.b);

      circle(x, y, this.shapeDim); // drawing circle

  }

}

​

function setup() {

  createCanvas(550, 550);

  background(0);

  //start of with 10 spiralss and randomly place them.

  for (let i = 0; i < totalSpirals; i++) {

    let cx = random(width);

    let cy = random(height);

    spirals.push(new Spiral(cx, cy));

  }

}

​

function draw() {

  background(0);

  // Update and display each spiral in the array

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

    spirals[i].update();

    spirals[i].display();

  }

}

​

//upon mouse click, create 5 neew circles/spirals object and push into array

function mouseClicked() {

  for (let i = 0; i < 5; i++) {

    let cx = random(width);

    let cy = random(height);

    spirals.push(new Spiral(cx, cy));

  }

}

​