// Learning Processing
// Daniel Shiffman
// http://www.learningprocessing.com

// Example 23-2: Simple particle system with ArrayList

ArrayList particles;

void setup() {
  size(200,200);
  particles = new ArrayList();
  smooth();
}

void draw() {
  // A new Particle object is added to the ArrayList every cycle through draw().
  particles.add(new Particle()); 

  background(255);
  // Iterate through our ArrayList and get each Particle
  // The ArrayList keeps track of the total number of particles.
  for (int i = 0; i < particles.size(); i++ ) { 
    Particle p = (Particle) particles.get(i);
    p.run();
    p.gravity();
    p.display();
  }

  // If the ArrayList has more than 100 elements in it, we delete the first element, using remove().
  if (particles.size() > 100) {
    particles.remove(0); 
  }
}