ArrayList<Particle> particles;
Attractor attractor;

void setup() {
  size(400,400);
  frameRate(30);

  particles = new ArrayList<Particle>();
  attractor = new Attractor();
}

void draw() {
  smooth();
  noStroke();
  background(50,50);
 
  //PARTICLES ACT MORE AS A "SCHOOL" WITH FORCES CALLED BEFORE ITERATOR
  //(RANDOM VALUE SET ONCE) 
  //PVector wind = new PVector(random(-.1,.1),random(-0.3,0.1));
  //PVector gravity = new PVector(0,0.1);

  particles.add(new Particle());
  applyAttractor(attractor);
  
  //attractor.display();

  //Iterator: an object that knows how to iterate

  Iterator<Particle> it = particles.iterator();
   while (it.hasNext()) {
   Particle p = it.next();
 
 //PARTICLES ACT MORE INDEPENDENTLY WITH FORCES CALLED WITHIN ITERATOR  
   PVector wind = new PVector(random(-.1,.3),random(-0.3,0.1));
   PVector gravity = new PVector(0,0.1);
    
   // p.run(); //IMPLEMENT THIS FUNCTION WITH PARTICLE SYSTEM
   p.applyForce(wind);
   //p.applyForce(gravity);
   p.update();
   p.display();
 
   //Remove particles no longer necessary:   
   if (p.isDead()) {
     it.remove();
   }

  //Single Particle:
  /*
   particle.applyForce(wind);
   particle.applyForce(gravity);
   particle.update();
   particle.display();
   //particle.checkEdges(); //MOVED INTO DISPLAY
   */
   
  }
}

void applyAttractor(Attractor a) {
  for (Particle p: particles) { 
    //Syntax for calling a method external to the class 
    //for each instance in arrayList
    PVector attract = a.attract(p);
    p.applyForce(attract);
  }
}