color c = 256; //palette.get(cz,1); 

// Births particle system, based on
// Daniel Shiffman <http://www.shiffman.net>

class Birth {
  Vector3D loc;
  Vector3D vel;
  Vector3D acc;
  float timer = 100; // NOTE:  better to let them die by location (e.g. x^2,y^2,z^2 < 10,10,10)
  int number = 0;

  
  //The Constructor (called when the object is first created)
  Birth(Vector3D a, Vector3D v, Vector3D l) {
    acc = a.copy();
    vel = v.copy();
    loc = l.copy();
  }

  //main function to operate object)
  void run() {
    update();
    dead();
    render();
  }
  
  //function to update location
  void update() {
    vel.add(acc);
    loc.add(vel);
    timer -= 1.0;
  }
  
  boolean dead() {
    if (timer <= 0.0) {
      return true;
    } else {
      return false;
    }
  }


  //function to display
  void render() {
    pushMatrix();
    rotateX(radians(90));
    rotateZ(radians(181));
    rectMode(CENTER);
    translate(loc.x, loc.y, loc.z);
    //stroke(c);
    //c--;
    point(0,0,0);
    //sphere(1);
    //ellipse(1,1,0.1,0.1);
    popMatrix();
  }

}



/*
     Particle system class
*/

class ParticleSystem {

  ArrayList particles;    // An arraylist for all the particles
  Vector3D acceleration; // = new Vector3D(3,0,0);        // The acceleration vector for particles
  Vector3D velocity;      // The velocity of a particle
  Vector3D origin;        // An origin point for where particles are birthed
  int interval = 7;  // NOTE: it would be better to have this related to the birth-rate, so when you have a lower birth rate, you get a higher interval
  float birthrate;

  ParticleSystem(int num, Vector3D a, Vector3D o, Vector3D v, float br) {
    particles = new ArrayList();              // Initialize the arraylist
    acceleration = a.copy();
    origin = o.copy();                        // Store the origin point
    velocity = v.copy();    // Store the velocity vector
    birthrate = br;
    for (int i = 0; i < num; i++) {
      particles.add(new Birth(acceleration, velocity, origin));    // Add "num" amount of particles to the arraylist
  }
  }

  void run() {
    // Cycle through the ArrayList backwards b/c we are deleting
    for (int i = particles.size()-1; i >= 0; i--) {
      Birth b = (Birth) particles.get(i);
      b.run();
      if (b.dead()) {
        particles.remove(i);
      }
    }
  }

  int iv;
  int particleCounter = 0;
            
  void addParticle() {
    if ((iv % 12) == 0) {
      particles.add(new Birth(acceleration, velocity, origin));
      iv = interval; //(int)birthrate;
      particleCounter++;;
    } else {
      iv++;
    }      
  }
  
}