/** 
 * Simple Particle Emitter 
 * Nick Selvaggio
 * 12.02.09
 **/
class Emitter {

  ArrayList p;         //our emitters particle array. 
  int pnum; 

  PVector loc; 

  Emitter(int nump, PVector location) { 

      p = new ArrayList();

      pnum = nump;    //lol

      loc = location; 

      createParticles(); 

  }

  //lets step through time with this function. 
  void step() {    
    for(int i=0; i<p.size(); i++) {
      Particle particle = (Particle) p.get(i);
      particle.applyForces(forces); 
      particle.render(); 

      live(particle,i);       //just living...
    }  
    
    emit();
  }

  void emit() { 
    //create a random force for each particle in our system. 
    PVector emitForce;
   
    for(int i=0; i<p.size(); i++) {
      emitForce = new PVector(random(-2, 2), random(-2, 2)); 
      
      Particle particle = (Particle) p.get(i);
      
      particle.applyForce(emitForce); 
    }
        
  }

  void createParticles() { 
    
    p = new ArrayList(); 

    for(int i=0; i<pnum; i++) { 
      p.add(new Particle(new PVector(width/2, height/2)));    //not using loc right now. 
    }
  } 

  void live(Particle _p, int i) { 
    if(_p.t > _p.lifespan) { 
      die(_p, i); 
    } 
  }

  void die(Particle _p, int i) { 
    _p.die();
    p.remove(i);  
  }
}