class ResourceField extends Field
{
  ResourceField(int max_dimension)
  {
    super(max_dimension);
  }
  
  void update()
  {
    super.update();
    
    //remove all emitters that have a 0 or less emission value
    Emitter e;
    for(int i = 0; i < emitters.size(); i++)
    {
      e = (Emitter) emitters.get(i);      
      if (e.getEmissionValue() < 1)
      {
        emitters.remove(i);
        i--;
      }
    }
  }
}