class ResourceEmitter extends Emitter
{
  float growth_rate;
  float max_ev; //maximum emission value;
  
  ResourceEmitter(Tuple position, String et, float ev, float growth_rate, float max_ev)
  {
    super(position, et, ev);
    this.growth_rate = growth_rate;
    this.max_ev = max_ev;
  }
  
  void setMaxGrowthRate(float max_ev)
  {
    this.max_ev = max_ev;
  }
  
  void update()
  {
    float time_elapsed = ((millis() - last_update_millis) / 1000);
    super.update();
    ev += growth_rate * time_elapsed;
    if (ev > max_ev)
    {
      ev = max_ev;
    }
  }
}