import greenfoot.*;  



| An ant that collects food.
|
| @author Michael Kölling
| @version 1.1
|
public class Ant
extends Creature
{    


| Every how many steps can we place a pheromone drop.
|
private static final int MAX_PH_LEVEL = 18;

    

| How long do we keep direction after finding pheromones.
|
private static final int PH_TIME = 30;

    

| Indicate whether we have any food with us.
|
private boolean carryingFood = false;

    

| How much pheromone do we have right now.
|
private int pheromoneLevel = MAX_PH_LEVEL;

    

| How well do we remember the last pheromone - larger number: more recent
|
private int foundLastPheromone = 0;

    


| Create an ant with a given home hill. The initial speed is zero (not moving).
|
public Ant(AntHill home)
    {
        setHomeHill(home);
    }

    


| Do what an ant's gotta do.
|
public void act()
    {
        if (carryingFood) {
            walkTowardsHome();
            handlePheromoneDrop();
            checkHome();
        }
        else {
            searchForFood();
        }
    }

    


| Walk around in search of food.
|
private void searchForFood()
    {
        if (foundLastPheromone > 0) { 
            foundLastPheromone--;
            walkAwayFromHome();
        }
        else if (smellPheromone()) {
            walkTowardsPheromone();
        }
        else {
            randomWalk();
        }
        checkFood();
    }

    


| Are we home? Drop the food if we are, and start heading back out.
|
private void checkHome()
    {
        if (atHome()) {
            dropFood();
        }
    }

    


| Are we home?
|
private boolean atHome()
    {
        if (getHomeHill() != null) {
            return (Math.abs(getX() - getHomeHill().getX()) < 4) && (Math.abs(getY() - getHomeHill().getY()) < 4);
        }
        else {
            return false;
        } 
    }

    


| Is there any food here where we are? If so, take some!.
|
public void checkFood()
    {
        Food food = (Food) getOneIntersectingObject(Food.class);
        if (food != null) {
            takeFood(food); 
        }
    }

    


| Take some food from a fool pile.
|
private void takeFood(Food food)
    {
        carryingFood = true;
        food.takeSome();
        setImage("ant-with-food.gif");
    }

    


| Drop our food in the ant hill.
|
private void dropFood()
    {
        carryingFood = false;
        getHomeHill().countFood();
        setImage("ant.gif");
    }

    


| Check whether we can drop some pheromone yet. If we can, do it.
|
private void handlePheromoneDrop()
    {
        if (pheromoneLevel == MAX_PH_LEVEL) {
            Pheromone ph = new Pheromone();
            getWorld().addObject(ph, getX(), getY());
            pheromoneLevel = 0;
        }
        else {
            pheromoneLevel++;
        }
    }

    


| Check whether we can smell pheromones. If we can, return true, otherwise return false.
|
public boolean smellPheromone()
    {
        Actor ph = getOneIntersectingObject(Pheromone.class);
        return (ph != null);
    }

    


| If we can smell some pheromone, walk towards it. If not, do nothing.
|
public void walkTowardsPheromone()
    {
        Actor ph = getOneIntersectingObject(Pheromone.class);
        if (ph != null) {
            headTowards(ph);
            walk();
            if (ph.getX() == getX() && ph.getY() == getY()) {
                foundLastPheromone = PH_TIME;
            }
        }
    }
}