Greenfoot

Har8mes

2021/1/29

#

Hi, I'm currently writing a program where a Lobster is chasing a Crab and I'm stuck currently getting the Crab rotate a random amount away from the Lobster. Here is the Part I've got some problems... PS: Note that i'm not finished with the I've put in.

 public void isatEdge()
    {
       if (isAtEdge()) {
           if (!getWorld().getObjects(Lobster.class).isEmpty())
           {
              Actor player = (Lobster)player.getX(0);
              int playerX = player.getX();
              int playerY = player.getY(); 
           } 
       } else {
           move(-50);
           turn(45 - Greenfoot.getRandomNumber(90));
       }
    }

RcCookie

2021/1/29

#

Well if you want to turn away from an actor you can use

Actor other = someWayToGetTheActor();
turnTowards(other.getX(), other.getY());
turn(180);

So if you want to turn away with 90 degrees of randomness, you can replace the last line with this:

turn(135 + Greenfoot.getRandomNumber(90));

Har8mes

2021/1/29

#

Thnx for the reply, It could sound stupid but what do i put in "someWayToGetTheActor();" because i get an error??

Roshan123

2021/1/29

#

Har8mes wrote...

Thnx for the reply, It could sound stupid but what do i put in "someWayToGetTheActor();" because i get an error??

(xyz)getOneInsertingObject(xyz.class);

Har8mes

2021/1/29

#

So I put in the code but it doesn't work:

 public void dodgeLobster()
    {
        if (!getWorld().getObjects(Lobster.class).isEmpty())
           {
              Actor other = getOneIntersectingObject(Lobster.class);
              turnTowards(other.getX(), other.getY());
              turn(180);
        }
    }
}

Har8mes

2021/1/29

#

That is fixed but i have still a problem at line 6. When i start my program it says: java.lang.NullPointerException at Crab.dodgeLobster(Crab.java:53) at Crab.act(Crab.java:15)

Roshan123

2021/1/29

#

Actor other = (Lobster)getOneIntersectingObject(Lobster.class);

Roshan123

2021/1/29

#

This may work

public void dodgeLobster()
    {
Actor other = getOneIntersectingObject(Lobster.class);
        if (!getWorld().getObjects(Lobster.class).isEmpty() && other!=null)
           {
              
              turnTowards(other.getX(), other.getY());
              turn(180);
        }
    }
}

Har8mes

2021/1/29

#

Either i missed something or the code still doesn't work. I get an error code that something is wrong with "turnTowards(other.getX(), other.getY());"

 public void dodgeLobster()
    {
        if (!getWorld().getObjects(Lobster.class).isEmpty())
           {
              Actor other = (Lobster)getOneIntersectingObject(Lobster.class);
              turnTowards(other.getX(), other.getY());
              turn(180);
        }
    }
}

Roshan123

2021/1/29

#

Roshan123 wrote...

This may work

public void dodgeLobster()
    {
Actor other = (Lobster)getOneIntersectingObject(Lobster.class);
        if (!getWorld().getObjects(Lobster.class).isEmpty() && other!=null)
           {
              
              turnTowards(other.getX(), other.getY());
              turn(180);
        }
    }
}

Paste it and not the above one I forgot to change line 3

danpost

2021/1/29

#

public void dodgeLobster()
{
    Actor lobster = getOneIntersectingObject(Lobster.class);
    if (lobster != null)
    {
        turnTowards(lobster.getX(), lobster.getY());
        turn(135+Greenfoot.getRandomNumber(91));
    }
}

Har8mes

2021/1/29

#

ok nvm what i replied I tested it 3 times but why does it teleport so weird??

public class Crab extends Actor. I've put my whole code in this messge so you can comprehend my code:
{   int AmountEatenPizza = 0;
    int PizzaLeft = 7;
    public void act()
    {
       move(10);  
       eatPizza();
       isatEdge();
       VictoryCondition();
       dodgeLobster();
    }  
    public void eatPizza() 
    {
      if(isTouching(pizza.class)) {
         removeTouching(pizza.class);
         Greenfoot.playSound("slurp.wav");
         AmountEatenPizza = AmountEatenPizza + 1;                
         PizzaLeft = PizzaLeft - 1;
         int x = Greenfoot.getRandomNumber(500);
         int y = Greenfoot.getRandomNumber(1000);
         getWorld().addObject(new pizza(), x,y);
         System.out.println("You've eaten "+ AmountEatenPizza + " much pizza!!"); 
         System.out.println("There is " + PizzaLeft + " Pizza left to eat!!"); 
      }
    }
    public void isatEdge()
    {
       if (isAtEdge()) {
           move(-10);
           turn(Greenfoot.getRandomNumber(90) + 135);
           } else {
           move(10);
           turn(Greenfoot.getRandomNumber(90) + 135); 
       }
    }
    public void  VictoryCondition() 
    {
        if (AmountEatenPizza == 7) {
            System.out.println("You've won!!!");
            Greenfoot.stop();
        }
    }
    public void dodgeLobster()
    {
          Actor lobster = getOneIntersectingObject(Lobster.class);
          if (lobster != null)
          {
              turnTowards(lobster.getX(), lobster.getY());
              turn(135+Greenfoot.getRandomNumber(91));
          }   
    }
}

danpost

2021/1/29

#

Insert before turnTowards:

move(-10);

to get off lobster. Remove lines 31 thru 33.

Har8mes

2021/1/29

#

Now It's working as it was planned!!! Thank you guys for your help!!!!

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How to rotate an actor away from another actor??