Greenfoot

JasonZhu

2013/9/27

#

    public void addAthids(int a)
    {
        for(int athid=0; athid<a; athid++) {
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());
            addObject( new Athid(), x, y);
        }
        athidSpawn++;
        if (athidSpawn==50){           
            int x = Greenfoot.getRandomNumber(getWidth());
            int y = Greenfoot.getRandomNumber(getHeight());            
            addObject( new Athid(), x, y);
            athidSpawn=0;        
        }            
    }

Because it only creates the initial amount, but none spawns. Thanks for any help I get in advance!

JasonZhu

2013/9/27

#

I have a feeling it has something to do with the "int a", however, woulding that only limit the value of "a" athids allowed in the World even with the spawn?

Zamoht

2013/9/27

#

What is it that you want? I know this may seem like an odd question, but I'm not sure what your goal is exactly.

JasonZhu

2013/9/27

#

How do I spawn objects when the program is running while when compiling the program, have an initial amount the object in the world?

Zamoht

2013/9/27

#

Oh I see. Your code above can be used for adding the initial amount.

public void addAthids(int a)  
{  
    for(int athid=0; athid<a; athid++) {  
        int x = Greenfoot.getRandomNumber(getWidth());  
        int y = Greenfoot.getRandomNumber(getHeight());  
        addObject( new Athid(), x, y);  
    }         
}

Use this method in the world constructor. I will show you two ways of spawning objects while the program is running. First the constant time based. For this you will need a counter in your world:

private int spawnCounter;

Then add the act method to your world:

public void act()
{
    if (spawnCounter++ > 200) //Use whatever constant you want instead of 200
    {
        addObject(new Athid(), Greenfoot.getRandomNumber(getWidth()), Greenfoot.getRandomNumber(getHeight()));
        spawnCounter = 0;
    }
}

The other thing you can do is the random time based spawning. For this you do not need any counter variable.

public void act()
{
    if (Greenfoot.getRandomNumber(100) < 30) //This will give a 30% chance to spawn an object every act
    {
        addObject(new Athid(), Greenfoot.getRandomNumber(getWidth()), Greenfoot.getRandomNumber(getHeight()));
    }
}

danpost

2013/9/28

#

To retain a specific number of athids in the world, use this for your addAthids method and call it from your act method:

public void addAthids(int a)
{
    if (getObjects(Athid.class).size() < a)
    {
        int x = Greenfoot.getRandomNumber(getWidth());
        int y = Greenfoot.getRandomNumber(getHeight());
        addObject(new Athid(), x, y);
    }
}

You could use 'while' instead of 'if' if you like; but there will be little difference in performance. And you do not have to initially spawn any in the constructor.

JasonZhu

2013/9/28

#

I understand now, thanks guys and sorry for the late post.

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Is this how I spawn objects while having an initial amount in the World?