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coder04
coder04 wrote ...

2014/9/18

How do you make enemies shoot

coder04 coder04

2014/9/18

#
This is my enemy class which needs to shoot 
import greenfoot.*; 

public class Miniship extends Actor
{
    public void act()
    {
        move(4);
        randomTurn();
        turnAtEdge();
    }
    
    /**
     * With a 10% probability, turn a bit right or left.
     */
    public void randomTurn()
    {
        if ( Greenfoot.getRandomNumber(100) < 10 )
        {
            turn( Greenfoot.getRandomNumber(40)-20 );
        }        
    }
    
    /**
     * If we reach the edge of the world, turn a little bit.
     */
    public void turnAtEdge()
    {
        if (atWorldEdge())
        {
            turn(7);
        }
    }
    public boolean atWorldEdge()  
    {  
        if(getX() < 10 || getX() > getWorld().getWidth() - 10)  
            return true;  
        if(getY() < 10 || getY() > getWorld().getHeight() - 10)  
            return true;  
        else  
            return false;  
    }    
}
Super_Hippo Super_Hippo

2014/9/18

#
You will need a class which represents the bullet. You write a new method which adds a bullet object at the position of this Miniship with the same rotation (or with a fixed turn, depends on the images or if you want them to target you for example). Of course you should not add a bullet every act cycle, so you create a timer and let the Miniship only shoot when the timer reached a given value.
coder04 coder04

2014/9/18

#
i have got a shot class but i have got no code in it. i know how to make it kill me but i need to know how to spawn the bullet and shoot straight or target me.
Super_Hippo Super_Hippo

2014/9/18

#
Don't you also shoot with your ship? Then you should already know how to spawn the bullet. To set the rotation, you can give the 'Shot' class a parameter in the constructor and pass the rotation of the ship there. If you want it to target you, you can use the 'turnTowards' method. As an alternative, which I used in my Space Shooter scenario for the enemies which shoot at you, I calculated the rotation "by hand". 
            double x = Welt.schiff.getExactX()-getExactX();
            double y = Welt.schiff.getExactY()-getExactY();
            double s = Math.atan2(y,x);
            s = Math.toDegrees(s);
('Welt' is the World class and 'schiff' is the public field which holds the ship object.) Then you can do something like 
getWorld().addObject(new Shot( (int) s), getX(), getY() );
Or easier, just use 'turnTowards' instead. I am not 100% sure, but I guess this method isn't possible in the constructor, because it needs the position in the world. So you can use the 'addedToWorld' method to call this 'turnTowards' there.
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