import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class rock here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class rock extends AnimBase
{
    /**
     * Act - do whatever the rock wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    int speed = 2;
    public void act() 
    {
        move();
        checkCollision();
        checkCollisionBoundary();
    }    
    public void move(){
        int y = getY();
        setLocation(getX(),y+speed);
    }
    private void checkForBorder()
    {
        World world = getWorld();
        int y = world.getHeight();
        if(getY()==y){
            getWorld().removeObject(this);
        }
    }
    private void checkCollisionBoundary(){
        int y = getY();
        int maxy = getWorld().getHeight()-1;
        if(getWorld(this)==null){
            if(y==maxy){
            getWorld().removeObject(this);
        }
    }
    }
    private void checkCollision(){
        World world;
        world=getWorld();
        Object obj=world.getObjects(Ship.class).get(0);
        Ship ship=(Ship) obj;
        int shipX=ship.getX();
        int shipY=ship.getY();
        Actor topLeftShip = getOneObjectAtOffset(shipX/-2,shipY/2,Ship.class);
        Actor topRightShip = getOneObjectAtOffset(shipX/2,shipY/2,Ship.class);
        if(topLeftShip != null || topRightShip != null){
            world.removeObject(this);
        }
    }
}