Greenfoot Explosion

World

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

/**
* Write a description of class Space here.
*
* @author (your name)
* @version (a version number or a date)
*/

import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.awt.Color;
/**
* Write a description of class MyWorld here.
*
* @author (your name)
* @version (a version number or a date)
*/


public class Space extends World
{

/**
* Constructor for objects of class Space.
*
*/
public Space()
{
// Create a new world with 20x20 cells with a cell size of 10x10 pixels.
super(400, 400, 1);
GreenfootImage bg = getBackground();
bg.setColor(Color.BLACK);
bg.fill();
createStars(200);
}

private void createStars(int numberOfStars)
{
GreenfootImage bg = getBackground();
bg.setColor(Color.GRAY);
for (int i = 0; i < numberOfStars; i++) {
int x = Greenfoot.getRandomNumber(getWidth() );
int y = Greenfoot.getRandomNumber(getHeight() );
bg.fillOval(x,y,2,2);
}
}
}

Explosion

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

import java.util.*;

/**
* An explosion. It starts by expanding and then collapsing.
* The explosion will explode other obejcts that the explosion intersects.
*
* @author Poul Henriksen
* @version 1.0.1
*/
public class Explosion extends Actor
{
/** How many images should be used in the animation of the explostion */
private final static int IMAGE_COUNT= 8;

/**
* The images in the explosion. This is static so the images are not
* recreated for every object (improves performance significantly).
*/
private static GreenfootImage[] images;

/** Current size of the explosion */
private int size=0;

/** How much do we increment the index in the explosion animation. */
private int increment=1;

public Explosion() {

initialiseImages();
setImage(images[0]);
Greenfoot.playSound("Explosion.wav");
}

/**
* Create the images for explosion.
*/
public synchronized static void initialiseImages() {
if(images == null) {
GreenfootImage baseImage = new GreenfootImage("explosion.png");
int maxSize = baseImage.getWidth()*4;
int delta = maxSize / (IMAGE_COUNT+1);
int size = 0;
images = new GreenfootImage[IMAGE_COUNT];
for(int i=0; i < IMAGE_COUNT; i++) {
size = size + delta;
images[i] = new GreenfootImage(baseImage);
images[i].scale(size, size);
}
}
}

/**
* EXPLODE!
*/
public void act()
{
setImage(images[size]);

size += increment;
if(size>=IMAGE_COUNT) {
increment = -increment;
size += increment;
}

explodeOthers();
if(size <= 0) {
getWorld().removeObject(this);
}
}

/**
* Explodes all intersecting objects.
*/
private void explodeOthers()
{
List explodeEm = getIntersectingObjects(null);
Iterator i = explodeEm.iterator();
while(i.hasNext()) {
Actor a = (Actor) i.next();
if( ! (a instanceof Explosion)) { //Don't explode other explosions
int x = a.getX();
int y = a.getY();
//Replace other object with an explosion
getWorld().removeObject(a);
getWorld().addObject(new Explosion(), x, y);
}
}
}
}