Flash prototype of a game like Balloon Invasion

March 1, 2008 • Flash, Game design by Emanuele Feronato • 10 Comments

One of the latest successful games released last week was Balloon Invasion.

It’s a mix between an artillery and a defense game, with a World War II theme.

I made a little prototype of the game, that will be explained another day. It’s nothing so interesting, just a mix between Create a flash artillery game and Managing multiple collision detection with Flash tutorials.

That’s the good point when you write a lot of code: the more you write, the more you can recycle.

The main difference however is the firing system: enemies don’t get hurt by bullets but mby explosions bullets make when they come to the spot you fired on… just like “real” artillery

Mouse.hide();
attachMovie("crosshair","crosshair",1);
attachMovie("tank","tank",2,{_x:450, _y:350});
fire_array = new Array();
fire_delay = 30;
just_fired = 0;
crosshair.onEnterFrame = function() {
	this._x = _xmouse;
	this._y = _ymouse;
};
tank.onEnterFrame = function() {
	mousex = _xmouse-this._x;
	mousey = (_ymouse-this._y)*-1;
	angle = Math.atan(mousey/mousex)/(Math.PI/180);
	if (mousex<0) {
		angle += 180;
	}
	if (mousex>=0 && mousey<0) {
		angle += 360;
	}
	if (angle>160) {
		angle = 160;
	}
	if (angle<20) {
		angle = 20;
	}
	firepower = Math.sqrt(mousex*mousex+mousey*mousey);
	if (firepower>200) {
		firepower = 200;
	}
	this.cannon._rotation = angle*-1;
};
function onMouseDown() {
	if (just_fired>fire_delay) {
		just_fired = 0;
		angle = tank.cannon._rotation;
		start_ball_x = tank._x+48*Math.cos(angle*Math.PI/180);
		start_ball_y = tank._y+48*Math.sin(angle*Math.PI/180);
		cannonball_fired = attachMovie("cannonball", "cannonball_"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:start_ball_x, _y:start_ball_y});
		cannonball_fired.dirx = Math.cos(angle*Math.PI/180)*firepower;
		cannonball_fired.diry = Math.sin(angle*Math.PI/180)*firepower;
		cannonball_fired.fire_coord_x = _root._xmouse;
		cannonball_fired.fire_coord_y = _root._ymouse;
		cannonball_fired.onEnterFrame = function() {
			this._x += this.dirx/50;
			this._y += this.diry/50;
			dist_x = this._x-this.fire_coord_x;
			dist_y = this._y-this.fire_coord_y;
			dist = Math.sqrt(dist_x*dist_x+dist_y*dist_y);
			if (dist<20) {
				fire_array.push("explosion"+_root.getNextHighestDepth());
				exp = attachMovie("explosion", "explosion"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:this._x, _y:this._y});
				exp.onEnterFrame = function() {
					this._width += 2;
					this._height += 2;
					this._alpha -= 2;
					if (this._alpha<0) {
						for (x in fire_array) {
							if (this.name == _root[fire_array[x]].name) {
								fire_array.splice(x,1);
							}
						}
						this.removeMovieClip();
					}
				};
				this.removeMovieClip();
			}
		};
	}
}
_root.onEnterFrame = function() {
	just_fired++;
	new_enemy = Math.random()*100;
	if (new_enemy<1) {
		enemy = attachMovie("enemy", "enemy"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:-40, _y:Math.random()*200+50});
		enemy.speed = Math.random()*2+1;
		enemy.onEnterFrame = function() {
			this._x += this.speed;
			if (this._x>550) {
				this.removeMovieClip();
			}
			for (x in fire_array) {
				dist_x = this._x-_root[fire_array[x]]._x;
				dist_y = this._y-_root[fire_array[x]]._y;
				dist = Math.sqrt(dist_x*dist_x+dist_y*dist_y);
				if (dist<(this._width+_root[fire_array[x]]._width)/2) {
					this._alpha -= 5;
					if (this._alpha<0) {
						this.removeMovieClip();
					}
				}
			}

		};
	}
};

Mouse.hide();

attachMovie("crosshair","crosshair",1);

attachMovie("tank","tank",2,{_x:450, _y:350});

fire_array = new Array();

fire_delay = 30;

just_fired = 0;

crosshair.onEnterFrame = function() {

this._x = _xmouse;

this._y = _ymouse;

};

tank.onEnterFrame = function() {

mousex = _xmouse-this._x;

mousey = (_ymouse-this._y)*-1;

angle = Math.atan(mousey/mousex)/(Math.PI/180);

if (mousex<0) {

angle += 180;

}

if (mousex>=0 && mousey<0) {

angle += 360;

}

if (angle>160) {

angle = 160;

}

if (angle<20) {

angle = 20;

}

firepower = Math.sqrt(mousex*mousex+mousey*mousey);

if (firepower>200) {

firepower = 200;

}

this.cannon._rotation = angle*-1;

};

function onMouseDown() {

if (just_fired>fire_delay) {

just_fired = 0;

angle = tank.cannon._rotation;

start_ball_x = tank._x+48*Math.cos(angle*Math.PI/180);

start_ball_y = tank._y+48*Math.sin(angle*Math.PI/180);

cannonball_fired = attachMovie("cannonball", "cannonball_"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:start_ball_x, _y:start_ball_y});

cannonball_fired.dirx = Math.cos(angle*Math.PI/180)*firepower;

cannonball_fired.diry = Math.sin(angle*Math.PI/180)*firepower;

cannonball_fired.fire_coord_x = _root._xmouse;

cannonball_fired.fire_coord_y = _root._ymouse;

cannonball_fired.onEnterFrame = function() {

this._x += this.dirx/50;

this._y += this.diry/50;

dist_x = this._x-this.fire_coord_x;

dist_y = this._y-this.fire_coord_y;

dist = Math.sqrt(dist_x*dist_x+dist_y*dist_y);

if (dist<20) {

fire_array.push("explosion"+_root.getNextHighestDepth());

exp = attachMovie("explosion", "explosion"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:this._x, _y:this._y});

exp.onEnterFrame = function() {

this._width += 2;

this._height += 2;

this._alpha -= 2;

if (this._alpha<0) {

for (x in fire_array) {

if (this.name == _root[fire_array[x]].name) {

fire_array.splice(x,1);

}

this.removeMovieClip();

}

};

this.removeMovieClip();

}

};

}

_root.onEnterFrame = function() {

just_fired++;

new_enemy = Math.random()*100;

if (new_enemy<1) {

enemy = attachMovie("enemy", "enemy"+_root.getNextHighestDepth(), _root.getNextHighestDepth(), {_x:-40, _y:Math.random()*200+50});

enemy.speed = Math.random()*2+1;

enemy.onEnterFrame = function() {

this._x += this.speed;

if (this._x>550) {

this.removeMovieClip();

}

for (x in fire_array) {

dist_x = this._x-_root[fire_array[x]]._x;

dist_y = this._y-_root[fire_array[x]]._y;

dist = Math.sqrt(dist_x*dist_x+dist_y*dist_y);

if (dist<(this._width+_root[fire_array[x]]._width)/2) {

this._alpha -= 5;

if (this._alpha<0) {

this.removeMovieClip();

}

};

}

};

And here’s the result:

Download the source code and start cloning the game :)

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This post has 10 comments

EagleVision

on March 1, 2008 at 11:38 pm

WOW! I like this….Real nice…I am so going to do it when I get back home! :D
Jack Hopkisn

on March 1, 2008 at 11:55 pm

I like it!
It reminds me of ‘Mutually assured destruction’
vincent

on March 2, 2008 at 8:24 pm

wow thanks man this is verry usefull for me :)
Andy

on March 3, 2008 at 4:45 am

How do you actually feel about Kongregate?
Thomas

on March 3, 2008 at 8:53 am

Awesome =D!
xavi-v

on March 3, 2008 at 7:02 pm

hey, i was trying to think of a way to do the feature of the ball exploding where the mouse is pressed. I couldn’t do it because i am not as good as Emanuele. Thanks for being phsycic emanuele! =)
xavi-v

on March 3, 2008 at 7:04 pm

i wanted to make a space defence game where the turret was in the middle of the screen. Hey! I just had a great idea. NUCLEAR WAR! the ICBM’s will go to where the mouse clicks! thanks emanuele!!!!!!!!!!!!!!!!!!!!
Displaying enemiy’s energy bar in Flash games : Emanuele Feronato - italian geek and PROgrammer

on March 6, 2008 at 1:52 pm

[...] time to show you how can you do this. In this example, I will start from the Flash prototype of a game like Balloon Invasion example but obviously you can apply the same concept to whatever game you [...]
Pyper

on April 23, 2008 at 6:26 pm

I think I love you! lol!
Thank you soo much, great tutorials.
Madge

on August 18, 2011 at 11:00 am

Woot, I will cetairlny put this to good use!

italian geek and PROgrammer

This post has 10 comments

Jack Hopkisn

vincent

Andy

Pyper