Tutorial: Create a Tower Defense Game in AS2 – Part 6
Categories: Flash
Table of Contents
Step 6: Expanding on the Game
Welcome to the 6th part of the tutorial, Expanding on the Game! Well, what do I mean by “Expanding”? Well, by expanding, I mean that we’re going to create more enemies and more levels. Sounds pretty cool, doesn’t it?
Open up “source.fla” and find the makeEnemies function. We’re going to have some major renovations to this functions. Just replace the function with this new code:
function makeEnemies():Void{//this function will add enemies to the field
if(enemyTime < enemyLimit){//if it isn't time to make them yet
enemyTime ++;//then keep on waiting
} else {//otherwise
var theCode:Number = enemyArray[currentLvl-1][currentEnemy];//get the code from the array
if(theCode != 0 && theCode != null){//if it's not set at 0
//then create a new enemy and add it to the enemy holder
enemyHolder.createEmptyMovieClip('enemy'+currentEnemy,enemyHolder.getNextHighestDepth());
//now we're going to draw the enemy. It'll just be a tiny red circle
enemyHolder['enemy'+currentEnemy].beginFill(0xFF0000);//coloring them red gray
enemyHolder['enemy'+currentEnemy].moveTo(0, 2.5);//move the entire shape a certain way
//create 4 curves so that it'll look like a circle
enemyHolder['enemy'+currentEnemy].curveTo(0,10,5,10);
enemyHolder['enemy'+currentEnemy].curveTo(10,10,10,5);
enemyHolder['enemy'+currentEnemy].curveTo(10,0,5,0);
enemyHolder['enemy'+currentEnemy].curveTo(0,0,0,5);
enemyHolder['enemy'+currentEnemy].endFill();//end the fill
//add a few variables to the enemy
enemyHolder['enemy'+currentEnemy].enLevel = theCode;//setting its level to be what # it is
enemyHolder['enemy'+currentEnemy].maxSpeed = 3;//how fast it can possibly go
enemyHolder['enemy'+currentEnemy].xSpeed = 0;
enemyHolder['enemy'+currentEnemy].ySpeed = 0;
enemyHolder['enemy'+currentEnemy].health = 5*theCode;
//checking what the start direction is
if(_root.startDir == 'UP'){//if it's starting up
enemyHolder['enemy'+currentEnemy]._y = 300;//set the y value off the field
enemyHolder['enemy'+currentEnemy]._x = _root.startCoord;//make the x value where it should be
enemyHolder['enemy'+currentEnemy].xSpeed = 0;//make it not move horizontally
enemyHolder['enemy'+currentEnemy].ySpeed = -enemyHolder['enemy'+currentEnemy].maxSpeed;//make it move upwards
} else if(_root.startDir == 'RIGHT'){//and so on for other directions
enemyHolder['enemy'+currentEnemy]._x = -25;
enemyHolder['enemy'+currentEnemy]._y = _root.startCoord;
enemyHolder['enemy'+currentEnemy].xSpeed = enemyHolder['enemy'+currentEnemy].maxSpeed;
enemyHolder['enemy'+currentEnemy].ySpeed = 0;
} else if(_root.startDir == 'DOWN'){
enemyHolder['enemy'+currentEnemy]._y = -25;
enemyHolder['enemy'+currentEnemy]._x = _root.startCoord;
enemyHolder['enemy'+currentEnemy].xSpeed = 0;
enemyHolder['enemy'+currentEnemy].ySpeed = enemyHolder['enemy'+currentEnemy].maxSpeed;
} else if(_root.startDir == 'LEFT'){
enemyHolder['enemy'+currentEnemy]._x = 550;
enemyHolder['enemy'+currentEnemy]._y = _root.startCoord;
enemyHolder['enemy'+currentEnemy].xSpeed = -enemyHolder['enemy'+currentEnemy].maxSpeed;
enemyHolder['enemy'+currentEnemy].ySpeed = 0;
}
enemyHolder['enemy'+currentEnemy]._x += 5;//fixing the x value
enemyHolder['enemy'+currentEnemy]._y += 5;//fixing up the y value
enemyHolder['enemy'+currentEnemy].onEnterFrame = function(){//give it some functions
this._x += this.xSpeed;
this._y += this.ySpeed;
//checking what direction it goes when finishing the path
if(_root.finDir == 'UP'){//if it finishes at the top
if(this._y <= -25){//if the y value is too high
_root.lives --;//take away a life
_root.money -= 5*this.enLevel;//don't let the player gain any money
this.removeMovieClip();//take it away from the stage
}
} else if(_root.finDir == 'RIGHT'){//and so on for other directions
if(this._x >= 550){
_root.lives --;
_root.money -= 5*this.enLevel;
this.removeMovieClip();
}
} else if(_root.finDir == 'DOWN'){
if(this._y >= 300){
_root.lives --;
_root.money -= 5*this.enLevel;
this.removeMovieClip();
}
} else if(_root.startDir == 'LEFT'){
if(this._x <= 0){
_root.lives --;
_root.money -= 5*this.enLevel;
this.removeMovieClip();
}
}
if(this.health <= 0){
_root.enemiesLeft --;
_root.money += 5*this.enLevel;
this.removeMovieClip();
}
}
}
currentEnemy ++;//move on to the next enemy
enemyTime = 0;//and reset the time
}
}
There aren't very many renovations that we've made, but they will make our code much more flexible. It allows us to create different enemy levels by setting the enLevel to be equal to the code that is placed into the enemy array. The enLevel in turn lets us dynamically change the amount of health the enemy has and the amount of money that it gives you when you kill it. Right now the health and money it gives you is 5 times the enemy level.
Now, we can make more levels with better enemies! You can customize your own levels, or use the ones I created by setting these values in the enemyArray:
enemyArray = [//defining the array
[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],//1's will just represent an enemy to be created
[2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2],//another row means another level
[3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3],
[100],
[5,6,7,6,5,6,7,6,5,6,7,6,5,6,7,6,5,6,7,6,5,6,7,6,5,6,7,6,5],
[250,250,250]
];
Of course, I'd suggest creating your own levels, as mine aren't what you would call the best. Anyways, this wraps up the second to last part of this tutorial. Join us next time when finish up this little game!