AS3 Pass Object - actionscript-3

Question

I have 3 Classes.
One is a Global class that has my function:
public static function getDistance(ObjOne, ObjTwo)
{
var distance = Math.sqrt( ( ObjOne.x - ObjTwo.x ) * ( ObjOne.x - ObjTwo.x ) + ( ObjOne.y - ObjTwo.y ) * ( ObjOne.y - ObjTwo.y ) );
return distance;
}
Then I have a MovieClip that is the class: Minion and another called: Turret
In the Minion class I am calling: Global.getDistance
And setting the args to: Global.getDistance(this, ?????)
How can I get the Turret Object from the Turret class for the final param?

Answer 1

If each minion has a single turret that it is targeting, then you should hold a reference to the turret inside of your Minion class. There should be no need for a static function to get distance (unless it's used for other things besides the minion/turret relation).
For your turrets to be aware of ALL minions (to decide which minion to attack), a good way to do this is to store them all in a statically assessable vector (array).
Here would be a sample of your Minion class:
public class Minion {
public static var allMinions:Vector<Minion> = new Vector<Minion>(); //create a static array to store all your minions
public var turret:Turret;
public function Minion(targetTurret:Turret):void {
turret = targetTurret;
this.addEventListener(Event.ADDED_TO_STAGE,addedToStage,false,0,true);
this.removeEventListener(Event.REMOVED_FROM_STAGE,removedFromStage,false,0,true);
}
private function addedToStage(e:Event):void {
allMinions.push(this); //add this minion instance to the array when it's added to the display list
}
private function removedFromStage(e:Event):void {
//remove this minion instance from the array of all minions when it's removed from the display list
var index:int = allMinions.indexOf(this);
if(index >= 0){
allMinions.splice(index,1);
}
}
private function move():void { //whatever function you use to move the minion along
//get distance here, using your local turret var
getDistance(this,turret); //this could be a local function, or some static function somewhere - local is faster, especially if being called everyframe or in a loop.
}
//a function to take damage, returns true if still alive after the damage
public function takeDamage(amount:Number):Boolean {
this.health -= amount * armor; //armor could be a value between 1 (no armor) and 0 (invincible)
if(health <= 0){
//die
return false;
}
return true;
}
}
This passes in the appropriate turret when you create a new Minion - new Minion(turretInstance), and has a statically accessible array that holds all the minions that are on the display list at any given time. It also adds a function to take damage
For the turrets to attack, you'd want to scan the array of all minions, and determine which are close enough to attack, either attack all (if that's the type of turret) or pick one (the closest one usually) to attack.
Turret class:
public var range:Number = 200; //how close to the turret a minion needs to be before it can attack
public var attackPower:Number = 10; //how much damage does this turret cause
public function attack():void {
//this for loop goes through all the minions and finds the closest one
var closestMinion:Minion;
var tmpDistance:Number; //
var distance:Number;
for each(var minion:Minion in Minion.allMinions){
distance = Math.sqrt( ( minion.x - this.x ) * ( minion.x - this.x ) + ( minion.y - this.y ) * ( minion.y - this.y ) ); //find the distance between the current minion in the loop and this turret
if(distance < range && isNaN(tmpDistance) || distance < tmpDistance){ //if the distance of this minion is less than the current closest, make the current closest this one
closestMinion = minion;
tmpDistance = distance;
}
}
//attack the closest one
if(closestMinion){
closestMinion.takeDamage(attackPower);
}
}

Answer 2

If there is only one Turret in your game, you could use the singleton design pattern.
private static var instance:Turret = null;
public static function getInstance()
{
if(instance === NULL)
instance = new Turret();
return instance;
}
So you can call Turret.getInstance() and use your Turret object. Hope it helps. If you have more than one turret you should have a game class with an array or vector with all your turrets.

Answer 3

I have no idea what you exactly need, the type of the second parameter? Since your dealing with a global function, i would suggest to just use DisplayObject since both have x/y properties
public static function getDistance(clip1:DisplayObject, clip2:DisplayObject):Number
{
return Math.sqrt( ( clip1.x - clip2.x ) * ( clip1.x - clip2.x ) + ( clip1.y - clip2.y ) * ( clip1.y - clip2.y ) );
}