as3 - Detect if object is moved to another object using timer - actionscript-3

Question

I was creating a shooting game that the target is appear and disappear any seconds. I don't know how use the codes and I don't know how to detect the object to object when using if statement.
Here's my codes:
import flash.utils.Timer;
var dummySX: Number = dummyS.x;
var dummySY: Number = dummyS.y;
var targetTimeStart: Timer = new Timer(1000);
targetTimeStart.start();
targetTimeStart.addEventListener(TimerEvent.TIMER, targetTimeStartNow);
function targetTimeStartNow(e: TimerEvent): void {
target.x = dummySX;
target.y = dummySY;
targetTimeStart.stop();
}
function detect(): void {
if ((target.x == dummySX) && (target.y == dummySY)) {
trace("DETECTED");
}
}
or
function detect(): void {
if (target.hitTestObject(dummyS)==true) {
trace("DETECTED");
}
}
Thanks!!

Answer 1

There are several ways to detect hit between objects.
Let's say you have 2 display objects (do1 and do2)
First of all there is the do1.hitTestObject(do2). This method is very fast and works well for rectangular objects. You can get some visually "false" results if the rectangular objects are rotated or you use it with other than rectangular objects.
Next there is the do1.hitTestPoint(do2.x, do2.y, shapeFlag). This method is slower but more accurate, especially when you set the shapeFlag to true. It tests the hit against a single point (x & y coordinates).
There is a third method (hitTest) that implies you use BitmapData objects and that is even more precise and is specific the the BitmapData class, but much harder to process (being able to ignore transparent pixels).
A fourth option would be to do a custom implementation of the hit detection, but it seems a bit off to detail that here.
Going over your code, I see you create a 1 second Timer object and start it, after which you add a listener with the targetTimeStartNow function. In that function you move the target object to the same position of the dummyS object and after that you stop the targetTimeStart Timer object. That means that you have only 1 entry in that function.
The detect function seems that is never called from your code, although both calls should trace DETECTED.
The first detect function that you've written mimics the hitTestPoint version.
function detect(): void {
if ((target.x == dummySX) && (target.y == dummySY)) {
trace("DETECTED");
}
}
This is the same with:
function detect():void {
if(target.hitTestPoint(dummySX, dummySY, false)) {
trace("DETECTED");
}
}
It'd be better to use this variant (in order to use the shape of the object, and not their bounding box):
function detect():void {
if(target.hitTestPoint(dummySX, dummySY, true)) {
trace("DETECTED");
}
}
The second detect function uses the hitTestObject and it's ok. You could use it without explicitly == true:
function detect(): void {
if(target.hitTestObject(dummyS)) {
trace("DETECTED");
}
}
The only thing is to call it in code in order to get it executed. So somewhere after the target object was moved just add:
detect();
Depending on your needs, you could add it to the targetTimeStartNow method (or add an EnterFrame listener, or create another Timer object):
function targetTimeStartNow(e: TimerEvent): void {
target.x = dummySX;
target.y = dummySY;
targetTimeStart.stop();
detect();
}