[F9]Tips from starting with AS3

If people are looking to get up and running with AS3 but don't have the editor, you can use FlashDevelop from www.flashdevelop.org and follow the directions on that site to use the flex2 sdk to handle compiling. If you are doing things 100% in code, it works great.

Whats the problem with f9 public alpha?

Once you're used to a dev system like FDT it's really impossible to go back to the standard IDE. Simple as that really.

Squize.

Change it inside a TextFormat object and give it to the TextField object
I mean,once you have your TextFiel

Code:

---

vat te:TextField = new TextField();

---

create your TextFormat

Code:

---

var fo:TextFormat = new TextFormat();
fo.font = "Arial";
fo.size = 15;

---

and put it in the defaultTextFormat property of your TextField

Code:

---

te.defaultTextFormat = fo;

te.text = "blablabla";
addChild(te);

---

You can change other things like color, bold, italic
italic and bold are just boolean stuff, give it a true if you want to use it

Code:

---

fo.bold = true;
fo.italic = true;
fo.color = 0xFF0000;

---

There are other things you can do with TextFormat, like create links, but they are not much game related, i think

This is an old fps counter that someone here mades in AS1/2 whatever, and i have tried to convert it in AS3, i bet it can be improved, since i dont understand completely how it works
Anyway, using it may save you some minutes in your life
usage:

var fp:fpsCounter = new fpsCounter(this);
addChild(fp);

Obs:this (this) is for it to have a reference to what was called "_root"
There are better ways for it to have it,i just dont use cos f9 public alpha dont have it

Code:

---


package{
        import flash.display.Sprite;
        import flash.text.TextField;
        import flash.events.Event;
        class fpsCounter extends Sprite{
                var rr:Object;
                var FPS:TextField;
                var my_date:Date;
                var startTime: Number;
                var currTime:Number;
                var elapsedTime:Number;
                var count:Number;
               
                function fpsCounter(rut){
                        rr = rut;
                        rr.addEventListener("enterFrame", this.oef);
                        FPS = new TextField();
                        addChild(FPS);
                       
                        my_date = new Date();
                        startTime = my_date.time;
                        currTime = 0;
                        elapsedTime = 0;
                       
                        count = 0;
                       
                }
                function oef(ev:Event){
                        my_date = new Date();
                        currTime = my_date.time;
                       
                        elapsedTime = currTime - startTime;
                       
                        count ++;
                       
                        if (elapsedTime>1000) {
                    FPS.text = count.toString();
                    count = 0;
                }
                if (elapsedTime>1000) {
                    my_date = new Date();
                    startTime = my_date.time;
                }
                if (FPS == NaN) {
                    FPS = 0;
                }
                       
                       
                }
        }
}

---

Cool thread! Here's a nice little new thing in AS3 - labels.

code:

---

myLabel: for ( int j = 0; j < 30; j ++ )

{

  for ( int i = 0; i < 30; i ++ )

  {

     if ( condition ) break myLabel;

  }

}

---

It's not really that useful, but I think it's elegant. Works on
any code block.

I'm surprised "for each.." isn't covered yet. Really useful.

code:

---

var asd:Array = [ "one", "two", "three" ];

for ( var i in asd )

	trace ( asd[i] );

for each ( var j in asd )

	trace ( j );	// will trace same as above

---

It might be worth noting that the private namespace is now truly private, subclasses won't be able to access it. protected is the equivalent of (AS2)private. When making your own classes for MCs in the library (or making your document class!) be sure to make them public! That one took me a while to figure out.. :/

I wonder if this thread will not become a copy and paste things from the as3 forum
for each vs for in, for example, is already covered in the senocular's tips of the day

In AS2 to change something in a MovieClip that is inside other clip you have to type his whole scope like

Code:

---

_root.MasterClip.blasterClip._x = 10;

---

In AS3, however,you can change it no matter where he is in the display list

Code:

---


var sp1:Sprite = new Sprite();
addChild(sp1);
var sp2:Sprite = new Sprite();
addChild(sp2);

var mc:MovieClip = new MovieClip();
mc.x = 10;
sp1.addChild(mc);
trace(mc.x);//10
sp1.removeChild(mc);
sp2.addChild(mc);
trace(mc.x);//10

---

In AS2, with this [] you can create objects dynamicaly, using for example, a String or a Number to define him.In AS3 you also can, but dont forget to put the scope behind of the []

Code:

---

var someString:String = "cat";
this[someString] = new Object();
this[someString].zp = 10;

trace(this[someString].zp);//10
trace(this.cat.zp)//10

---

Or, if you already have them created in the normal way, and a string should tell you wich one to use,you also can:

Code:

---

this[tellerString].x = 10;

---

However, those things are very slow, if you can use simple Arrays instead

@ Cimmerian: in previous AS languages one could easily create a shortcut like:

Code:

---

_root.MasterClip.blasterClip._x = 10;
bc = _root.MasterClip.blasterClip;
bc._x+=10;
trace("x: "+bc._x);//outputs 20

---

same can be done with as3 but slightly different:

Code:

---

var container:Sprite = new Sprite();
addChild(container);
var sprite:Sprite = new Sprite();
var sprite.name = "id_1";
container.addChild(sprite);
//now create a linkage
var winInstance:Sprite = container.getChildByName("id_1");
winInstance.x = 20;

---

True, but this is creating another object wich is another reference to the same space in the memory

humm...you edited after i posted...those are not the same things,however
this

Code:

---

_root.MasterClip.blasterClip._x = 10;
bc = _root.MasterClip.blasterClip;
bc._x+=10;
trace("x: "+bc._x);//outputs 20

---

Is creating another object wich is another reference for the same object
And this

Code:

---

var container:Sprite = new Sprite();
addChild(container);
var sprite:Sprite = new Sprite();
var sprite.name = "id_1";
container.addChild(sprite);
//now create a linkage
var winInstance:Sprite = container.getChildByName("id_1");
winInstance.x = 20;

---

Is returning another reference too, but will only work if the sprite was already a child of container,this way also it will not work anymore when you change his parent, for example
My previous point was that in AS3 you dont need references or parents to do this.I mean, to use getChildByName you have to know who is the parent, for dynamic content not always you will know it and sometimes it will not have any parent at all
Thats when you simply go
blaster.x = 20;
Without need to worry with references or parents

how to make your classes have acess to the former '_root'
Two ways to do this:

First one,( wich i will not use anymore)is pass a reference to
the stage when you create it or later
like

var something:so = new so(this);
or
something.stageReference = this;
When you declare something in the stage
Inside your class you have some object that will store that reference

I will not use this anymore, this was a dirty cheap quick fix that messes
with the constructor function and mess with everything and i dont like it

Now, another way is to use the Event
ADDED
This event is dispatched when a displayObjects adds something to his displayList
So, inside the stage you can put a function like this

Code:

---

stage.addEventListener("added", addedHandler);
function addedHandler(ev){
        ev.target.onAddedToStage();
}

---

ev.target is the object added.
And what it will do is to call a function onAddedToStage on a child
whenever any child is added
From the moment it is addChilded, your child class knows who is his .parent ,
Inside your child you will have to have this function,in wich you
do anything you want to do with your stage reference

Code:

---

function onAddedToStage(){
stageReference = this.parent;
//and you do what you want with it
stageReference.addEventListener("enterFrame", onEnterFrame);
}

---

There are other ways to do this, there is also an event onAddedToStage
wich not work in the f9 alpha, senocular also made a class to let your
childs know when they are added to anything...many ways

its important to use the correct number types ot achieve best performance.

The different number types are:

int
Number
uint

int - a 32-bit signed integer, or how i like to put it (numbers without decimals :)) they are good for loops, addition and subtraction and are faster than Number in these situations

Number - IEEE-754 double-precision floating-point number (number with decimals) it almost has the same speed as int in the loop, addition and subtraction department, but its much faster with multiplication and division because no conversion is required between the data types

uint - 32-bit unsigned integer, or positive whole Number. It is the slowest number type. I haven't found a good purpose for it yet. Adobe says that its good for ARGB and RGB color values, so i guess it is :)

so the two most common data types you'll probably use are Number and int when dealing with the mathematics in your games.

int is great for loops, addition and subtraction and bit shifting i.e >>, << because it deals with whole numbers. When the number can become a decimal/fraction it is automatically converted to the Number data type to deal with the operation. Then its converted back to int. Division and multiplication should be avoided also because the results will probably result in a fraction.

Code:

---

var n:int = 4
var i:int = 1

//fast
n++

//slow
i += .1
i += .6
i += .4
i += .3

trace(n, i) //5, 1

---

Number is the all-rounder, it performs well in all situations so should be used if you're unsure of what type to use.

So don't assume that because int doesn't require as much power to process than Number does that it will speed up any project, because little conversions can happen all over the place and might slow it down more than if you just used Number. Also remember than int will remove any decimal points in a Number, so realistic physics should always use the Number type, unless you are after unnatural movement.

hope it helps.

Quote:

---

Originally Posted by mr_malee

int is great for loops, addition and subtraction and bit shifting i.e >>, <<

---

I would like to know how to use those << >>

This killing the edit button sux
Anyway, IF your child will be removed from stage this
stageReference = this.parent;
will not work so its better to use something like

Code:

---

//(inside the class)
 //(inside the constructor function)
 hasStageReference = true;
 
 //outside constructor function, this is the function that receives the  //reference to the stage
 function setStageReference(obj){
  stageReference = obj;
 //do stage stuff
 stageReference.addEventListener("enterFrame", oef);
}

//on the stage 
stage.addEventListener("added", addedHandler);
function addedHandler(ev){
      if(ev.target.hasStageReference){
        ev.target.setStageReference(this);
}
}

---

I also dont like this way so much, maybe the best would be to use the correct onAddedToStage event, but i would rather wait for the new flash to use it

In earlier Flash versions "_name" property was direct access to objects, if you changed the _name object was only accessible with new name:

PHP Code:

---

mc1._name="mc2";
//traces undefined
trace(mc1); 
//traces mc2
trace(mc2); 


---

Not so in Flash 9. Like all properties, it has lost underscore and is now just "name".

First of, if you have objects placed directly on stage with F9, their name is locked and attempt to change it provides an error. Lets say movie clip is on stage with instance name mc1:

PHP Code:

---

//gives error
mc1.name="mc2"; 


---

You can still change name of objects created by code, but changing name property will not change the object itself:

PHP Code:

---

import flash.display.Sprite;
var mc1:Sprite = new Sprite();
mc1.name = "mc2";
trace(mc1);
//gives error for using undefined variable mc2
trace(mc2); 


---

So the "name" is just like some variable inside the object, changing it wont change the object itself.

All new display objects get default value assigned to name property when they are created, the default value is "instance+n" where n is number of childs on the current timeline:

PHP Code:

---

import flash.display.Sprite;
var mc1:Sprite = new Sprite();
//traces instance1
trace(mc1.name);
mc1.name = "mc2";
//traces mc2
trace(mc1.name); 


---

Whats the use of it then? You can use getChildByName() method which returns child with given name:

PHP Code:

---

import flash.display.Sprite;
var mc1:Sprite = new Sprite();
mc1.name = "mc2";
addChild(mc1);
//traces null
trace(getChildByName("mc1"));
//traces [object Sprite]
trace(getChildByName("mc2")); 


---

loadMovie, loadVariables, MovieClipLoader, LoadVars are all gone from Flash 9. Loader class loads swf files and images, URLLoader loads XML and variables, sounds are still loaded using sound class.

Lets look at Loader class.

PHP Code:

---

var ldr:Loader = new Loader();
var urlReq:URLRequest = new URLRequest("loadedmc.swf");
ldr.load(urlReq);
addChild(ldr); 


---

First you need to create new Loader object and new URLRequest object. Strings can not directly used, they must be converted into URLRequest. Once you have loader object, you can use load method to get extrenal file. Images and swf movies are loaded exactly same way.

Since loader is one of display objects, it can be added to stage directly without converting it into movie clip or image. However, you can not add childs to loader object.

Of course above example is not very good if the extrenal file is large and takes time to load. Luckily, loader class provides methods to know when content was successfully loaded:

PHP Code:

---

ldr.contentLoaderInfo.addEventListener (Event.COMPLETE, done);
function done (ev:Event):void {
    trace("completed loading");
} 


---

Notice that you can not add listeners directly to loader object, you have to add them into contentLoaderInfo object. That object also provides access to bytesLoaded, bytesTotal and other data in case you wish to show information about loading process.

Sometimes loading files may fail, maybe file was not found or connection was lost or for some other reason. It is good to check for error:

PHP Code:

---

ldr.contentLoaderInfo.addEventListener (IOErrorEvent.IO_ERROR, badthings);
function badthings (ev:IOErrorEvent):void {
    trace("loading went wrong");
} 


---

The loader object itself can be used to display stuff, but the actual image or movie it loaded is inside content object. For example if you loaded image and you want to access its bitmapData object, trying to get it from loader object gives an error:

PHP Code:

---

trace(ldr.bitmapData); 


---

instead, you use its content:

PHP Code:

---

trace(ldr.content.bitmapData); 


---

there is also the event progress, wich broadcast an event with the propertys bytesLoaded and bytesTotal, wich can be good to make a preloader

Code:

---

var re:URLRequest = new URLRequest("loaded_.swf");
var ld:Loader = new Loader();
ld.contentLoaderInfo.addEventListener("complete", ch);
ld.contentLoaderInfo.addEventListener("progress", pgHandler);
ld.load(re);
addChild(ld);
ld.y = 200;

function pgHandler(ev){
        trace(" bytesLoaded: " + ev.bytesLoaded + " bytesTotal: " + ev.bytesTotal);
       
}

function ch(ev){
        trace("complete!!");
}

---