Multi-platform platformer

[Doneveno]

So I'm trying to learn AS3. I've already made what can barely be called a platformer (one-frame sprite moving around, rudimentary jumping engine). My problem is with having more than one platform. Right now I'm testing sprite/platform intersection with hitTestObject. This is all well and good, except for...well, here's an example:

if(!dude.hitTestObject(thing){
thing.x += 8;
}

This code checks to see if you're touching a thing, and if not, moves the thing 8 pixels right. That is to say, it's your "walking to the left" routine.

Experienced AS3-ers will already know my problem. I'd have to make a routine for EVERY SINGLE PLATFORM. No thanks. Naming all the platforms the same thing doesn't cut it, and making them all one movie clip just turns them into one giant, mostly invisible platform.

So what do I do? Is there some way I can incorporate that into a for loop and have like...thing.i.x += 8 instead?

[Diki]

Store all the platforms in an array (or an object if you're using OOP) and then just use a simple for loop:

for(i = 0; i < theArray.length; i++)
{
      if(!dude.hitTestObject(theArray[i])
      {
            thing.x += 8;
      }
}

That will loop once for every index in the array (i.e. once for every platform). The variable "i" will be equal to the current iteration of the loop.
This is very rudimentary and not really going to do what you want on its own, but the theory is there.

[Doneveno]

How would I go about storing them into an array in the first place?

[Diki]

The same way you stored them in their current variable.
Like in this example:

var theArray:Array = new Array();
theArray['guy1'] = new Sprite();
theArray['guy2'] = new Sprite();
theArray['guy3'] = new Sprite();

And so on like that.

[UnknownFury]

At 10/1/09 02:57 PM, Diki wrote: for(i = 0; i < theArray.length; i++)
{
if(!dude.hitTestObject(theArray[i])
{
thing.x += 8;
}
}

That's a horrible way to do it. Use hitTestPoint, or other form of more accurate collision detection than hitTestObject, and put all the platforms in one MC.

[hucki]

Just thought that I should point out that you did:
if(!dude.hitTestObject(theArray[i])

You missed out a ) at the end, resulting in a bracket left open.
What you need to do is:
if(!dude.hitTestObject(theArray[i]))

[Doneveno]

To test this application out, I made a little thing that creates a square when you push a button, nothing else. Code is as follows:

import flash.display.Sprite;
import flash.events.MouseEvent;
var button:MovieClip = new MovieClip();
var platformcontainer:Sprite = new Sprite();
var a:Number = 0;
var b:Number = 0;
var debugtext:TextField = new TextField();
var debugv:Number = 0;
var arrayfun:Array = new Array();
var i:Number = 0;
arrayfun['square1'] = new Sprite();
arrayfun['square2'] = new Sprite();
arrayfun['square3'] = new Sprite();
arrayfun['square4'] = new Sprite();
arrayfun['square5'] = new Sprite();

this.addChild(platformcontainer);
this.addChild(button);
this.addChild(debugtext);

button.graphics.lineStyle(3, 0x992222);
button.graphics.beginFill(0xAA1111);
button.graphics.drawRect(0, 0, 50, 50);
button.graphics.endFill();
button.x = 0;
button.y = 350;

button.addEventListener(MouseEvent.CLICK, makesquare);

function makesquare(e:Event):void{
	arrayfun[i].graphics.lineStyle(3,0x1111AA);
	arrayfun[i].graphics.beginFill(0x222299);
	arrayfun[i].graphics.drawRect(0,0,100,100);
	arrayfun[i].graphics.endFill();
	arrayfun[i].x = a;
	arrayfun[i].y = b;
	platformcontainer.addChild(arrayfun[i]);
	a += 5;
	b += 5;
	debugv++;
	i++;
}

debugtext.x = 100;
debugtext.y = 100;
addEventListener(Event.ENTER_FRAME, display_variable);
function display_variable(event:Event){
	debugtext.text = String (debugv + " " + a + " " + b + " " + platformcontainer.numChildren);
}

But it doesn't work. What did I do wrong?

[Doneveno]

Nobody?

[Diki]

You're not referencing the array properly.
You have:

arrayfun[i].graphics.lineStyle(3,0x1111AA);
	arrayfun[i].graphics.beginFill(0x222299);
	arrayfun[i].graphics.drawRect(0,0,100,100);
	arrayfun[i].graphics.endFill();
	arrayfun[i].x = a;
	arrayfun[i].y = b;
	platformcontainer.addChild(arrayfun[i]);

That is looking for arrayfun[0], arrayfun[1], arrayfun[2], et al, which are not initialized.
You want this:

arrayfun[i].graphics.lineStyle(3,0x1111AA);
	arrayfun['square'+i].graphics.beginFill(0x222299);
	arrayfun['square'+i].graphics.drawRect(0,0,100,100);
	arrayfun['square'+i].graphics.endFill();
	arrayfun['square'+i].x = a;
	arrayfun['square'+i].y = b;
	platformcontainer.addChild(arrayfun['square'+i]);

arrayfun['square'+i] will end up being arrayfun['square1'], arrayfun['square2'], et cetera.
However I didn't actually run the code so there in theory could be something else wrong with it.

[Diki]

Whoops, missed a line.
Proper code:

arrayfun['square'+i].graphics.lineStyle(3,0x1111AA);
	arrayfun['square'+i].graphics.beginFill(0x222299);
	arrayfun['square'+i].graphics.drawRect(0,0,100,100);
	arrayfun['square'+i].graphics.endFill();
	arrayfun['square'+i].x = a;
	arrayfun['square'+i].y = b;
	platformcontainer.addChild(arrayfun['square'+i]);

[Doneveno]

Ah, see, I'm used to C++ where array[0] means the first thing in an array. AS3 is the first language I've seen where you refer to things in an array by name. Thanks.

[kizza0]

you can use numbers aswell.

[Diki]

At 10/1/09 09:51 PM, Doneveno wrote: Ah, see, I'm used to C++ where array[0] means the first thing in an array. AS3 is the first language I've seen where you refer to things in an array by name. Thanks.

It's the same in AS3. However you can also refer to the arrays using keys that are strings, such as in the example I have you. However if you use the string keys to define the array like you did you must reference them the say way.

If you wanted to do it the same as C++ you can either just use numbers instead of "square#" or use arrayfun.push(value) which will add on an index to the end of the array, and can be referenced using the appropriate index number.

[blank0000]

Well I just go into whatever I have as a ground and manipulate the symbol to be a bunch of platforms.