Very Basic TileBased Collision Detection

programming flash
1

So I’ve never dealt with collision detection since I mostly have just made simple web-designs, apps, and things that just don’t make use of physics or anything like that.

But today I decided to fiddle with it a little and was pretty excited when I started out just using a square to move around with keys and so I made some walls to figure out some collision stuff.

And basically, I can’t move out of the wall once I collide. I know I could make it so when I collide the sprite backs off a few pixels, but it causes that jittery effect. So I was wondering is it possible to check for a collision before the block is animated?

I’ve searched online for a while, everything seems to be scripted for as2 and just isn’t what I’m looking for.

Below is my sloppy testCode on the stage just to get my bearings before I implement anything in classes. The two sprites in use are sloppily instanced named: person, wall.

import flash.events.Event;
import flash.events.KeyboardEvent;

stage.addEventListener(KeyboardEvent.KEY_DOWN, keyedDown);
stage.addEventListener(KeyboardEvent.KEY_UP, keyedUp);
this.addEventListener(Event.ENTER_FRAME, frameHandler);

var keyIsDown:Boolean = false;

var keyUP:Boolean = false;
var keyDOWN:Boolean = false;
var keyLEFT:Boolean = false;
var keyRIGHT:Boolean = false;

var speed:Number = 5;

function frameHandler(e:Event):void
{
    if (keyIsDown)
    {
        if (keyLEFT)
        {
            if (! this.person.hitTestObject(this.wall))
            {
                this.person.x -=  speed;
            }
        }
        if (keyRIGHT)
        {
            if (! this.person.hitTestObject(this.wall))
            {
                this.person.x +=  speed;
            }
        }
    }
}

function keyedDown(e:KeyboardEvent):void
{
    keyIsDown = true;
    switch (e.keyCode)
    {
        case 65 :
            keyLEFT = true;
            break;
        case 68 :
            keyRIGHT = true;
            break;
        default :
            break;
    }
}

function keyedUp(e:KeyboardEvent):void
{
    keyIsDown = false;
    
    keyUP = false;
    keyDOWN = false;
    keyLEFT = false;
    keyRIGHT = false;
}

Also to add onto my question.

What if I wish to check collisions on ‘barrier’ boolean propertied tiles? Like if I made impassable terrain, how does one check that for collisions on a wide scale?