ActionScript 3 - Walls don't collide properly

For several weeks I'm been trying to make my topdown game. It went well for some time, but then at some point I wanted to create a scrolling map with walls everywhere. Now, to make it easy to create the map (and add more later) I made a class called "Wall" which I will hit test. This works, when it hits, the map must stop scrolling. It does, so good so far.

Now, when the player moves away from the object, I want the map to be able to scroll again, this works too, but now the player can't move to the side the player came from. I know this is because I need to define the sides, where the player enters, in order tell the game which movement must be set to zero at that point.

You can see the code here:

public function AddWalls(player:MovieClip)
{
    WallObjects = new Array();

    for (var i:int = 0; i < this.numChildren; i++)
    {
        var mc = this.getChildAt(i);

        if (mc is Wall)
        {
            var wallobj:Object = new Object();
            wallobj.mc = mc;

            wallobj.leftside = mc.x;
            wallobj.rightside = mc.x + mc.width;

            wallobj.topside = mc.y;
            wallobj.bottomside = mc.y + mc.height;

            wallobj.width = mc.width;
            wallobj.height = mc.height;

            WallObjects.push(wallobj);
        }
    }
}

public function EnableCollisionWithWalls():void
{
    for (var k:int = 0; k < WallObjects.length; k++)
    {
        //if (player.y > WallObjects[k].topside && player.y < WallObjects[k].bottomside && player.x > WallObjects[k].leftside && player.x < WallObjects[k].rightside)
        if (player.hitTestObject(WallObjects[k].mc))
        {
            if (player.x > WallObjects[k].leftside && player.x < WallObjects[k].leftside+15)
            {
                Lefthit = true;
                trace(DebugVar);
                DebugVar++;
                player.x = WallObjects[k].leftside;
                Scroll_x = 0;
            }
            else
                if ( player.x < WallObjects[k].leftside -1 || (player.y > WallObjects[k].leftside ))
                {
                    Lefthit = false;

                }

            if (player.hitTestObject(derp))
            {
                Lefthit = false;
            }
        }
    }
}

public function EnableMovement():void
{
    map.x += Scroll_x;
    map.y += Scroll_y;

    for (var i:int = 0; i < this.numChildren; i++)
    {
        var mc = this.getChildAt(i);
        if (mc is Wall)
        {
            mc.x += Scroll_x;
            mc.y += Scroll_y;
        }
    }
}

public function MovementKeysDown(move:KeyboardEvent):void
{
    var Speed:int = -5;

    switch (move.keyCode)开发者_StackOverflow中文版
    {
        case 37: // venstre knap
            Scroll_x = -Speed;
            break;

        case 38: // op
            Scroll_y = -Speed;
            break;

        case 39: // højre knap
            Scroll_x = Speed;
            if (Lefthit)
            {
                Scroll_x = 0;
            }
            break;

        case 40: // ned
            Scroll_y = Speed;
            break;

        default:
    }
}

public function MovementKeysUp(move:KeyboardEvent):void
{
    switch (move.keyCode)
    {
        case 37:
            Scroll_x = 0;
            break;
        case 38:
            Scroll_y = 0;
            break;
        case 39:
            Scroll_x = 0;
            break;
        case 40:
            Scroll_y = 0;
            break;
        default:
        }
    }

Might be some syntax errors (since I removed some code in this editor). You can see the current version here.

In this version the scroll keeps on going. I did come up with a "fix" for it, by check if the player was 1 pixel away from the movieclip, inside the hit test (which for some reason works, which I guess it shouldn't since it doesn't hit anymore) and then setting the Lefthit to false. However this is not a good solution and if you continue up or down away from the movieclip, you are still not able to go right anymore...

I've been baffled by this for a long time, so I thought it was about time I asked for help. I couldn't find anything on how to control movement in a top-down game, with a scrolling map + wall :/

---

The simplest (but not most resource friendly) solution (if you anyway have a single storage for walls) is iterating through the walls and instead of using the Flash default hitTest (I don't like the way it works since ActionScript 2) - just check the coordinates and if you see that there's going to be a collision on the next simulation step - handle it according to the game logic.

The most useful optimization for this algorithm is creating a filter/data structure for getting only walls that are near to the player and so can be affected to the test for collisions.