DisplacementMapFilter not showing up in flash

Question

I have a problem with creating and applying displacement maps filters on a container Sprite. The setup is like this

public class ExplosionManager
{
    [Embed...] // this is an image I tested, basically a spherical displacement
    private var explodeDisplaceAsset:Class;
    private var explodeDisplace:Bitmap;
    private var displacementFilters:Array = new Array();
    private var displacementMaps:Vector.<BitmapData> = new Vector.<BitmapData>();
    private var unusedFilters:Vector.<DisplacementMapFilter> = new Vector.<DisplacementMapFilter>();
    private var unusedMaps:Vector.<BirmapData> = new Vector.<BitmapData>();

    public function ExplosionManager(container:Sprite)
    {
         explodeDisplace = new explodeDisplaceAsset();
         container.filters = displacementFilters;
    }
    public function ExplodeAt(pos:Point, force:int) : void
    {
         var newDisplaceMap:BitmapData;
         var newDisplaceFilter:DisplacementMapFilter;
         if(unusedFilters.length == 0)
         {
             newDisplaceMap = new BitmapData(64,64,true, 0x808080);
             newDisplaceMap.draw(explodeDisplace);
             newDisplaceFilter = new DispalcementFilter(newDisplaceMap, pos, BitmapDataChannel.RED, BitmapDataChannel.GREEN, force, force);
         }
         else
         {
              newDisplaceMap = unusedMaps.pop();
              newDisplaceFilter = unusedFilters.pop();
              newDisplaceFilter.componentX = force;
              newDisplaceFilter.componentY = force;
              newDisplaceFilter.mapPoint = pos;
              newDisplaceFilter.mapBitmap = newDisplaceMap;
         }
         displacementMaps.push(newDisplaceMap);
         displacementFilters.push(newDisplaceFilter);
    }
}

I'm trying to make an adaptive object pool that reuses and creates filters as needed, my initial thought was that if I have about 2-3 explosions tops it'd be more efficient to have 2-3 filters that only get applied to a part of the scene rather than have one filter with a single big bitmap that gets updated every frame. The problem is that I can't see any displacement no matter what combination of parameters I try, is there something I'm doing wrong ?

PS: I'm sorry if the code has some typos, I'm not at my development machine right now, so I had to rewrite it, but from the algorithms' point of view that's exactly what I wrote.

Answer 1

It seems like you're assigning the array displacementFilters to the filters property within the constructor (at setup of the ExplosionManager). It then looks like you're adding and modifying filters within that array at a later date.

Unfortunately, changes made to the filters stored within the array you used as a source last time will not be applied to the object. This is because when you assign an array to filters, a copy of that array is actually created and used. From the documentation:

To modify an existing filter object, you must use the technique of modifying a copy of the filters array:

1. Assign the value of the filters array to a temporary array, such as one named myFilters.
2. Modify the property by using the temporary array, myFilters. For example, to set the quality property of the first filter in the array, you could use the following code: myFilters[0].quality = 1;
3. Assign the value of the temporary array to the filters array.

You will need to assign the updated displacementFilters array to filters whenever there are changes made.