Question

i got this script from this tutorial. I tried to convert it from AS2 to AS3, but it seems like the displacement filter is only applied once for some reason. After that, the bitmap isn’t updated …

    var myBitmap:BitmapData = new BitmapData(1000,600,false,0);
    var pt = new Point(0,0);
    var mpoint = new Point(0,0);
    var myDispl = new DisplacementMapFilter(myBitmap, mpoint,1,2,10,30);
    var myList = new Array();
    myList.push(myDispl);
    water_mc.filters = myList;
    var i = 1;
    this.addEventListener("enterFrame", perlin );

    function perlin(evt)
    {
        var filterList = water_mc.filters;
        var offset = new Array();
        offset[1] = new Object(); 
        offset[1].x = i * 15;
        offset[1].y = i/8 * 15;
        filterList.mapBitmap = myBitmap;
        myBitmap.perlinNoise(45,5,3,50,true,false, 7,true,offset);

        water_mc.filters = filterList;
        i++;
    }

Answer 1

You dont need to apply the filter everytime since you are not making any changes to the filter in the Enter_Frame Handler. Also the DisplacementMapFilter can be directly applied to your movieclip. I have made some code changes to the code you pasted.

//waterImage is a Bitmap Object. If you embed the object it will be a bitmap so no issues
// typecast it if necessary. If you use a loader to load your image, then you can get the bitmap
// using loader.content after the loader has done loading.
var mpoint = new Point(0,0);
var myDispl = new DisplacementMapFilter(null, mpoint,1,2,10,30);
waterImage.filters = [myDispl];
var i = 1;
this.addEventListener("enterFrame", perlin );

function perlin(evt)
{
    waterImage.bitmapData.perlinNoise(45,5,3,50,true,false, 7,true,[i*15,(i/8)*15]);
    i++;
}