Comments on: … wider range for displacementMapFilter

By: Alberto

Alberto — Tue, 03 Jun 2008 22:00:18 +0000

Yes, this way is a lot easier, but I have an image editor and -for project limitations- I need to use BitmapFilters.

I was thinking into extending the DisplacementMap filter or to create a whole new one but sincerely I don’t know how to begin.

Anyway thanks for your time and effort

By: pixelero

pixelero — Tue, 03 Jun 2008 19:06:50 +0000

Yes, having only 128 or 256 levels does cause the bands.
Btw, why does it have to be DisplacementMapFilter ?
If it’s only mirroring the stage, aren’t there some other ways of doing that, maybe BitmapData.draw(stage)?

var w:int = stage.stageWidth;
var h2:int = stage.stageHeight/2;

var reflectMap:BitmapData = new BitmapData(w,h2, true, 0×00); // half size again
// reflectMap.draw(stage); // or addEventListener…

var reflectBmp:Bitmap = new Bitmap(reflectMap);
reflectBmp.y = stage.stageHeight;
reflectBmp.scaleY = -1.0;
addChild(reflectBmp);

addEventListener(Event.ENTER_FRAME, enterFrame);

function enterFrame(e:Event):void {
reflectMap.fillRect(reflectMap.rect, 0×00); // this line is necesserly if animated with transparent parts

reflectMap.draw(stage);
}

By: Alberto

Alberto — Mon, 02 Jun 2008 19:02:41 +0000

In this example you use two displacementMaps for the same reason, isn’t it? But I’m using a class that (for project requirements) has to return a single BitmapFilter, so I can’t do an approach like yours…

Oh, i’m getting desperate right now…

By: Alberto

Alberto — Mon, 02 Jun 2008 18:47:58 +0000

Hi again,
I’ve tested the code and the result is the same as I could get; the image appears flipped but I think that only works for images smaller than 255. For bigger ones I see “bands” that aren’t flipped.

I’ve upload a sample:
http://www.theklue.com/test.png

I suppose that the problem is that we can’t detect more than 255 levels of the same color…

Have any clue?

Thanks again!

By: Alberto

Alberto — Mon, 02 Jun 2008 07:26:50 +0000

Lots of thanks pixelero! I will try it later.

I agree; with PixelBender this will a lot easier, but the problem is that I can’t use it in my project (I must use a BitmapFilter and, as you said , is very annoying – to say the least – to configure a displacementFilter to work “exactly”).

Will post the results.

Lots of thanks!!

Alberto

By: pixelero

pixelero — Sun, 01 Jun 2008 19:44:19 +0000

Ok, thanks for your comment.

Hint 1:
… as an example some code for reflecting upper half of the stage, MainTimeline, frame1:
// actionscript 3.0, code example // anything for drawing something on the stage addChild(something);


// dimensions of the stage

var w:int = stage.stageWidth;

var h2:int = stage.stageHeight/2; // half the stage height
// matrix for a vertical gradient

var gratrix:Matrix = new Matrix();

gratrix.createGradientBox(w, h2, // width,half the height,

						  Math.PI/2, // rad for 90 degrees

						  0, 0); // translate, in this case start from origin point
// temporary sprite for drawing the fill

var gradSprite:Sprite = new Sprite();

gradSprite.graphics.beginGradientFill(GradientType.LINEAR,

								[0x807F, 0x8000], // green constantly 0x80 - no replacement, blue transfers from 127 - the above pixel - to zero,

								[1, 1], // alphas, not significant

								[0x00, 0xFF], // ratios, linear fill

								gratrix );

gradSprite.graphics.drawRect(0,0,w, h2); // fill, half the stage size

gradSprite.graphics.endFill();
var displaceBmp:BitmapData = new BitmapData(w,h2,false); // half the stage, no alpha channel

displaceBmp.draw(gradSprite); // copy gradient fill to bitmapdata
var displacer:DisplacementMapFilter = new DisplacementMapFilter(

		displaceBmp,

		new Point(0,h2), // locates this filter below the horizontal middleline

		BitmapDataChannel.GREEN, // displacement in x-direction

		BitmapDataChannel.BLUE,	// displacement in y-direction

		0.0,4*h2); // scales, in this case only the blue component matters

this.filters = [displacer];

Hint 2:
I guess with PixelBender lots like this will be a whole lot easier: Adjusting displacementFilter for precise result can be a bit annoying, this tube view came out surprisingly well, but when I tried like a fish-lens or spherical effect, it did look good at all.

By: Alberto

Alberto — Sat, 31 May 2008 19:30:22 +0000

So interesting…. Thanks for this sample.

I’m trying to achieve a simple horizontal flip with the displacementmap filter but with no success. Basically I’m using a white-to-black gradient but I can’t get the flipped image. Can you give me any hint?

Lots of thanks in advanced.

Alberto