ActionScript 3

The Burning Man – bitmapData fire effect

Yesterday night it was too warm to sleep and I have no air conditioning at home, so I thought it was a good opportunity to make some experiments related to the high temperature… “the burning man” 😀

Here’s the algorithm in human language:
– pick up the image from the webcam
– perform a threshold on it to exclude (alpha 0) every pixel below the average skin amount of red (between 44 and 90 depending on the light)
– perform a second threshold to exclude (alpha 0) every pixel above the average skin amount of green and blue (between 3344 and 6677 depending on the light)
– draw the result onto a new bitmapdata with the ADD blendmode
– apply blur to the bitmapdata
– generate a perlin noise of one channel (i chose red)
– displace the bitmapdata towards -y
– apply again a displacement map filter to displace horizontally (i used a cos function to make the x displacement a little likely)
– apply a displacement map towards +y with just a bit less strenght than the previous “-y” one (this is to make the fire propagation much more likely)
– then merge the original webcam output with the displaced one…and you’ve the burning man! 🙂

here the actionscript implementation

	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.BitmapDataChannel;
	import flash.display.BlendMode;
	import flash.display.Sprite;
	import flash.filters.BlurFilter;
	import flash.filters.DisplacementMapFilter;
	import flash.filters.DisplacementMapFilterMode;
	import flash.geom.ColorTransform;
	import flash.geom.Matrix;
	import flash.geom.Point;
	import flash.geom.Rectangle;

	public class BurningMan extends Sprite

		private var _cam:Camera;
		private var _vid:Video;

		private var _fireThreshold:BitmapData;
		private var _firePerlin:BitmapData;
		private var _fireOffset:Point;
		private var _fireSpeed:int = 20;
		private var _fireDisplaceUP:DisplacementMapFilter;
		private var _fireDisplaceDWN:DisplacementMapFilter;
		private var _fireDisplaceSrc:BitmapData;
		private var _fireBlur:BlurFilter;
		private var _fireColorTransform:ColorTransform;

		private var _fireMerge:BitmapData;

		private var _camBd:BitmapData;
		private var _b:Bitmap;

		private static const WIDTH:Number = 320;
		private static const HEIGHT:Number = 240;
		private static const ORIGIN:Point = new Point();
		private static const REFLECT:Matrix = new Matrix(-1,0,0,1,WIDTH,0);
		private static const RESIZE_2X:Matrix = new Matrix(2,0,0,2);

		private var _rect:Rectangle;

		public function BurningMan()

		private function init():void
			_cam = Camera.getCamera();
			_vid = new Video(WIDTH,HEIGHT);

			_fireOffset = new Point();
			_fireThreshold = new BitmapData(WIDTH,HEIGHT,true,0x00000000);
			_fireMerge = new BitmapData(WIDTH,HEIGHT,true,0x00000000);

			_firePerlin = new BitmapData(WIDTH*.5,HEIGHT*.5,false,0x000000);
			_fireDisplaceSrc = new BitmapData(WIDTH,HEIGHT,false,0x000000);
			_fireDisplaceUP = new DisplacementMapFilter(_fireDisplaceSrc,ORIGIN,BitmapDataChannel.RED,BitmapDataChannel.RED,0,-15,DisplacementMapFilterMode.CLAMP);
			_fireDisplaceDWN = new DisplacementMapFilter(_fireDisplaceSrc,ORIGIN,BitmapDataChannel.RED,BitmapDataChannel.RED,0,9,DisplacementMapFilterMode.CLAMP);
			_fireBlur = new BlurFilter(2,2,4);
			_fireColorTransform = new ColorTransform(1.3,1.1,1,.7);

			_camBd = new BitmapData(WIDTH,HEIGHT,true,0x00000000);
			_rect = _camBd.rect;
			_b = new Bitmap(_camBd);


		private function update(e:Event=null):void



			_fireDisplaceUP.scaleX = Math.cos(((_fireOffset.y/(2<<3))%360)*180/Math.PI)*2;
			_fireDisplaceDWN.scaleX = -_fireDisplaceUP.scaleX;


here’s a preview of myself empowered by the force of the fire!:D
burning man
click the photo to see the demo in action


2 thoughts on “The Burning Man – bitmapData fire effect

  1. Hi, it looks nice, but it would like liner if I could view it, but I cant. I dont have any web camera. It wasn’t necessary to had one. Could you send me instructions how to change the code a little to launch it without camera?

  2. it’s quite simple,
    just remove all occurrencies of video and camera and put a reference to the image you want to apply the effect to within the update method (_camBd.draw(yourImage))

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