使WebCamera中运动物体燃烧起来

对于WebCamera的互动设计，一般而言是将WebCamera的视频绘制到Bitmap中，并应用各种滤镜从而生成各种各样的效果。Fire效果是个比较经典的示例，用到了一些滤镜。
源代码如下：WebCamera_Fire类

package{
	import com.quasimondo.bitmapdata.CameraBitmap;
	
	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.BlendMode;
	import flash.display.Sprite;
	import flash.display.StageAlign;
	import flash.display.StageScaleMode;
	import flash.events.Event;
	import flash.filters.BlurFilter;
	import flash.filters.ColorMatrixFilter;
	import flash.filters.DisplacementMapFilter;
	import flash.geom.Matrix;
	import flash.geom.Point;
	
	[SWF(width="960",height="545",backgroundColor="#000000",frameRate="31")]
	public class WebCamera_Fire extends Sprite{
		private var w:Number = 320;
		private var h:Number = 240;
		
		private var fire:BitmapData = new BitmapData(w,h,false,0);
		private var oldFrame:BitmapData;
		private var newFrame:BitmapData;
		private var blendFrame:BitmapData;
		
		private var adjust:BitmapData=new BitmapData(w,h,false,0xFF7C00);
		private var matrix:Matrix=new Matrix();
		private var pt:Point=new Point();
		
		private var blur:BlurFilter=new BlurFilter(7,7,1);
		/*
			redResult   = (0.33 * srcR) + (0.33 * srcG) + (0.33 * srcB) + (0 * srcA) + 0
 			greenResult = (0 * srcR) + (0 * srcG) + (0 * srcB) + (0  * srcA) + 0
 			blueResult  = (0 * srcR) + (0 * srcG) + (0 * srcB) + (0 * srcA) + 0
 			alphaResult = (0 * srcR) + (0 * srcG) + (0 * srcB) + (1 * srcA) + 0
		*/
		private var redFilter:ColorMatrixFilter=new ColorMatrixFilter([0.33,0.33,0.33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0]);
		/*
			redResult   = (0.8  * srcR) + (0.05  * srcG) + (0 * srcB) + (0 * srcA) + 0
 			greenResult = (0 * srcR) + (0.65 * srcG) + (0 * srcB) + (0 * srcA) + 0
 			blueResult  = (0 * srcR) + (0 * srcG) + (0.5 * srcB) + (0 * srcA) + 0
 			alphaResult = (0 * srcR) + (0 * srcG) + (0 * srcB) + (1 * srcA) + 0
		*/
		private var fireFilter:ColorMatrixFilter=new ColorMatrixFilter([0.8,0.05,0,0,0,0,0.65,0,0,0,0,0,0.5,0,0,0,0,0,1,0]);
		private var dmf:DisplacementMapFilter;
		
		private var camera:CameraBitmap;
		private var container:Sprite;
		
		public function WebCamera_Fire(){
			if(stage) init();
			else addEventListener(Event.ADDED_TO_STAGE,init);
		}
		
		private function init(e:Event = null):void{
			stage.align = StageAlign.TOP_LEFT;
			stage.scaleMode = StageScaleMode.NO_SCALE;
			initStage();
			
			camera = new CameraBitmap(w*2,h*2,25,true);
			addChild(new Bitmap(camera.bitmapData));
			
			oldFrame=fire.clone();
			newFrame=fire.clone();
			blendFrame=fire.clone();
			dmf=new DisplacementMapFilter(blendFrame,pt,1,2,7,-35,"clamp");
			
			container=new Sprite();
			addChild(container);
			var bitmap:Bitmap = new Bitmap(fire);
			bitmap.scaleX=bitmap.scaleY=2;
			container.addChild(bitmap);
			container.blendMode=BlendMode.ADD;
			
			var bmp1:Bitmap = new Bitmap(blendFrame);
			bmp1.x = 640;
			addChild(bmp1);
			var bmp2:Bitmap = new Bitmap(fire);
			bmp2.x = 640;
			bmp2.y = 240;
			addChild(bmp2);
		
			addEventListener(Event.ENTER_FRAME,onEnterFrame);
		}
		
		private function initStage():void{
			stage.align = StageAlign.TOP_LEFT;
			stage.scaleMode = StageScaleMode.NO_SCALE;
		}
		
		private function onEnterFrame(e:Event):void{
			// 使用Difference混色模式将运动的轨迹保存到blend中
			blendFrame.draw(oldFrame);
			newFrame.draw(camera.bitmapData,new Matrix(0.5,0,0,0.5));
			oldFrame.draw(newFrame);
			blendFrame.draw(newFrame,matrix,null,BlendMode.DIFFERENCE);
			
			// 将blendFrame中运动轨迹的颜色调整成0xFFCCCCCC
		 	blendFrame.applyFilter(blendFrame,blendFrame.rect,pt,redFilter);//先调红些
			blendFrame.threshold(blendFrame,blendFrame.rect,pt,">",0x190000,0xFFCCCCCC,0x00FF0000,false);//将红色通道大于0x190000的颜色调整成0xFFCCCCCC
			blendFrame.applyFilter(blendFrame,blendFrame.rect,pt,blur);//应用模糊
			
			// 使用ADD模式将blendFrame的内容绘制到fire中
			fire.draw(blendFrame,matrix,null,BlendMode.ADD);
			
			// 生成噪波
			blendFrame.perlinNoise(13,10,1,Math.random()*100,false,true,3,false);
			blendFrame.draw(adjust,matrix,null,BlendMode.DARKEN);
			
			// 使fire向上置换
			fire.applyFilter(fire,fire.rect,pt,dmf);
			fire.applyFilter(fire,fire.rect,pt,fireFilter);//使fire逐渐减弱
		}
	}
}

原始的WebCamera视频内容：

火效果视频：