Filter

先來看個as3支援的filter特效吧!!
http://sakri.net/technology/flash/flex/convolution_filter/ConvolutionFilterExplorer.html


每個displayObject都有filter property, 型態是Array, 預設值是null.

所以要對displayObject使用filter,
就需asign一個塞著filter的Array給它的filter屬性.
如:
<br />var blur:BlurFilter = new BlurFilter(5, 5, 3);<br />var filters:Array = new Array();<br />filters.push(blur);<br />sprite.filters = filters;<br />

比較簡易的寫法,如下:
<br />var blur:BlurFilter = new BlurFilter(5, 5, 3);<br />var filters:Array = [blur];<br />sprite.filters = filters;<br />

還有更簡潔的方式:
<br />sprite.filters = [new BlurFilter(5, 5, 3)];<br />

以上的方法, 是直接覆蓋掉原本sprite的filter array.
若是想要append新的filter至原本的filter array的話,
千萬不可以寫成下面這行:
mySprite.filters.push(blur);
因為flash並沒有監聽filter array, 所以array的內容有所變動時, 並不會觸發flash去執行它.

只有在filter array被assign時, flash才會重新執行array中的filter.
所以正確append filter array的方法如下:
<br />var filters:Array = sprite.filters;<br />filters.push(new BlurFilter(5, 5, 3));<br />sprite.filters = filters;<br />

也可以寫成
<br />sprite.filters = sprite.filters.concat(new BlurFilter(5, 5, 3));<br />


BlurFilter的prototype.
public function BlurFilter(blurX:Number = 4.0, blurY:Number = 4.0, quality:int = 1)
第三個參數是blur的次數.
也可以用BitmapFilterQuality來設置.
但是此參數較耗render資源,所以䀆量以設置前兩個參數來達到需要的blur強度.


demo: http://imlab.cs.nccu.edu.tw/~pie/Filter.swf
<br />/*<br />blur filter<br />*/<br />package redbug.draw<br />{<br /> import flash.display.Sprite;<br /> import flash.filters.BitmapFilterQuality;<br /> import flash.filters.BlurFilter;<br /> <br /> import redbug.object.UglyBoy;<br /> <br /> <br /> public class Filters extends Sprite<br /> {<br /> private var headPic1:UglyBoy;<br /> private var headPic2:UglyBoy;<br /> <br /> public function Filters()<br /> {<br /> init();<br /> }<br /> <br /> private function init():void<br /> {<br /> headPic1 = new UglyBoy();<br /> headPic2 = new UglyBoy();<br /> var originSprite:Sprite = new Sprite();<br /> var blurSprite:Sprite = new Sprite();<br /> originSprite.addChild(headPic2);<br /> blurSprite.addChild(headPic1);<br /> blurSprite.x =120;<br /><br /> addChild(originSprite);<br /> addChild(blurSprite);<br /><br /> blurSprite.filters = [new BlurFilter(1.5, 1.5, flash.filters.BitmapFilterQuality.HIGH)];<br /> }<br /> }<br />}<br /><br />