学步园

在坛里看到过有朋友贴过不规则物体碰撞检测的类，这里，我再贴个一位牛老外写的一个类，经自己测试，用一个1500*1500的矢量图和一个10*10的不短移动的小球进行碰状检测，CPU占用仅4%左右，超级高效！！！
这里是代码：
Actionscript:

CODE:

package ws.tink.display

{

 

	import flash.display.BitmapData;

	import flash.display.BlendMode;

	import flash.display.DisplayObject;

	import flash.display.Sprite;

 

	import flash.geom.ColorTransform;

	import flash.geom.Matrix;

	import flash.geom.Point;

	import flash.geom.Rectangle;

 

	public class HitTest

	{

 

		public static function complexHitTestObject( target1:DisplayObject, target2:DisplayObject,  accurracy:Number = 1 ):Boolean

		{

			return complexIntersectionRectangle( target1, target2, accurracy ).width != 0;

		}

 

		public static function intersectionRectangle( target1:DisplayObject, target2:DisplayObject ):Rectangle

		{

			// If either of the items don't have a reference to stage, then they are not in a display list

			// or if a simple hitTestObject is false, they cannot be intersecting.

			if( !target1.root || !target2.root || !target1.hitTestObject( target2 ) ) return new Rectangle();

 

			// Get the bounds of each DisplayObject.

			var bounds1:Rectangle = target1.getBounds( target1.root );

			var bounds2:Rectangle = target2.getBounds( target2.root );

 

			// Determine test area boundaries.

			var intersection:Rectangle = new Rectangle();

			intersection.x 		= Math.max( bounds1.x, bounds2.x );

			intersection.y		= Math.max( bounds1.y, bounds2.y );

			intersection.width 	= Math.min( ( bounds1.x + bounds1.width ) - intersection.x, ( bounds2.x + bounds2.width ) - intersection.x );

			intersection.height = Math.min( ( bounds1.y + bounds1.height ) - intersection.y, ( bounds2.y + bounds2.height ) - intersection.y );

 

			return intersection;

		}

 

		public static function complexIntersectionRectangle( target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1 ):Rectangle

		{			

			if( accurracy < = 0 ) throw new Error( "ArgumentError: Error #5001: Invalid value for accurracy", 5001 );

 

			// If a simple hitTestObject is false, they cannot be intersecting.

			if( !target1.hitTestObject( target2 ) ) return new Rectangle();

 

			var hitRectangle:Rectangle = intersectionRectangle( target1, target2 );

			// If their boundaries are no interesecting, they cannot be intersecting.

			if( hitRectangle.width * accurracy < 1 || hitRectangle.height * accurracy < 1 ) return new Rectangle();

 

			var bitmapData:BitmapData = new BitmapData( hitRectangle.width * accurracy, hitRectangle.height * accurracy, false, 0x000000 );	

 

			// Draw the first target.

			bitmapData.draw( target1, HitTest.getDrawMatrix( target1, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, -255, -255, 255 ) );

			// Overlay the second target.

			bitmapData.draw( target2, HitTest.getDrawMatrix( target2, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, 255, 255, 255 ), BlendMode.DIFFERENCE );

 

			// Find the intersection.

			var intersection:Rectangle = bitmapData.getColorBoundsRect( 0xFFFFFFFF,0xFF00FFFF );

 

			bitmapData.dispose();

 

			// Alter width and positions to compensate for accurracy

			if( accurracy != 1 )

			{

				intersection.x /= accurracy;

				intersection.y /= accurracy;

				intersection.width /= accurracy;

				intersection.height /= accurracy;

			}

 

			intersection.x += hitRectangle.x;

			intersection.y += hitRectangle.y;

 

			return intersection;

		}

 

 

		protected static function getDrawMatrix( target:DisplayObject, hitRectangle:Rectangle, accurracy:Number ):Matrix

		{

			var localToGlobal:Point;;

			var matrix:Matrix;

 

			var rootConcatenatedMatrix:Matrix = target.root.transform.concatenatedMatrix;

 

			localToGlobal = target.localToGlobal( new Point( ) );

			matrix = target.transform.concatenatedMatrix;

			matrix.tx = localToGlobal.x - hitRectangle.x;

			matrix.ty = localToGlobal.y - hitRectangle.y;

 

			matrix.a = matrix.a / rootConcatenatedMatrix.a;

			matrix.d = matrix.d / rootConcatenatedMatrix.d;

			if( accurracy != 1 ) matrix.scale( accurracy, accurracy );

 

			return matrix;

		}

 

	}

 

}

封装了3个静态方法，直接用传参调用即可！

算法值得学习。
这里是原文地址：http://www.tink.ws/blog/as-30-hittest