as3碰撞检测

一个基于as3的碰撞检测类：三个参数（第一个对象:DisplayObject、第二个对象:DisplayObject、精度:Number），返回一个布尔值。。。

  1 package ws.tink.display
  2 {
  3     
  4     import flash.display.BitmapData;
  5     import flash.display.BlendMode;
  6     import flash.display.DisplayObject;
  7     import flash.display.Sprite;
  8     
  9     import flash.geom.ColorTransform;
 10     import flash.geom.Matrix;
 11     import flash.geom.Point;
 12     import flash.geom.Rectangle;
 13     
 14     public class HitTest
 15     {
 16 
 17         public static function complexHitTestObject( target1:DisplayObject, target2:DisplayObject,  accuracy:Number = 1 ):Boolean
 18         {
 19             return complexIntersectionRectangle( target1, target2, accuracy ).width != 0;
 20         }
 21         
 22         public static function intersectionRectangle( target1:DisplayObject, target2:DisplayObject ):Rectangle
 23         {
 24             // If either of the items don't have a reference to stage, then they are not in a display list
 25             // or if a simple hitTestObject is false, they cannot be intersecting.
 26             if( !target1.root || !target2.root || !target1.hitTestObject( target2 ) ) return new Rectangle();
 27             
 28             // Get the bounds of each DisplayObject.
 29             var bounds1:Rectangle = target1.getBounds( target1.root );
 30             var bounds2:Rectangle = target2.getBounds( target2.root );
 31             
 32             // Determine test area boundaries.
 33             var intersection:Rectangle = new Rectangle();
 34             intersection.x         = Math.max( bounds1.x, bounds2.x );
 35             intersection.y        = Math.max( bounds1.y, bounds2.y );
 36             intersection.width     = Math.min( ( bounds1.x + bounds1.width ) - intersection.x, ( bounds2.x + bounds2.width ) - intersection.x );
 37             intersection.height = Math.min( ( bounds1.y + bounds1.height ) - intersection.y, ( bounds2.y + bounds2.height ) - intersection.y );
 38         
 39             return intersection;
 40         }
 41         
 42         public static function complexIntersectionRectangle( target1:DisplayObject, target2:DisplayObject, accuracy:Number = 1 ):Rectangle
 43         {            
 44             if( accuracy <= 0 ) throw new Error( "ArgumentError: Error #5001: Invalid value for accuracy", 5001 );
 45             
 46             // If a simple hitTestObject is false, they cannot be intersecting.
 47             if( !target1.hitTestObject( target2 ) ) return new Rectangle();
 48             
 49             var hitRectangle:Rectangle = intersectionRectangle( target1, target2 );
 50             // If their boundaries are no interesecting, they cannot be intersecting.
 51             if( hitRectangle.width * accuracy < 1 || hitRectangle.height * accuracy < 1 ) return new Rectangle();
 52             
 53             var bitmapData:BitmapData = new BitmapData( hitRectangle.width * accuracy, hitRectangle.height * accuracy, false, 0x000000 );    
 54 
 55             // Draw the first target.
 56             bitmapData.draw( target1, HitTest.getDrawMatrix( target1, hitRectangle, accuracy ), new ColorTransform( 1, 1, 1, 1, 255, -255, -255, 255 ) );
 57             // Overlay the second target.
 58             bitmapData.draw( target2, HitTest.getDrawMatrix( target2, hitRectangle, accuracy ), new ColorTransform( 1, 1, 1, 1, 255, 255, 255, 255 ), BlendMode.DIFFERENCE );
 59             
 60             // Find the intersection.
 61             var intersection:Rectangle = bitmapData.getColorBoundsRect( 0xFFFFFFFF,0xFF00FFFF );
 62             
 63             bitmapData.dispose();
 64             
 65             // Alter width and positions to compensate for accuracy
 66             if( accuracy != 1 )
 67             {
 68                 intersection.x /= accuracy;
 69                 intersection.y /= accuracy;
 70                 intersection.width /= accuracy;
 71                 intersection.height /= accuracy;
 72             }
 73             
 74             intersection.x += hitRectangle.x;
 75             intersection.y += hitRectangle.y;
 76             
 77             return intersection;
 78         }
 79         
 80         
 81         protected static function getDrawMatrix( target:DisplayObject, hitRectangle:Rectangle, accuracy:Number ):Matrix
 82         {
 83             var localToGlobal:Point;;
 84             var matrix:Matrix;
 85             
 86             var rootConcatenatedMatrix:Matrix = target.root.transform.concatenatedMatrix;
 87             
 88             localToGlobal = target.localToGlobal( new Point( ) );
 89             matrix = target.transform.concatenatedMatrix;
 90             matrix.tx = localToGlobal.x - hitRectangle.x;
 91             matrix.ty = localToGlobal.y - hitRectangle.y;
 92             
 93             matrix.a = matrix.a / rootConcatenatedMatrix.a;
 94             matrix.d = matrix.d / rootConcatenatedMatrix.d;
 95             if( accuracy != 1 ) matrix.scale( accuracy, accuracy );
 96 
 97             return matrix;
 98         }
 99 
100     }
101 
102 }

一个例子：

代码如下：

 1 package
 2 {
 3     
 4     import flash.display.Sprite;
 5     import flash.events.MouseEvent;
 6     import ws.tink.display.HitTest;
 7     import flash.geom.Rectangle;
 8 
 9     public class ComplexIntersectionRectangle extends Sprite
10     {
11         
12         private var _circle0        : Sprite;
13         private var _circle1        : Sprite;
14         private var _hit            : Boolean;
15         private var _intersection    : Sprite;
16         
17         public function ComplexIntersectionRectangle()
18         {
19             super();
20             
21             initialize();
22         }
23         
24         private function initialize():void
25         {
26              
27             _circle0 = new Sprite();
28             _circle0.x = 50;
29             _circle0.y = 100;
30             _circle0.addEventListener( MouseEvent.MOUSE_DOWN, onCircleMouseDown );
31             draw( _circle0, 0xFFFFFF );
32             addChild( _circle0 );
33             
34             _circle1 = new Sprite();
35             _circle1.x = 250;
36             _circle1.y = 100;
37             _circle1.addEventListener( MouseEvent.MOUSE_DOWN, onCircleMouseDown );
38             draw( _circle1, 0xFFFFFF );
39             addChild( _circle1 );
40             
41             _intersection = new Sprite();
42             addChild( _intersection );
43             
44             _hit = false;
45             
46             stage.addEventListener( MouseEvent.MOUSE_MOVE, onStageMouseMove );
47             stage.addEventListener( MouseEvent.MOUSE_UP, onStageMouseUp );
48         }
49         
50         private function onCircleMouseDown( event:MouseEvent ):void
51         {
52             var circle:Sprite = Sprite( event.target );
53             circle.startDrag( false );
54         }
55         
56         private function onStageMouseMove( event:MouseEvent ):void
57         {
58             var intersection:Rectangle = HitTest.complexIntersectionRectangle( _circle0, _circle1, 5 );
59             var hit:Boolean = ( intersection.width > 0 && intersection.height > 0 );
60             
61             _intersection.graphics.clear();
62             if( hit )
63             {
64                 _intersection.graphics.beginFill( 0xFF0000, 0.5 );
65                 _intersection.graphics.drawRect( intersection.x, intersection.y, intersection.width, intersection.height );
66                 _intersection.graphics.endFill();
67             }
68             
69             if( hit != _hit )
70             {
71                 _hit = hit;
72                 var color:Number = ( _hit ) ? 0x00FF00 : 0xFFFFFF;
73                 draw( _circle0, color );
74                 draw( _circle1, color );
75             }
76         }
77         
78         private function onStageMouseUp( event:MouseEvent ):void
79         {
80             _circle0.stopDrag();
81             _circle1.stopDrag();
82         }
83         
84         private function draw( circle:Sprite, color:Number ):void
85         {
86             circle.graphics.clear();
87             circle.graphics.beginFill( color, 1 )
88             circle.graphics.drawCircle( 0, 0, 25 );
89             circle.graphics.endFill();
90         }
91     }
92 }
93