[AS3]as3中HitTest碰撞检测源代码实例

[AS3]as3中HitTest碰撞检测源代码实例

package  
{ 
         
        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 
        { 
 
                /* 
                    该方法返回 碰撞 true/false 
                */  
                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; 
                         
                        matrixmatrix.a = matrix.a / rootConcatenatedMatrix.a; 
                        matrixmatrix.d = matrix.d / rootConcatenatedMatrix.d; 
                        if( accurracy != 1 ) matrix.scale( accurracy, accurracy ); 
 
                        return matrix; 
                } 
 
        } 
 
}