复杂的碰撞检测 工具类

  
package com.easyasrpg.implement.algorithm
{
       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
       {
              /**
               *复杂的碰撞检测
               * @param target1
               * @param target2
               * @param accurracy
               * @return
               *
               */          
              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;
              }
         }
 }