Actionscript 3.0 Perfect Collision Detection registration point center? - actionscript-3

Question

hey i have a problem with Collision Detection i used this example from a website http://www.freeactionscript.com/2009/05/pixel-perfect-collision-detection/ but it only works when your Object's registration point is on the upper left corner what should i change in the code if let's say the registration point is on the center?
here is the code:
package
{
import flash.display.BitmapData;
import flash.display.DisplayObjectContainer;
import flash.geom.Matrix;
import flash.geom.Point;
import flash.geom.Rectangle;
public class CollisionTest
{
// vars
private var _returnValue:Boolean;
private var _onePoint:Point;
private var _twoPoint:Point;
private var _oneRectangle:Rectangle;
private var _twoRectangle:Rectangle;
private var _oneClipBmpData:BitmapData;
private var _twoClipBmpData:BitmapData;
private var _oneOffset:Matrix;
private var _twoOffset:Matrix;
/**
* Simple collision test. Use this for objects that are not rotated.
* #param clip1 Takes DisplayObjectContainer as argument. Can be a Sprite, MovieClip, etc.
* #param clip2 Takes DisplayObjectContainer as argument. Can be a Sprite, MovieClip, etc.
* #return Collision True/False
*/
public function simple(clip1:DisplayObjectContainer, clip2:DisplayObjectContainer):Boolean
{
_returnValue = false;
_oneRectangle = clip1.getBounds(clip1);
_oneClipBmpData = new BitmapData(_oneRectangle.width, _oneRectangle.height, true, 0);
_oneClipBmpData.draw(clip1);
_twoRectangle = clip2.getBounds(clip2);
_twoClipBmpData = new BitmapData(_twoRectangle.width, _twoRectangle.height, true, 0);
_twoClipBmpData.draw(clip2);
_onePoint = new Point(clip1.x, clip1.y)
_twoPoint = new Point(clip2.x, clip2.y)
if (_oneClipBmpData.hitTest(_onePoint, 255, _twoClipBmpData, _twoPoint, 255))
{
_returnValue = true;
}
return _returnValue;
}
/**
* Complex collision test. Use this for objects that are rotated, scaled, skewed, etc
* #param clip1 Takes DisplayObjectContainer as argument. Can be a Sprite, MovieClip, etc.
* #param clip2 Takes DisplayObjectContainer as argument. Can be a Sprite, MovieClip, etc.
* #return Collision True/False
*/
public function complex(clip1:DisplayObjectContainer, clip2:DisplayObjectContainer):Boolean
{
_returnValue = false;
_twoRectangle = clip1.getBounds(clip1);
_oneOffset = clip1.transform.matrix;
_oneOffset.tx = clip1.x - clip2.x;
_oneOffset.ty = clip1.y - clip2.y;
_twoClipBmpData = new BitmapData(_twoRectangle.width, _twoRectangle.height, true, 0);
_twoClipBmpData.draw(clip1, _oneOffset);
_oneRectangle = clip2.getBounds(clip2);
_oneClipBmpData = new BitmapData(_oneRectangle.width, _oneRectangle.height, true, 0);
_twoOffset = clip2.transform.matrix;
_twoOffset.tx = clip2.x - clip2.x;
_twoOffset.ty = clip2.y - clip2.y;
_oneClipBmpData.draw(clip2, _twoOffset);
_onePoint = new Point(_oneRectangle.x, _oneRectangle.y);
_twoPoint = new Point(_twoRectangle.x, _twoRectangle.y);
if(_oneClipBmpData.hitTest(_onePoint, 255, _twoClipBmpData, _twoPoint, 255))
{
_returnValue = true;
}
_twoClipBmpData.dispose();
_oneClipBmpData.dispose();
return _returnValue;
}
}
}

Answer 1

Well lets put it like this: How far away is the top left corner from the center point?
x += width * .5;
y += height * .5;
Right?
So if the code you posted above only treats it with top left (for whatever reason I don't know why) why not force it to treat it with center point instead?
Perhaps something like this?
_onePoint = new Point(clip1.x + _clip.width * .5, clip1.y + _clip.height * .5);
_twoPoint = new Point(clip2.x + _clip2.width * .5, clip2.y + _clip2.height * .5);