2 thoughts on “Labs: Line-Of-Sight”

1. Hmm…a slightly less laggy way to test for collision might be to use bitmapdata:
   /**
   * Pixel Perfect Collision Detection
   * ———————
   * VERSION: 1.0.1
   * DATE: 8/23/2011
   * AS3
   * UPDATES AND DOCUMENTATION AT: http://www.FreeActionScript.com
   **/
   package utils
   {
   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;
   }

   }

   }
   Pardon me if I’m wrong about the lag, I’m still a noob at this.

   If you’re wondering how I knew you used hitTestPoint, I decompiled your SWF. Sorr yabout that .

2. This is an extremely old post, and I haven’t even touched Flash in the past 2 years I have moved on to iPhone development now.

   Thanks for your contribution regardless.
   Daryl