Comments on: Pixel-Perfect Collision Detection in ActionScript3

By: fede

fede — Fri, 19 Feb 2010 15:51:01 +0000

Great, works like a charm

By: indiemaps.com/blog » Building topology in Flash

indiemaps.com/blog » Building topology in Flash — Wed, 13 Jan 2010 05:28:15 +0000

[...] game developers have often relied on a pixel-level bitmap test for overlap. As described in an article by Troy Gilbert, It’s pretty straightforward: you render two display objects to separate color channels, [...]

By: Davide

Davide — Mon, 21 Dec 2009 08:19:21 +0000

Hi Gilbert,

great class. I would encourage you to continue the development of the class. I tried the CDK class too. Both are great. I encounter problems when i use large object.
Please update your class with other feature.

Best regards
Davide

By: Valmaster Flash

Valmaster Flash — Sun, 25 Oct 2009 18:26:04 +0000

Hi Troy,

Magic script. I’m building a platformer right now and this code is a fundamental building block. Credit where credit’s due when it’s complete.

By: sakthivel

sakthivel — Tue, 29 Sep 2009 05:32:39 +0000

hi nice script with a comfortable coding.why you using the difference to draw a second image

By: Sean

Sean — Wed, 15 Jul 2009 16:32:22 +0000

Aezon, the functions in the class are static which means they are not within the instance of the class. Just call it like this colDetect.isCollising();

By: Sean

Sean — Wed, 15 Jul 2009 02:07:32 +0000

Hi I am using your collision detection and it works great with one execption. The white space is still being used in the collision detection. The pictures have been scaled down from the original size and are rotating at the time of collision. Does that matter, here is the line I am calling it from

CollisionDetection.isColliding(objOne,objTwo,s.stage,true,0.000001)

it is obviously in an if statement, but the contents of the statement shouldn’t affect why its not working. The variable s is the parent container of both objects to the best of my knowledge. The number that you see 0.000001 is the only number I can use to get a true anything larger then that or if the amount = 1 does not return true. If the amount = 0 then it collides but the objects are not visibly touching.

Thanks in advance.

By: Aezon

Aezon — Mon, 13 Jul 2009 02:19:42 +0000

I am having a problem with your code, I am trying to implement it as shown:

(I renamed the class colDetect, it is easier to type.)

var test:colDetect = new colDetect();

var tester:Boolean =test.isColliding(cursor,test1,stage);
trace(tester);

And it throws this error:

1061: Call to a possibly undefined method isColliding through a reference with static type colDetect.

I have examined this, and perhaps it is a simple mistake, but I don’t see how it would throw this error. Please Help.

By: Troy

Troy — Tue, 23 Jun 2009 20:09:42 +0000

Looks like the code was copied incorrectly, that line in your code should read:

public static function getCollisionPoint(target1:DisplayObject, target2:DisplayObject, commonParent:DisplayObjectContainer, pixelPrecise:Boolean = false, tolerance:Number = 0):Point

Looks like the blog is converting code to emoticons… sorry!

By: Anonymous

Anonymous — Tue, 23 Jun 2009 19:49:39 +0000

… it says i have a 1084: Syntax error: expecting rightparen before oint.
public static function getCollisionPoint(target1:DisplayObject, target2:DisplayObject, commonParent:DisplayObjectContainer, pixelPrecise:Boolean = false, tolerance:Number = (0) oint