Comments on: Collision Detection and Bounce Calculation using Colour Maps (part 1)

By: Drew

Drew — Thu, 07 Jan 2010 17:41:14 +0000

Thanks for the status update. Still eagerly (but patiently) waiting for part two!

By: swingpants

swingpants — Thu, 07 Jan 2010 17:33:32 +0000

Yes, the method is excellent for detecting collisions with pixel perfect accuracy. In terms of applying ‘bounce’ impulses: when it comes to cars you’d need to think about crumpling – will the car dent or break up causing the bounce impulse to be deflected somewhat. This method does give you an initial impulse – which is a starting point for you to then implement some bespoke bounce method.

Apologies to everyone – I promised a part 2 months ago and have yet to get around to it. Work commitments have kept me tied up. I do intend to do some more work on this in the very near future though.

By: Dave

Dave — Wed, 06 Jan 2010 20:42:52 +0000

thanks great tutorial, looking forward to part2 to see how you implemented this! would this method work for other objects other than a circle? say a car represented by a rectangle? cheers.

By: Neil

Neil — Thu, 24 Sep 2009 13:02:55 +0000

Really nice, hope you do get around to part 2 one day, maybe even a few method snippets to help others achieve this would be good.

Thanks for sharing.

By: swingpants

swingpants — Mon, 03 Aug 2009 13:21:52 +0000

I did some webcam apps a couple of years ago, and as flood fill is an efficient way of finding movement, it lends it self to colour map collision detection. I did the classic balls landing on head experiment, and rolling off when moved – worked brilliantly.

Apologies for not getting part 2 of the colour map article up yet. I got 1/2 way through it back in May but have been up against it workwise since then. I will finish and post asap – hopefully in the next few weeks.

By: Og2t

Og2t — Mon, 03 Aug 2009 10:45:15 +0000

Thanks for sharing, I will try it to detect collisions against the viewer’s head (using webcam).

By: swingpants

swingpants — Thu, 30 Jul 2009 15:12:44 +0000

Apologies for delay in reply. Been totally rushed off my code feet for what seems like months now.

Yes, the yellow pixels should be exactly 0xFFFFFF00. The blend modes are exact so if 0xFF0000 overlaps with 0x00FF00 the result is 0xFFFF00. Any gradiation can only be as a result of the map colours not being exact – or any anti-aliasing that may have occurred (if you are drawing your colour map in Photoshop – if this is the case output the colour map from PS as a GIF and reduce the colours to just the ones you need)

By: Lorenz

Lorenz — Wed, 22 Jul 2009 12:51:18 +0000

Hi, great tutorial.
there is a problem when finding the rectangle with getColorBoundsRect( 0xFFFFFFFF, 0xFFFFFF00);
becouse drawing on a bitmap it will create yellow pixels fading to white and they are not exactly 0xFFFFFF00 so as3 doesnt see them
how did you fix it?

By: Boris

Boris — Tue, 12 May 2009 16:06:10 +0000

Great one – can`t wait for part 2 !!!!!!!!!!!

By: Swingpants Collision Detection « Robert W. Stewart’s Blogolicious

Swingpants Collision Detection « Robert W. Stewart’s Blogolicious — Wed, 22 Apr 2009 21:43:18 +0000

[...] some AS3 Colour Map collision code at a blogger that goes by the name of ‘Swingpants’ here. Swingpants found a very simple way to reflect objects off any shape. I couldn’t wait for [...]