## Trajectory & collision detection of multiple objects help

Apr 06 2006 | 3:08 pm
I've been trying to do some simple physics simulations using jit.gl.sketch, using 2 spheres rolling around, sort of simulating 2 balls on a pool table. Can anyone point me in the right direction of how to figure out the trajectory of the balls after colliding with each other? The collision detection is easy, but I can't figure out the math of how to bounce them in the proper direction after colliding. I've looked at the 'trajectory' patch from http://cicm.mshparisnord.net/dl/trajectory.htm but it's difficult to figure out what the heck is going on, as it's a very very thick patch. Has anyone on the list done anything like this they'd like to share? I'm interested in hitting or pushing one ball, calculating it's speed and angle, and applying that to the collision with another object to calculate the new trajectories of both objects, plus I'd like to add some real world variables, such as mass, friction, elasticity, and gravity.
Thanks!!!
Brian

• Apr 07 2006 | 9:41 am
The PMPD library will be your best friend!
http://www.maxobjects.com/?v=libraries&id_library=81& ;requested=PMPD&operateur=AND& id_plateforme=0
Originally made for PD, these objects have been ported for max (osX & win), but as most of help file are missing/unusable, and there are no example patches for max/jitter (there are help patches script-converted from PD patch. unclear and not very useful) I would really advice you to check the PD version first, (very easy, just open the doc/example/pmpd patches) justto understand how it works, and then try to patch in max.
(there are a couple of max example in Ali Momeni (osX) max port :< http://www.cnmat.berkeley.edu/%7eali/share/max/pmpd/pmpd-for -max.sit > http://www.cnmat.berkeley.edu/~ali/share/max/pmpd/pmpd-for-m ax.sit
And I can post a couple of patches that do the kind of thing you're looking for (spheres on a 2D pool table, with bounce, friction, attraction,.). as soon as I will have bought a new HD, reinstalled everything and restored my backup files. cause I had a terrible HD crash this morning!
You can have a look at this small video of a patch I made with PMPD objects:
Have fun with PMPD (I did!)
Mathieu Chamagne
www.maxobjects.com
• Apr 07 2006 | 2:11 pm
Thanks Mathieu! I was playing with that too by the way, but I wasn't sure where to begin.
I'd love to see some example patches.
Brian
• Apr 12 2006 | 9:35 am
Here is an example of using the great PMPD library (Physical modelling) in max/Jitter to simulate balls on a pool table (2d environment - collision / friction / gravity / attraction...)
Have fun !
Mathieu Chamagne http://mathieu.chamagne.free.fr www.maxobjects.com
• Apr 28 2006 | 5:19 pm
Hi Mathieu,
I've finally had a minute to check out your patch on your site. Very cool!!! Can I hire you to make a patch for me? I need something super simple, simpler than the patch (perhaps) you've already created.
Here is what I'm working on:
www.playoptix.com
What I need is to add ability to kick a ball or 3d object around, but have to ability (like your patch) to add gravity, so I can use this on a wall too. I would like to be able to have the spheres rotate in the direction they are rolling too. I would also like to apply various textures to the balls, or use other 3d objects that are imported, which could be anything from light bulbs, to logos, or 3d heads. What do you think??? Interested? Where are you located?
I'm working on this project with Peter Nyboer-I guess he is friends with Ali too. My Jitter knowledge is about at a moderate skill level to say the least. I'm better at making the stuff look good, than making it work properly.
Thanks!
Brian Dressel 773-398-2772
• Apr 28 2006 | 5:35 pm
Sorry list and Matthieu,
I accidently posted my last message to the list instead of Matthieu personally, but since it's out there, anyone interested in adding to the project, email me! brian@m1interactive.net
Thanks!
Brian