[ODE] Collision impact force

Adam Dershowitz dersh at alum.mit.edu
Tue Dec 21 10:04:49 MST 2004


It is somewhat physical.  When two things that are "springy" collide, then
the penetration depth is directly related to the impact force.  Maybe the
better way to describe it, rather than impact depth, would be deformation of
the contact surfaces.  So this model is as good as the assumption is that
any collision can be modeled with a spring compression.  Real impacts are
more complex, and not just linear springs, but this is fairly physical, and
probably not a bad approximation.

-- Adam




> From: Bob Dowland <Bob.Dowland at blue52.co.uk>
> Date: Tue, 21 Dec 2004 17:33:00 -0000
> To: Tyler Streeter <tylerstreeter at gmail.com>
> Cc: <ode at q12.org>
> Subject: RE: [ODE] Collision impact force
> 
> Sure thing! Although sadly I'm not likely to be trying in the very short term
> - I was just interested in hearing why you made that choice. I wouldn't have
> gone for pen depth because it's more of an artefact than a physical thing (as
> already mentioned). On the other hand, while using magnitude of impulse due to
> impact/friction seems like the obvious choice (in theory) it no doubt comes
> with an associated set of hassles.
> 
> There was a thread going not so long ago which threw up some interesting refs
> and analogues with fracture/breaking effects - I can dig it out if you're
> interested and/or missed it. Although those were more on the synthesis side
> rather than just volume control.
> 
> Bob.
> 
>> -----Original Message-----
>> From: Tyler Streeter [mailto:tylerstreeter at gmail.com]
>> Sent: 21 December 2004 16:25
>> To: Bob Dowland
>> Cc: stenyak at iespana.es; ode at q12.org
>> Subject: Re: [ODE] Collision impact force
>> 
>> 
>>> Tyler,
>>> 
>>> sounds like you've thought about this - what was wrong with
>> "the joint feedback way" aren't the reaction mags easy enough
>> to get hold of, too noisy, what gives - (?)
>>> 
>>> Bob.
>>> 
>> 
>> Actually, I haven't tried the joint feedback way.  I just happened to
>> try using the penetration depth first and never got around to using
>> the joint feedback structure.  If you do use the joint feedback to
>> adjust the sound volume, let me know how it goes.
>> 
>> Tyler
>> 
> 
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