[ODE] Re: ODE digest, Vol 1 #167 - 4 msgs

[David Jung]

>
> Subject:
>
> [ODE] new to the list
> From:
>
> "Bart van den Broek" <b.vandenbroek4@chello.nl>
> Date:
>
> Sat, 11 May 2002 21:21:53 +0200
> To:
>
> <ode@q12.org>
>
>
>Hi I am new to the mailing list.
>I plan to do something similar to what Karl Simms did some years ago.
>(check out: http://genarts.com/karl/evolved-virtual-creatures.html ).
>I am thinking to make all joints 100% non self intersecting though.
>
You might want to be careful.  I am using ODE and think that is it 
great, however, if I understand
Russ' goal with ODE correctly, it emphasizes speed over accuracy. 
 Consequently, it breaks many
laws of physics - such a conservation of energy.  For example, a freely 
rotating body in space, without
any damping (e.g. air resistance), will continuously gain angular momentum.
As Karl Sims quickly discovered himself, if you're doing evolution at 
this level - where the fitness
depends on the physics - a physics model that is as accurate as possible 
is paramount.
Evolution is great at discovering and exploiting the holes in the 
physics to the advantage of
the organisms (since that is what you're doing it for).
For example, you may find that despite your best efforts to combat it, 
that organisms continually
evolve that exploit the 'free energy' available in rotating bodies in 
increasingly ingenious ways.
You may have already considered this problem, but I thought it worth 
pointing out just-in-case.
Have fun evolving your creatures - and be sure to show us the results!
-David Jung.