[ODE] complete 3D Characters with physics?

[Dennis Jan Franken]

Hi,

many thanks for the input, so it`s seems to be 
better to use a box instead of a ground plane 
for manypedes?

Then it might be good if multiple box-box
contact points get implemented, that you
can still turn them off per object, to speed 
the simulation up.

I'm eager to do some experiments 
with our character soon, i`m really 
eager to see how it works, how 
animations like jumping and walking 
work, how to create a useful balancing
force, simulating close combat etc.

And i'll let go on that idea of simulating
really every toe, one for all toes will be
enough.
But i hope that one day this will be 
possible, and then many totally new 
games will finally be possible, like 
"Toe-Kungfu", or "Grab the nose with
the toes", or "Smack the toes" ;^)

Bye,
Dennis

>Message: 10
>Date: Tue, 12 Mar 2002 14:57:55 -0800 (PST)
>From: Nate W <coding@natew.com>
>To: "ode@q12.org" <ode@q12.org>
>Subject: Re: [ODE] complete 3D Characters with physics?
>
>On Tue, 12 Mar 2002, Dennis Jan Franken wrote:
>
>> Has anybody tried to simulate a fully articulated 3D Character with
>> ODE, and can give me some expirience?  That would mean simulating 22
>> bones minimum, or about 60 more with fingers and toes, using hinge
>> joints and ball and socket joints with rotation limits.
>
>I'm using a 1.4mhz Athlon and a GeForce 3.  I have not tried modelling a
>human form yet, but I have tried snakes and 'manypedes' with lots of
>joints.  
>
>I can get consistently good (realtime) performance from snakes with ~20
>bodies.  My snakes are made from chains of boxes connected with hinges.  
>When the boxes are touching the ground with their corners, performance is
>good; when many of the boxes have their sides contacting the ground,
>performance drops quite a bit.  Box-groundplane collision does not have
>the single-contact-joint shortcoming discussed earlier today (that's only
>a concern with box-box collision), so it's not unusual to get three ground
>contact points per box, and that ends up needing a lot of computing power.
>
>I have a 'manypede' generator (milliepede, centipede, manypede, right?),
>and each segment consists of two legs with three joints each, plus two
>central bodies with x- and y-axis joints to allow the critter to bend on
>both axes.  With four such segments, things start to slow below realtime.  
>That's ~32 joints and about as many bodies, plus a ground contact or two
>for each of the feet.
>
>I don't know if you've seen the MPEGs I mentioned earlier, but those
>simulations all run in real time, except maybe the 'dog.' That one I think
>is right on the edge of my computer's ability to run in real time.
>
>I should add that my application is configured so that the maximum
>'virtual elapsed time' between simulation steps is 15ms.  That's about 60
>frames per second.  As long as the ODE math gets done in 15ms, I get
>realtime simulations... if it takes longer, the simulation runs in
>Matrix/Max Payne "bullet-time." :-)  You could maybe go down to 40hz
>(25ms) without too much stability trouble, but I'm not sure.
>
>IIRC, the memory required for everything I've mentioned here is under 8
>megabytes.  Half that amount will work most of the time, but when a lot of
>boxes sit squarely on the floor, number of contact joints drives the
>memory requirement up sharply.
>
>> Is this reasonably possible with speed, stability and memory?
>
>My guess is that the 22-bone figure will probably work, but I'd hold off
>on the 60-bone fingers-and-toes approach for now.
>
>My suggestion is to simplify further still - just model feet, shins,
>thighs, a couple of spine segments, upper and lower arms, and a head.  
>That should almost guarantee some extra CPU power for things other than
>physical simulation.
>
>-- 
>
>Nate Waddoups
>Redmond WA USA
>http://www.natew.com


---
Dennis Jan Franken <djfranken@gmx.de>
Tel.: 030 78717138
ICQ: 1521523