[ODE] Syncing ODE over a Network (client side prediction)

[Emmanuel Astier]

You must also have the same dt in order to have the same simulation.

Event with the same dt, two different processors can achieve different
results, because of rounding differences in the FPU.

On PC, you can set the rouding mode you want to have the same results on
Intel and AMD.

Hope it helps, 

Emmanuel

-----Message d'origine-----
De : ode-bounces at q12.org [mailto:ode-bounces at q12.org] De la part de Dave
Kerr
Envoyé : jeudi 1 décembre 2005 08:40
À : ode at q12.org
Objet : [ODE] Syncing ODE over a Network (client side prediction)

Hi, I'm building a multiplayer game engine and am trying to sync ODE objects

over a network.
All is fine if I sync static objects...
But with moving objects, the clients and server usually end up out of sync.
Ie the simulations rarely run the same course.

I was wondering if this is part of ODE (random numbers)?
Or am I missing some variables to sync:

When a client connects, they get Position, Linear Velocity, Angular 
Velocity, Mass, Density, Size/shape and the Quaternion
to 12 decimal places, of every body.
It works if all objects are resting (or at least looks like its working), 
but once a moving object is added, the simulations take different paths.
How many decimal places is necessary?
Am I missing some data?

I would like to minimize the network traffic by trusting the clients to 
correctly predict most of the ODE physics.

Any thoughts on this subject would be appreciated.

cheers,
Dave 

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