[Opensim-dev] Using ODE for vehicles and ragdolls

[Frisby, Adam]

Doesnt ODE have vehicle support internally? The concern I'd have about a vehicle layer over the top might be that performance is suboptimal since we need to run a second physics step which could introduce issues.

Regards,

Adam

> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
> bounces at lists.berlios.de] On Behalf Of Gerhard Dünnebeil
> Sent: Tuesday, 18 November 2008 10:40 PM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] Using ODE for vehicles and ragdolls
>
> Hi
>
> having looked into the ODE engine I don't think it's usable for the
> vehicle API.
>
> Instead i think we should put the vehicle engine on top of it.
>
> This is pretty easily done by adding another layer (could/should be in
> a
> plugin).
> It can be called in each "Simulate" step and calculate the forces
> needed
> to achieve the vehicles behaviour.
> These forces are then applied -- using the phys engine's API -- to the
> objects.
>
> This way we are
> a) ... independant (at least theoretically) from the characteristics of
> the underlying Phys engine
> b) ... able to implement different engines for different purposes
>
> I know someone (is it you, nlin?) already implemented a sailing boat in
> OpenSim. A modular approach here would allow us to implement
> alternative
> friction models beyond what LSL gives us.
>
>
> Just my two cents
>
> Gerhard
>
>
> nlin (message) wrote:
> > Hello,
> >
> > There's been some discussion about SL-compatible vehicles in OpenSim
> > recently, with its higher-level abstraction of how vehicles work.
> This
> > would have the long-term goals of compatibility and ability to swap
> > out physics engines while still using the same vehicle layer.
> >
> > SL-compatibility and abstracting vehicles from the physics engine are
> > good goals for the long term; sort of a top-down approach (start with
> > the vehicle abstraction, map it to many different physics engines).
> >
> > Complementary to this, I'd like to explore and start discussion of an
> > alternative way of handling vehicles by using a bottom-up approach.
> > Starting with the specific physics engine of ODE, can we use
> > ODE-specific features to make simple vehicles?
> >
> > I did some experiments with OpenSim and ODE and the answer seems to
> be
> > yes, we can make simple vehicles with ODE by using joints. We can
> also
> > make ragdolls. I posted some videos to YouTube of the preliminary
> results:
> >
> > http://www.youtube.com/watch?v=iYIh-eIwmjs
> > http://www.youtube.com/watch?v=z9bedzIuxdM
> >
> > This is only prototype work for now, put together sort of quickly as
> a
> > proof-of-concept with just enough "plumbing" (data flow) to work.
> > There are a number of issues that need to be solved for this to work
> > cleanly. As far as I know (please correct me if I'm wrong) there
> > hasn't been much work done to try to get ODE joints/vehicles/ragdolls
> > working in OpenSim, but I think it's an avenue worth exploring.
> >
> > Is there interest in pursuing this approach for OpenSim vehicles? I
> > would look forward to discussing some of the issues that would need
> to
> > be solved.
> >
> > Thanks,
> > N Lin (nlin)
> >
> > ---------------------------------------------------------------------
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