[ODE] Increasing number of particales changes physics

[Jacob Ole Juul Kolding]

Are you experiencing a similar problem with slowdown?
And by slowdown I don't mean that the app will simply run slower, for me the
slowdown seems to be exponential eventually leading to the app hanging and
not responding.

Another weird thing. Most of the time my particles (using spheres as geom)
wont acquire torque when colliding with the floor.
I have however seen torque being applied in some situations just before the
app dies. which can happen when exceeding 350 particles but also when i
increase the detail of the particle mesh (using cylinders right now) which
as far as I see shouldn't affect ODE since I'm not using trimesh?

/Jacob Kolding

On 8/12/06, Roland Kindermann <iyo at gmx.de> wrote:
>
> Hi,
> I work with particles too. I think it would be nice to have a Point
> Geometry (which only consists of one point) for particles. It would
> probably be faster than a small Sphere.
> Cheers,
> Roland Kindermann
>
> Jacob Ole Juul Kolding schrieb:
> > OK I have a fixed step time and that works fine.
> >
> > The next problem is when I enable collision (So that the particles
> > bounce against a floor). When the simulation has up to 350 particles it
> > seem to run smoothly and stable, but above 350 it will eventually suffer
> > a slowdown death causing the app to be unresponsive.
> >
> > I switched to HashSpace and set the category/collide bits so that the
> > particles should not collide with each other but only the floor.
> >
> > Is this a bottleneck?
> >
> > /Jacob Kolding
> >
> >
> > On 8/11/06, *Jon Watte* <hplus at mindcontrol.org
> > <mailto:hplus at mindcontrol.org>> wrote:
> >
> >     Correct. You need to use a fixed time step. Such as in
> >     http://www.mindcontrol.org/~hplus/graphics/game_loop.html
> >     <http://www.mindcontrol.org/%7Ehplus/graphics/game_loop.html>
> >
> >     Jacob Ole Juul Kolding wrote:
> >     >  I'm implementing a particle system in ODE and have encountered
> the
> >     >  problem that when the number of particles increase the physics
> change
> >     >  in the the way the even though the same force is applied, the
> more
> >     >  particles are in the simulation the longer they will travel.
> >     >
> >     >  My guess is that since i step the world each frame, when the
> frame
> >     >  rate drops the step time increase which changes the outcome of
> the
> >     >  simulation?
> >     >
> >     >  Anyone have an idea how to help this problem?
> >     >
> >     >  /Jacob Kolding
> >     >
> >
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