[ODE] Jitters

[Bob Dowland]

> Basically the *= -0.01 on each of the

shouldnt that be -= 0.01 ???

as in 

currentvalue -= 0.01 * currentvalue

because a straight mul by any -ve value is at least going to reverse direction - that's not going to give "gradual energy dissipation".

> -----Original Message-----
> From: Tim Rightnour [mailto:root at garbled.net]
> Sent: 08 November 2004 08:00
> To: ODE
> Subject: [ODE] Jitters
> 
> 
> Hello all,
> 
> I'm a new user to ODE, and am currently integrating it in my 
> open-sourced game
> ( http://www.genecys.org ).
> 
> After lots of fiddling, I got my simulation mostly stable, 
> and decided to try
> using WorldQuickStep instead of WorldStep to save CPU.  Right 
> now my simulation
> is basically a dTerrainY, and a few boxes sitting on it.
> 
> With WorldStep, within about 5-10 iterations of the loop, the 
> two objects
> settle out and sit still.  When I changed the code to use 
> quickstep, one of the
> objects settles out, but the other one jitters forever, 
> slowly rotating about
> the X and Z axes.
> 
> Reading the list archives, I decided to implement damping on 
> the bodies with
> the code that was posted earlier.  Basically the *= -0.01 on 
> each of the
> angular and linear velocity components.  Doing so instantly 
> caused my jittery
> object to explode off into space, regardless of if I was 
> using WorldStep or
> QuickStep.
> 
> I'm a bit confused what to do now.  I allready have ERP and 
> CFM set pretty
> leniently, as I don't care too much about squishiness:
> 
>     dWorldSetERP(mapg->world, 0.2);
>     dWorldSetCFM(mapg->world, 0.01);
> 
> Any advice would be appreciated.  I'm using ODE from CVS as 
> of today, with
> float precision.  Also, my stepsize is 0.05, which is about 
> as low as I'd like
> to take it, for performance reasons.  MAX_CONTACTS is set 
> around 30, and the
> box in question is generating about 5 (give or take during 
> jittering, but when
> stable it sits at 5).
> 
> ---
> Tim Rightnour <root at garbled.net>
> NetBSD: Free multi-architecture OS http://www.netbsd.org/
> NetBSD supported hardware database: 
http://mail-index.netbsd.org/cgi-bin/hw.cgi
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