[ODE] Stacking objects

Adam D. Moss adam at gimp.org
Mon Feb 23 20:13:59 MST 2004

Jeffrey Smith wrote:
> I've noticed that during normal, "happy" steps this error is between
> 10^-3 and 10^-1.  When stacking objects, however, this error shoots 
> up to 10^2 to 10^4.  Clearly, a bad thing.
> How can I reduce this error? 


 > Is there any way to do the step "more
> carefully"  (presumably with a higher cost) if I detect that the error
> is climbing? 

ODE's main idea of the amount of 'care' to take is mostly derived
from how short your timestep is.

 > Would fixing ODE to use doubles instead of floats for
>  dReals affect this?

Depends on where your error is 'coming from' (numerical
error vs contradictory constraints, etc), but double doesn't hurt.

 > Is there a more robust LCP solution technique
> that I could implement to fix this?

Not really... StepFast() is generally more error-prone, though
it does deal with certain uncommon types of stability problems
more gracefully than the standard solver (i.e. fighting

Adam D. Moss   . ,,^^   adam at gimp.org   http://www.foxbox.org/   co:3

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