[ODE] iterative solver bugs

[Martin C. Martin]

Hi,

During the last phase of active development on the iterative solver, there
were a few bugs.  Does anyone know if these are still there?

david@csworkbench.com david at csworkbench.com 
Sun Mar 30 08:44:02 2003 

> I had a quick play with test_crash, and I see a problem where the buggy
> is slowly moving right from the outset with Dave's solver, whilst it
> stops completely with the original (as it should).  I can toggle between
> those behaviours.  This is before any input has been applied.

Yeah, I think that's pretty much the same problem.  The easiest way to
make the bug apparent is to turn the mu down pretty low and press 'a',
where the car is spinning it's wheels a lot.  It'll head off at almost a
45 degree angle.  It only spins when you brake hard (get it going fast
with 'a', then press space).  I think the problem has something to do with
the fact that I'm accumulating forces between each joint evaluation, but
I'm not updating the velocity.  Maybe that's keeping ERP from doing it's
job.  I'll let you know when I get that in.


david@csworkbench.com david at csworkbench.com 
Sun Mar 30 08:37:02 2003 

Yeah, I've got to get the Island creation code back in there to get the
same results as before with body disabling.  Hopefully I'll get a chance
to put that in there after church.

David

> ----- Original Message -----
> From: <david@csworkbench.com>
> To: <ode@q12.org>
> Sent: Friday, March 28, 2003 7:25 PM
> Subject: Re: [ODE] iterative solver: testing needed
>
>
>> Hmmm, I'm guessing your body_simulate_set function calls dBodyDisable
>> or dBodyEnable.... Yeah, I think I know where that bug is, but I doubt
>> it's related to my sliding bug.  I'll fix it when I get home tonight.
>>
>> David
>>
>> > david@csworkbench.com wrote:
>> >> Well guys, I need some help finding out why my car is spinning when
>> it stops in the iterative solver, so I'm releasing it for y'all to
>> play with.
>> >>  If you can help me define exactly what causes it, maybe I can
>> track
>> >> down
>> >> my bug.
>> >
>> > Hi!  Thanks for this.  Interesting.
>> >
>> > I've noticed one probably-simple bug, but it might not be related to
>> your problem.
>> >
>> > The bug is that bodies which are body_simulate_set(body, FALSE)
>> continue to have gravity (and possibly other forces) applied to them
>> and their positions thus updated every step.
>> >