[ODE] Particle/cloth/skeleton (was: Re: Choleski factorization)

[david@csworkbench.com]

I am proposing reordering the contact joint's Info2 structure (in the
GetInfo2 function), so that when a 3 DOF contact joint is created, it's
penetration dimension, now stored in the first row of J, c, lo, hi, etc.
is stored in the third row.  This makes simple, non-sliding collisions
(which I presume happens more often than sliding ones) faster in my
implementation by removing the refactorization step for them, and
shouldn't affect the LCP system, unless you assumed that the penetration
dimension would come before the friction dimensions at some point in the
LCP code.  While I'm in there, I think I might have a solution to the
powering into/away from joint limits problem that I'd like to try. 
There's no way to isolate the ordering change, though, short of reordering
them in the function... wasting the cycles I was trying to save.  It
probably won't make that big of a difference except in the most
pathological cases (block walls), but it might help a bit.  So I can
understand if you're protective of your code and would rather it stay like
it is.  Or is there some restriction on the order of the rows of the
Jacobian?

The separate files argument does make sense.  I'll take the variables I
added back out of the body class and implement them as an extra array.

I'll need upload access to CVS at some point.

Ah, yes, documentation.  I almost forgot.  I knew those 5 years of Honors
English would come in handy at some point...  They probably also explain
the length of most of my emails :)

David

>
>> Well, the iterated solver is basically finished, but I was hoping to
>> get an answer from Russ about changing the order of contact
>> constraints and whether that will mess anything up in the old solver
>> first....
>
> change the order how? are you proposing a change in the ODE core? or can
> this change be isolated to the new code?
>
> as to contributing your code ... if would be best if your new code is
> structured as separate source file(s) that can be put in the main src
> and include directories. that way we can keep separate CVS changelogs,
> you can edit your stuff in CVS without worrying about affecting anything
> else, etc.
>
> also ... don't forget to document your new functions! :)
>
> russ.
>
> --
> Russ Smith
> http://www.q12.org/
>
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