[ODE] Constraint theorizing

[Henri Hakl]

Hmmm... I think you are right there.

However, I then still find it disturbing that 100x100 to 500x500 matrices
actually come into existence in practize for systems that aren't overly
complex.

pity... but thanks


----- Original Message -----
From: "Adam D. Moss" <adam@gimp.org>
To: <ode@q12.org>
Sent: Sunday, February 23, 2003 4:48 PM
Subject: Re: [ODE] Constraint theorizing


> Henri Hakl wrote:
> > I was just wondering, if there is a theoretical reason why all the
> > physics are computed into one giant contraint matrix.
> >
> > Consider the following simple generic case:
> >
> > The floor, and 2 boxes falling onto it. The boxes are quite far apart
> > and won't even come remotely close to touching each other.
> >
> > Instead of solving the constraints in one (for argument's sake) 20x20
> > matrix, why not use two 10x10 matrices that handle the boxes
> > seperately?
>
> This is pretty much what ODE does.
>
> >From section 3.2.1 in the manual:
> "Each island in the world is treated separately when the
> simulation step is taken. This is useful to know: if there
> are N similar islands in the simulation then the step
> computation time will be O(N)."
>
> An island is defined in the manual as a group of bodies connected
> via joints, though it should be noted that two or more islands can
> temporarily become a single larger island for the duration of a
> simulation step if contact joints have been created between them
> (~O(N^3) havoc then ensues).
>
> HTH,
> --Adam
> --
> Adam D. Moss   . ,,^^   adam@gimp.org   http://www.foxbox.org/   co:3
> busting makes me feel good
> kthx bye
> _______________________________________________
> ODE mailing list
> ODE@q12.org
> http://q12.org/mailman/listinfo/ode