[ODE] ODE in Myst V: A Postmortem

[Colin Bonstead]

You're right Adam, I don't know why it happens either.  The only thing I 
can think of is if I'm setting a higher velocity on the avatar movement 
joint in those cases (and having the 'bullet through a piece of paper' 
thing pop up).  I have an on-screen graph I can bring up that will show 
me details about the velocity and that sort of thing, and according to 
that everything was working as usual during the penetration issues.  
It's certainly possible that it's something on my end though.

Really though, I'm just not a big fan of the whole ERP thing.  In Havok, 
if a collision couldn't be resolved in one step it would just give up 
and those objects would stop colliding.  That obviously wasn't the best 
solution, since in the cases where it did happen the avatar or a dynamic 
physical would just drop through the floor.  However, it was pretty rare 
that that would happen.  Supposedly in Havok 2 it resolves the collision 
in one step no matter what, but I can't vouch for that.

-----Original Message-----
From: Adam D. Moss <adam at gimp.org>
Sent: Wed, 22 Jun 2005 20:10:26 +0100
To: Colin Bonstead <colin at cyan.com>
Subject: Re: [ODE] ODE in Myst V: A Postmortem

Colin Bonstead wrote:
> Sorry, I wasn't really clear here.  I do run ODE at a fixed 100 Hz, 
but
> if more than 100 ms passes in a frame I'll clamp the amount I'm going 
to
> step total that frame to 100 ms.  So the ODE clock and game clock will
> move out of sync at that point.  As far as ODE knows though, every 
step
> is 10 ms.

In that case I can't really see how you got the symptoms you
describe (joint instability and missed collisions only at low
frame rates).  Any more info?

ta,
--Adam
--
Adam D. Moss   -   adam at gimp.org