[ODE] Step Sizes

Jon Watte hplus-ode at mindcontrol.org
Wed Nov 3 10:13:23 MST 2004

It's likely that something's wrong in your program, or that 
you're using some specific piece of code that's not well supported. 
The only obvious one I can think of is the cylinder geom, although 
trimesh to trimesh collisions aren't great, either (especially not 
for concave trimeshes). Trimesh to anything else, and anything 
else to anything else, has always worked well for me.

FWIW, I use 1/100 second step size, and it's very stable. There's 
no popping, disapparance, or anything like that that I haven't 
traced to issues with my own code. I use dWorldQuickStep().

Reduce your code to just a few items that reproduce the problem 
you're seeing, and trace through it in the debugger, looking at 
all the values involved. It helps greatly if you build ODE from 
source for this, of course.

Yes, this probably means spending 20 minutes in the debugger on 
a single world step of your test case. That's the fate of a 
simulation developer. Just be glad you don't have to do it in a 
distributed system :-)


			/ h+

-----Original Message-----
From: ode-bounces at q12.org [mailto:ode-bounces at q12.org]On Behalf Of Donny
Sent: Wednesday, November 03, 2004 9:54 AM
To: ode at q12.org
Subject: [ODE] Step Sizes

Perhaps this is my own fault, but I didn't see anywhere a good step 
size for dWorldStep. I'm using ODE in a fixed-frame game, running at 30 
FPS, so originally I set the step size for 1/30. I recently tried 
adjusting this to see if it would make my simulation more stable (you 
know, the vanishing, jittering, and occasional popping that occurs.) I 
adjusted it from 1/30 to 1/300. The simulation actually got MUCH WORSE 
with more popping and vanishing.

What the hell? I'd have thought if ANY change were made by giving ODE 
more granularity, it would be that the simulation would become MORE 


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