[ODE] obstacle course for vehicles

Eike Decker eike at cube3d.de
Tue Aug 7 05:10:50 MST 2007

I am not up to date with the very latest ODE version, but 10 boxes should not be
a performance problem. There's obviously something not well adjusted. 

Performance can be greatly improved:
* As far as I remember, the sample uses simplespaces - make sure you use
hashspaces if the objects can collide with each other (just want to make sure
that's the case ;))
* use quickstep(!)
* Chose a simulation step size between 30-100 fps, the less the better, however,
jittering objects or penetrating objects might occur then
* use autodisable wisely - it can even be improved if you put disabled objects
in a space where inter-object testing is disabled (really pays off if you have
about >100 objects)
* limit the number of contactjoints per object (<5)
* limit the iterations
* chose simple contacts (disable all bits that you don't need like softcfm/erp
* simulating soft joints is often less computational expensive than computing
stiff joints, which requires more iterations

All this leads to errors in your simulation (oscillating object, objects that
penetrate or tunnel each other)
* let the masses be of comparable size - avoid extreme differences like 1:100
* avoid huge differences in speed (rotation as well as movement)
* let the system lose energy (air drag is not simulated at all), i.e. damp the
velocity and rotating velocity of all objects each step you make with a small
factor (i.e. *.999)

That's my experience so far. I have created a few simulations that also include
quite lot's of objects, i.e. http://luxinia.de/index.php/Demos/CraneDriver so
it is definitly doable with ODE


> Hi again.
> I want my vehicle to face a range of different obstacles.
> The ramp in the buggy-example is a very easy example and
> easy to improve as well.
> But I also want to confront the vehicles with more difficult
> obstacles, e.g. debris. Therefore I created boxes with random
> dimensions and dropped them at random positions in front
> of the vehicle. Problem again: already 10 boxes are a big
> challenge for the performance. The idea of the debris clearly
> is, that the pieces influence each other as well as the vehicle,
> that way I can't put them in a space together.
> Any ideas how I could realize some nice challenging obstacles,
> which the vehicle at least reaches? (I mean concerning the
> simulation speed!)
> Regards,
> TZ
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