[Opensim-users] Several problem on scripting and physics

[Justin Clark-Casey]

On 12/08/10 10:33, Tzu-Lun Wong wrote:
> Hi all, I've posted this on the OSgrid technical forum and was
> redirected here.
>
> I'm currently working on a project for an University on exploring
> opensim as a possibility for a learning environment for physics. I've
> encountered several problem on my local opensim region. (NOTE: all
> problem below are encountered on the ODE physics engine)
>
> 1) Sometimes when object are set physical, it'll treat other object as
> "phantom". For example, I've set up a platform (8m x 6m x 0.1m) floating
> in mid air, and a lot of the time when I try to place anything physical
> on it, the physical object will ignore the platform and fall through it.
> I can't seen to find out why as I have tried various shapes and sizes
> and the problem isn't consistent, sometime it doesn't fall through
> sometime it does.

Does it also treat the avatar as phantom?

Just in case, you might want to try the latest git Master code, since I recently put in a fix that stops non-root prims 
being 'phantom' on initial shift-copy in-world duplication (though things are fine after a server restart).  I suspect 
that this doesn't have anything to do with your problem but it's worth checking.

As a last resort you may want to fiddle with the [ODEPhysicsSettings] section in OpenSim.ini, though I've no real idea 
if this will help.

>
> 2) When restarting my opensim server/region, all the object's script
> disappears. This means I have to save everything into my inventory
> before I close down the server and then rez them back and relocate them
> EVERY TIME. Is this a known problem or is there a step where I missed
> that will save the script before I quit the server?

In prim scripts should be being saved without any extra user actions.  I suggest you carefully check your OpenSim 
configuration.

>
> 3) This one is probably unsolvable unless there's an update on physic
> engine. My partner on the same project made a pendulum that pivot on a
> triangular shape. When the pendulum reaches it's highest peak on it's
> swing, it shakes vigorously. After a long time the pendulum will
> eventually shift position. I'm guessing this is due to rounding
> calculation on the contact point of the pivot point when it reaches it's
> highest peak, causing the pendulum to "shift-slightly" causing it to
> "shake".

I suspect you're right, though I'm no physics expert.  OpenSim currently uses ODE 10.1.  Some folks are experimenting 
with ODE 11.1 with good results.  I updated the OpenSim wiki at

http://opensimulator.org/wiki/PhysicsEngines

with those instructions (I haven't actually tried this myself).

Regards,

-- 
Justin Clark-Casey (justincc)
http://justincc.org
http://twitter.com/justincc