[Opensim-dev] Prospective ODE physics changes

[Melanie]

Hi,

On 02/01/2012 21:51, Justin Clark-Casey wrote:
> I'm thinking of making two ODE related changes.
> 
> 1) Replace the current ODE libraries in OpenSimulator with ones compiled using the older GIMPACT collider instead of 
> OPCODE.  This is to address ODE crashes in simulators with more than one region as detailed in [1] and [2].  These don't 
> appear to occur with GIMPACT.

I'm not happy with that as a general decision. We should, if
anything like that is done, include both versions to give users the
choice. The OPCODE should remain the default in order to not
jeopardize existing setups and the GIMPACT libs can be copied in by
those experiencing the bug.
Many people don't run multiregion at all and would see only
downsides if this were done.

> 2) Reducing contacts_per_collision in [ODEPhysicsSettings] from 80 to something much lower, maybe even 1.  In my own 
> testing, reducing this number can halve scene physics time.  Normal avatar operations, such as standing on prims or 
> walking up ramps appear to be unaffected even at 1.  However, more testing is probably needed to arrive at a compromise 
> number.

This would greatly affect scripts using physics. I believe the
optimum would be 16-20, which would ensure that the scripting
maximum (16) collision contacts are always available.

Melanie