PhysicsEngines

Revision as of 22:18, 10 September 2007

There are several physics engines available for use in OpenSim. Currently, they are "basicphysics", "OpenDynamicsEngine", "RealPhysX" & "Bulletx". The plugin "basicphysics" is the default and can be seen in the OpenSim.ini file.

• When starting OpenSim in either Windows or Linux, one can add -physics=OpenDynamicsEngine to run the OpenDynamicsEngine (ODE) instead of basicphysics, or change the corresponding parameter in OpenSim.ini.

• When starting OpenSim in Windows, one can add -physics=RealPhysX if one has the appropriate DLL's which are not shipped with OpenSim due to EULA constraints.

• When starting OpenSim in either Windows or Linux, one can add -physics=modified_BulletX to run a modified version of the BulletX Physics Engine aka Modified BulletX. See the next page about details and progress.

To conclude, basicphysics & OpenDynamicsEngine both are appropriate for Linux and in addition, RealPhysX is appropriate as an option for Windows if the supporting DLL's are available. Modified BulletX should be fine for Windows and Linux (not the original BulletX).

Compiling ODE from source (Linux)

If you want to compile the OpenDynamicsEngine (ODE) by yourself, get the latest source code (Ver. 0.8.1-rc1 as of 20070905) from http://www.ode.org/. Unpack it, switch to the ode directory and compile it as follows:

./configure --with-trimesh=gimpact --enable-shared
make -k

This should create a libode.a and lidode.so file in the src/ode subdirectory. Copy these two files to the opensim bin directory (after having backed up the original files there).

The above configuration parameters are the default as compiled for the libode that is shipped with OpenSim. You can also try to configure libode with: --with trimesh=opcode and/or --enable-double-precision (the latter may not work and may crash when starting OpenSim).