Hi, Slothman, Welcome to Xith3D

.
You're trying to tun Xith3D on Linux, right? JOGL needs native libraries (just as SWT, LWJGL and JOAL), if you want to use them. You need to setup an appropriate classpath.
The Linux version of JOGL needs a file named jogl_drihack.so, which is not needed in the Windows version.
How are you compiling? Eclipse, NetBeans, ANT? I suppose, it is NetBeans (The SVN project is correctly setup to compile and run on Linux). Plase make sure (however this goes), that in NetBeans the Native Library location for the jogl.jar is setup to point to the linux subfolder of the jogl folder under third-party.
Marvin