Spaceball Driver

VMD interfaces to the Spaceball in one of two ways; either by communicating directly with the Spaceball using built-in serial interface software, or vendor provided drivers. Unix and Mac OS X versions of VMD use the built-in serial Spaceball driver. At startup, VMD checks for the existence of an environment variable VMDSPACEBALLPORT. This environment variable must be set to the Unix device name of the serial port to which the Spaceball is attached. The serial port device permissions must be set to allow the VMD user to open the device for reading and writing. In typical usage, this usually requires performing a chmod 666 /dev/somettyname on the appropriate device as root. One restriction with the use of the built-in Spaceball driver is that only one VMD process may safely use the Spaceball at a time. If multiple VMD sessions are started on the same machine and all are set to open the Spaceball, it will behave very erratically.

The Linux and Windows version of VMD can use open source (e.g. spacenavd) or vendor-provided (SpaceWare) driver to communicate with SpaceNavigator, Magellan, or Spaceball devices via windowing system events. The window system drivers operate somewhat differently from the serial driver built into VMD. The window system driver software runs as a separate process from VMD and must be started and fully operational before VMD is run. At startup time VMD attempts to open the windowing system driver interface, displaying the success or failure of initialization as it occurs, with applicable diagnostic information. The windowing system driver provides detailed control over the sensitivity and configuration of the Spaceball, Magellan, or SpaceNavigator device. In order to use the Spaceball function keys with VMD the windowing system driver must be set to send button events as Function 1 and Function 2 at a minimum. Once set, it should be possible to cycle through the various VMD Spaceball operational modes as described below.