This project is written as an extension module to Jack , the real time human simulation and ergonomics package written at the Center for Human Modeling and Simulation at the University of Pennsylvania [3]. Jack has been under development for 10 years, and is currently used in more than 110 sites around the world, including John Deere, Fiat, Rover, and the Israeli Ground Forces. It offers both a powerful set of geometric manipulation tools, and a user community that can benefit from the implementation of this system.
Jack provides the low-level user interface tools and graphics routines that are used by this project [2]. Geometric objects are defined as Psurfs. The psurf object simplifies use of the algorithm greatly, since it maintains associative information about the connectivity of vertices, faces, and edges automatically.
The module is written in C++, and is compiled into a dynamic shared object. This object is linked into a running Jack \ process when needed. It installs a menu for itself, and loads its commands into Jack 's command parser. Thus, functions provided by this module can be accessed through the user interface, or through the JCL and Lisp interfaces.
While the code developed for this project is not operating system-specific, Jack currently requires Silicon Graphics IRIX 5.x.