The GLE Tubing and Extrusion Library is a graphics application
programming interface (API). The library consists of a number of "C"
language subroutines for drawing tubing and extrusions. The library is
distributed in source code form, in a package that includes
documentation, a VRML proposal, Makefiles, and full source code and
header files. It uses the OpenGL (TM) programming API to perform the
actual drawing of the tubing and extrusions.

WWW: https://linas.org/gle/
     https://sourceforge.net/projects/gle/