This is a slightly modified version of View3D 3.3. As with the original code, this version is in the public domain, and is made available without any warranty:

This software was developed at the National Institute of Standards
and Technology by employees of the Federal Government in the course
of their official duties.  Pursuant to title 17 Section 105 of the
United States Code this software is not subject to copyright
protection and is in the public domain. These programs are
experimental systems. NIST assumes no responsibility whatsoever for
their use by other parties, and makes no guarantees, expressed or
implied, about its quality, reliability, or any other
characteristic.  We would appreciate acknowledgement if the software
is used. This software can be redistributed and/or modified freely
provided that any derivative works bear some notice that they are
derived from it, and any modified versions bear some notice that
they have been modified.

Only two changes to the program have been made to compile with GCC (on platforms other than Windows):

1. The inclusion of conio.h in misc.c has been moved inside the #if statement so that it is not included for GCC.

2. A #define macro (named STRCMPI) is used to switch between strcmpi and strcasecmp depending upon the compiler.

It is likely (though it hasn't been tried) that these modifications will not be sufficient to compile the code with the MINGW compiler(s). The only other known issue that is that on Windows XP it will crash (or fail) in certain situations, particularly with larger input files. This appears to be a memory problem (probably in the temporary polygon memory setup), and disabling optimization sometimes helps.

Build files for make (one for Windows system and one for non-Windows systems) and scons are included. Your mileage may vary.