These packages are used for the graphical user interface. You need
Tcl/Tk version 8.0 or newer and Tix version 4.1 (or newer ?). In most cases,
you have to install them before installing netgen. Tested versions of these
packages are available on 3rd
party libraries.
The header files are included from the netgen-file "ng4/ngtcltk/incvis.hh".
Eventually, you have to replace include<tcl.h> by include <tcl8.0.h>
etc.
Tcl/Tk and Tix requires *.tcl - files at runtime. Eventually you have
to set the environment-variables TCL_LIBRARY, TK_LIBRARY and TIX_LIBRARY
like
setenv TCL_LIBRARY /usr/local/lib/tcl8.2
Togl by
Brian Paul and Ben Bederson provides the link between Tcl/Tk and OpenGl
rendering. It requires internal tk-header files, which are included for
several tk-distributions (like tkInt8.0.h). If you use newer Tcl/Tk versions,
please copy the file "tkInt.h" (from the Tk-source directories) to the
togl directory (e.g. to tkInt8.2p2.h), and adapt togl.cc (about line nr
120).