The Visualization Toolkit (VTK) is an open source, freely available software
system for 3D computer graphics, modeling, image processing, volume rendering,
scientific visualization and information visualization. VTK also includes
ancillary support for 3D interaction widgets, two and three-dimensional
annotation, and parallel computing. At its core VTK is implemented as a C++
toolkit, requiring users to build applications by combining various objects into
an application. The system also supports automated wrapping of the C++ core into
Python, Java and Tcl, so that VTK applications may also be written using these
interpreted programming languages.

You can enable a lot of optional features by passing variables to the script
(VAR=yes/no ./VTK.SlackBuild):

IMAGING=yes|no  (default: no)
MPI=yes|no      (default: no), requires openmpi
TCL=yes|no      (default: yes)
TK=yes|no       (default: yes)
VIEWS=yes|no    (default: no)
WEB=yes|no      (default: no), requires python-twisted
JAVA=yes|no     (default: no), requires jdk
PYTHON=yes|no   (default: yes)
QT=yes|no       (default: yes)
VTKQT5=yes|no   (default: no), requires qt5
