**JSV1.07 can only display tetrahedra and octahedra**.
However, you may add individual triangular polygons which would
form cubes, squares etc. for a VRML output. The problem in a
program like JSV is how to generate the polyhedra. This is a very
complex procedure even for simple polyhedra. Required are lists
with vertex coordinates for each facet and those vertices have to
be ordered in a certain way so that connecting them really
results in a polygon and not in self-intersecting lines. The
display of polyhedra in JSV is quite difficult, since JSV uses
actually 2D graphics only. In real 3D graphics everything, even
the spheres (atoms), cylindrical bonds, polyhedra etc. is
polygonized and the used 3D engine takes care of displaying
interpenetrating atoms, bonds, polyhedra etc. correctly. JSV uses
a simple painter's algorithm where one starts drawing from the
back towards the observer. This works quite fine if only
non-interpenetrating atoms and bonds are used (ball-and-stick
model). With polyhedra it gets difficult. In the painters
algorithm usually only those polygons are drawn, whose normals
face towards the observer, whereas the ones facing away would be
hidden by the visible polygons and don't have to be drawn. Of
course this works only if the polygons form closed polyhedra. If
you were to specify single individual polygons, that do not
belong to a closed polyhedron, you would see them appear and
disappear as you rotate the structure. In order to experience
real 3D you may view VRML files, which can be written by JSV.

Now back to the generation of polyhedra. Other programs
usually use a technique where a central atom, its ligands and
their distances from the center have to be specified. In that
case, however, you cannot generate polyhedra which have no
central atom (eg. empty tetrahedra, which occur frequently).
Thats why JSV uses a different approach. I wanted to allow also
empty polyhedra to be generated. Here is how it is done: You go
into the display mode * numbers*, so that
you can see all individual atom numbers (kind of a serial
number). Then you select the ones that are to form the vertices
of a tetrahedron/octahedron and make the corresponding entry in
the input file. Then you activate the change by selecting the
present number of unit cells from the menu

Well, when you activate the changes the following happens. From the specified vertices JSV calculates the center of gravity as a virtual central atom position (it does not matter if there really is an atom or not). Then the space group routines are used to find all equivalent positions for that imaginary "central atom". Then for each of those positions the surrounding atoms are searched for the ones which are equivalent to the specified vertices. Then the polygons are specified and the vertices ordered in a clock-wise fashion. This ensures that the polygons are visible when they face towards the observer. Otherwise they will not be drawn.

As mentioned in the helpfile for Menus
you may create individual polygons from the menu** [Option]
[add polygon]**. In any case I will try to improve this
whole matter of generating polyhedra in future updates.