%% 
%%  A DANTE-Edition example
%% 
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\setlength\parindent{0pt}

\usepackage{pst-solides3d}

\begin{document}
\psset{viewpoint=20 60 20 rtp2xyz,
  lightsrc=10 15 7,Decran=20}
\pstVerb{
  /verform {
    4 dict begin   % keep local
    /M defpoint3d  % save as vector
    /a .5 def /b 1 a 3 sqrt mul sub def
    /k M norme3d a mul b add def
    M k mulv3d
  end
  } def
}%
\begin{pspicture}(-3,-4)(3,3)
\psset{linewidth=.02,linecolor=gray}
\psSolid[object=cube,a=3,ngrid=9,
    transform=verform]%
\end{pspicture}
\end{document}