ex_35.tex

\documentclass[a4paper]{article}
\usepackage{pst-solides3d}
\pagestyle{empty}
\begin{document}
 
%@AUTEUR: Manuel Luque, Juergen Gilg
\psset{viewpoint=50 50 20 rtp2xyz,lightsrc=25 37 17,Decran=50,unit=0.75}
\begin{pspicture}(-3.5,-1)(3,15)
 
\pstVerb{
 /torsion {
2 dict begin
/M defpoint3d % on récupère les coordonnées
/AngleTorsion M 20 mul 3 -2 roll pop pop def
% on tourne de 10 degrés à chaque niveau
M 0 0 AngleTorsion rotateOpoint3d
end} def
}%
 
\psSolid[object=prisme,h=15,ngrid=20 6,
 base=1.5 0 1.5 1.5 0 1.5 -1.5 1.5 -1.5 0 -1.5 -1.5 0 -1.5 1.5 -1.5,
 transform=torsion,
 fillcolor=lightgray,
 incolor=lightgray,
 hollow,
 opacity=0.6
]%
\end{pspicture}
 
\end{document}