ex_3.tex

\documentclass[a4paper]{article}
\usepackage{pst-solides3d}
\pagestyle{empty}
\begin{document}
 
%@AUTEUR: Juergen Gilg
% \section*{Twister \dots}
\psset[pst-solides3d]{viewpoint=10 9 10,SphericalCoor,
	Decran=40,lightsrc=5 -5 5}
\begin{pspicture}(-6,-6)(-6,6)
\rput(0,0){
\defFunction[algebraic]{twister}(u,v){2*u/(u*u+v*v+1)}%
{(u*u+v*v-1)/(u*u+v*v+1)}%
{2*v/(u*u+v*v+1)}
\psSolid[object=surfaceparametree,
    base=2 neg  2  2 neg  2,
    linecolor={[cmyk]{1,0,1,0.5}},linewidth=0.75\pslinewidth,
    ngrid=50,
%    RotY=90,
    RotZ=-90,
    function=twister]%
}
\end{pspicture}
 
\end{document}