[pstricks] pst-solides3d

[Herbert Voss]

Just for fun:

\listfiles
\documentclass[pstricks]{standalone}
\usepackage{pst-solides3d}
\begin{document}

\def\A{3.0}
\def\B{0.5}
\begin{pspicture}(-3.5,-3.5)(3.2,13)
\psset[pst-solides3d]{viewpoint=20 -20 30 
rtp2xyz,Decran=15,lightsrc=viewpoint}
\defFunction[algebraic]{shell}(u,v)%
    {\A*cos(u)*sin(v)}%
    {\A*sin(u)*sin(v)}%
    {\A*(cos(v)+ln(tan(v/2))) + \B*u}
\psSolid[object=surfaceparametree,
   linecolor={[cmyk]{1,0,1,0.5}},
   base=0 pi 8 mul  0.1 2, fillcolor=yellow!50,
   incolor=green!50, function=shell, linewidth=0.5\pslinewidth,ngrid=100 
50]%
\end{pspicture}
\end{document}