\documentclass{article} \usepackage{pst-solides3d} \begin{document} \pagestyle{empty} \newcommand\SectionPneu{ /m {90 4 div} bind def /Scos {m cos 2 m mul cos add 3 m mul cos add} bind def /Z0 {h 4 div} bind def /c {Z0 Scos div} bind def /Z1 {Z0 c m cos mul add} bind def /Z2 {Z1 c m 2 mul cos mul add} bind def /R1 {R c m sin mul sub} bind def /R2 {R1 c m 2 mul sin mul sub} bind def /R3 {R2 c m 3 mul sin mul sub} bind def R h 4 div neg % 1 R h 4 div % 2 R1 Z1 % 3 R2 Z2 % 4 R3 h 2 div % 5 r h 2 div % 6 r h 2 div neg % 7 R3 h 2 div neg % 8 R2 Z2 neg % 9 R1 Z1 neg % 10 } \begin{pspicture*}(-5,-6)(5,7) \psframe(-5,-4)(5,7) \psset[pst-solides3d]{SphericalCoor,viewpoint=50 20 20,Decran=25,lightsrc=10 20 20} \psSolid[object=grille,base=-10 10 -10 10,fillcolor=red!10](0,0,0) \psSolid[object=anneau,section=\SectionPneu,fillcolor=red!50!yellow!30,h=10,R=6,r=0.1](0,0,5) \psPoint(0,0,10){Z} \psPoint(0,0,12){Z'} \psline[arrowsize=0.3,arrowinset=0.2,linecolor=blue]{->}(Z)(Z') \uput[u](Z'){\textcolor{blue}{$z$}} \end{pspicture*} \end{document}