\documentclass[a4paper]{article}
\usepackage{pst-solides3d,pst-node,arrayjob,multido}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\pagestyle{empty}

\makeatletter
\def\psPoint{\def\pst@par{}\pst@object{psPoint}}
\def\psPoint@i(#1)#2{{% coordonnées cartésiennes
  \begin@ClosedObj
\pnode(!
    \tx@optionssolides
    SolidesDict begin
    #1
   3dto2d cm_1 exch cm_1 exch
   end){#2}%
   \end@ClosedObj
  }\ignorespaces%
}
\makeatother

\def\grille{% quadrillage du plan Oxy
\psPoint(-10 -10 0){A1}\psPoint(10 -10 0){A2}
\psPoint(10 10 0){A3}\psPoint(-10 10 0){A4}
\pspolygon*[linecolor=green!50](A1)(A2)(A3)(A4)
\multido{\ix=-10+1}{21}{%
    \psPoint(\ix\space -10 0){A}
    \psPoint(\ix\space 10 0){B}
    \psline(A)(B)}
\multido{\iy=-10+1}{21}{%
    \psPoint(-10 \iy\space 0){A}
    \psPoint(10 \iy\space 0){B}
    \psline(A)(B)}
    \psPoint(0 0 0){O}
    \psPoint(10 0 0){X}
    \psPoint(0 10 0){Y}
    \psPoint(0 0 10){Z}
    \psline[arrowsize=0.3,arrowinset=0.2,linecolor=blue]{->}(O)(X)
    \psline[arrowsize=0.3,arrowinset=0.2,linecolor=blue]{->}(O)(Y)
    \psline[arrowsize=0.3,arrowinset=0.2,linecolor=blue]{->}(O)(Z)
    \uput[r](X){\textcolor{blue}{$x$}}\uput[u](Y){\textcolor{blue}{$y$}}%
    \uput[r](Z){\textcolor{blue}{$z$}}\uput[u](O){\textcolor{blue}{$O$}}}

\author{JPV \& ML}
\title{tracteur}
\date{25 septembre 2\,006}
\begin{document}
\maketitle


\begin{center}
%%
\psset{unit=0.4}
\psset[pst-solides3d]{viewpoint=20 10 15,Decran=17,lightsrc=10 20 20,ngrid=2 20,RotY=90,color=gray!50}
\begin{pspicture*}(-7,-5)(8,10)
\grille
\psSolid[object=pneu,h=1,r1=2,r0=1,RotZ=30](-3,-4,2)
\psSolid[object=pneu,h=1,r1=2,r0=1,RotZ=30](3,-4,2)
\psSolid[object=pneu,h=2.5,r1=4,r0=3](-4,4,4)
\psSolid[object=pneu,h=2.5,r1=4,r0=3](4,4,4)
\end{pspicture*}
\hfill
\begin{pspicture*}(-7,-5)(8,10)
\psset[pst-solides3d]{viewpoint=20 10 10,Decran=17,lightsrc=10 20 20,ngrid=2 20,RotY=90}
\grille
\psSolid[object=pneu,h=1,r1=2,r0=1,RotZ=30,color=gray!50](-3,-4,2)
\psSolid[object=cube,a=2,color=red!80](0,-4,2)
\psSolid[object=pneu,h=1,r1=2,r0=1,RotZ=30,color=gray!50](3,-4,2)
\psSolid[object=pneu,h=2.5,r1=4,r0=3,color=gray!50](-4,4,4)
\psSolid[object=cube,a=5,color=red!50](0,4,4)
\psSolid[object=pneu,h=2.5,r1=4,r0=3,color=gray!50](4,4,4)
\end{pspicture*}
\end{center}
\end{document}
