\section{One- and two-sided solids}

The contour of \Lkeyword{face} is defined in the plane $Oxy$ by
\begin{verbatim}
\psSolid[object=face,base=x1 y1 x2 y2 x3 y3 ...xn yn](0,0,0)%
\end{verbatim}
The edge of \Lkeyword{face} is defined in the plane $Oxy$ by the coordinates
of its vertices, given in counterclockwise order by the parameter \Lkeyword{base}:


\clearpage
\subsection{Triangular \texttt{`faces'}}

\begin{LTXexample}[width=6.5cm]
\psset{unit=0.4}
\psset{viewpoint=50 -20 30 rtp2xyz,Decran=50}
\begin{pspicture}(-5.5,-4.5)(7,3.5)
\psSolid[object=grille,base=-4 6 -4 4,action=draw,linecolor=gray](0,0,0)
\psSolid[object=face,fillcolor=yellow,action=draw*,
  incolor=blue,biface,base=0 0 3 0 1.5 3,
  num=all,show=all](0,1,0)
\psSolid[object=face,fillcolor=yellow,
  action=draw*,incolor=blue,
  base=0 0 3 0 1.5 3,num=all,
  show=all,biface,RotX=180](0,-1,0)
\axesIIID(0,0,0)(6,6,3)
\end{pspicture}
\end{LTXexample}


\subsection{\texttt{`face'} defined by a function}
\begin{LTXexample}[width=7.5cm]
\psset{unit=0.45}
\psset{viewpoint=50 -20 30 rtp2xyz,Decran=50}
\def\BASE{0 10 360{/Angle ED 5 Angle cos dup mul mul % x
 3 Angle cos 3 exp Angle sin mul mul } for}% y
\begin{pspicture}(-7,-5.5)(9,6)
\defFunction[algebraic]{F}(t){5*(cos(t))^2}
   {3*(sin(t))*(cos(t))^3}{}
\psSolid[object=grille,base=-6 6 -6 6,action=draw,linecolor=gray](0,0,0)
\psSolid[object=face,fillcolor=magenta,action=draw*,
  incolor=blue,biface,RotZ=90,
  base=0 2 pi mul {F} CourbeR2+](0,0,0)
\psSolid[object=face,fillcolor=yellow,action=draw*,
  incolor=blue,biface,
  base=0 2 pi mul {F} CourbeR2+](0,0,0)
\psSolid[object=face,fillcolor=yellow,action=draw*,
  incolor=blue,biface,RotY=180,
  base=0 2 pi mul {F} CourbeR2+](0,0,0)
\psSolid[object=face,fillcolor=yellow,action=draw*,
  incolor=red,biface,RotY=180,RotZ=90,
  base=0 2 pi mul {F} CourbeR2+](0,0,0)
\axesIIID(0,0,0)(6,6,5)
\end{pspicture}
\end{LTXexample}



\endinput