\section{Definition of grating}

The user can specify the \Index{grating} of the solid with the option
\Lkeyword{ngrid} within the command \Lcs{psSolid}.

For the objects
\Lkeyval{cube},
\Lkeyval{prisme},
\Lkeyval{prismecreux},
the syntax is \Lkeyword{ngrid}=$n_1$ where $n_1$ represents the number of vertical \Index{gridlines}.

For the objects
\Lkeyval{cylindre},
\Lkeyval{cylindrecreux},
\Lkeyval{cone},
\Lkeyval{conecreux},
\Lkeyval{tronccone},
\Lkeyval{troncconecreux},
%%\verb+tore+,
the syntax is \texttt{\Lkeyword{ngrid}=$n_1$~$n_2$} where $n_1$ is an integer greater or equal
to  1 ($2$ for \Lkeyval{tore}) representing the number of the vertical gridlines, and $n_2$ is an integer
representing the number of divisions on the circle.

For the object
\Lkeyval{sphere},
the syntax is \texttt{\Lkeyword{ngrid}=$n_1$~$n_2$} where $n_1$ is an integer, representing the number of divisions on the vertical axis, and
$n_2$ is an integer representing the number of divisions on the circle
horizontally.

For the object
\Lkeyval{tore},
the syntax is \texttt{\Lkeyword{ngrid}=$n_1$~$n_2$} where $n_1$ and $n_2$
are integers.

Here are some examples:

\subsection{The cube}

\begin{center}
\psset{unit=0.4}
\begin{pspicture}(-7,-7)(7,7)
%\psframe(-7,-7)(7,7)
\psset[pst-solides3d]{viewpoint=50 40 20,Decran=50,lightsrc=10 10 10}
\psSolid[a=8,object=cube,ngrid=4,fillcolor=yellow]%
%\psSolid[a=8,object=cube,linewidth=2pt,action=draw]%
\psPoint(0,0,0){O}
%\uput[r](O){$O$}
\psPoint(0,0,4){Ak}
\psPoint(0,0,8){Az}
\uput[u](Az){$z$}
\psPoint(4,0,0){Ai}
\psPoint(8,0,0){Ax}
\uput[u](Ax){$x$}
\psPoint(0,4,0){Aj}
\psPoint(0,8,0){Ay}
\uput[dr](Ay){$y$}
\psPoint(4,-4,0){A1}
\psPoint(4,4,0){A2}
\psPoint(-4,4,0){A3}
\psPoint(-4,-4,0){A4}
\uput[dr](Ay){$y$}
%\psline[linestyle=dashed](O)(Ai)
%\psline[linestyle=dashed](O)(Aj)
%\psline[linestyle=dashed](O)(Ak)
\psline[linecolor=green,arrowsize=2mm,arrowinset=0.2]{->}(Aj)(Ay)
\psline[linecolor=blue,arrowsize=2mm,arrowinset=0.2]{->}(Ai)(Ax)
\psline[linecolor=red,arrowsize=2mm,arrowinset=0.2]{->}(Ak)(Az)
\psdot[linecolor=green](Aj)
\psdot[linecolor=blue](Ai)
\psdot[linecolor=red](Ak)
\end{pspicture}
\hfill
\begin{pspicture}(-7,-7)(7,7)
%\psframe(-7,-7)(7,7)
\psset[pst-solides3d]{viewpoint=50 45 10 rtp2xyz,Decran=40,lightsrc=30 45 0}
\psSolid[a=8,object=cube,ngrid=3,fcol=\colorfaces,RotY=45,RotX=30,RotZ=20]%
\end{pspicture}
\end{center}


For the first example, the grid is fixed to $4\times4$
facettes/faces and the command is the following:
\begin{verbatim}
\psSolid[a=8,object=cube,ngrid=4,fillcolor=yellow]%
\end{verbatim}
In the second example, the face grid is set to $3\times3$
and the colours of the faces are different.
We use the package
\texttt{arrayjob} to easily save the colours:
\begin{verbatim}
\newarray\colors
\readarray{colors}{%
    Apricot&Aquamarine%
    etc.}
\end{verbatim}
The list of the colours is given by the command:
\begin{verbatim}
\edef\colorfaces{}%
\multido{\i=0+1}{67}{%
    \checkcolors(\i)
    \xdef\colorfaces{%
    \colorfaces\i\space(\cachedata)\space}
     }
\end{verbatim}
One sets up:~\Lkeyword{fcol}\verb+=\colorfaces+.
The gridded cube now is called with:
\begin{verbatim}
\psSolid[a=8,object=cube,ngrid=3,%
        fcol=\colorfaces,
        RotY=45,RotX=30,RotZ=20]%
\end{verbatim}
The option \Lkeyword{grid} suppresses the drawing of the gridlines.


\subsection{Sphere}

\begin{LTXexample}[width=6cm]
\begin{pspicture}(-3,-3)(3,3)
\psset{viewpoint=50 50 20 rtp2xyz,Decran=50,lightsrc=viewpoint}
\psset{color1=cyan,color2=red}
\psSolid[
   fcol=251 (OliveGreen) 232 (color1) 214 (color2),
   object=sphere,
   ngrid=16 18,
   RotX=180,RotZ=30]%
\end{pspicture}
\end{LTXexample}

\begin{LTXexample}[width=6cm]
\begin{pspicture}(-3,-3)(3,3)
\psset{viewpoint=50 50 20 rtp2xyz,Decran=50,lightsrc=viewpoint}
\psset{color1=cyan,color2=red}
\psSolid[
   action=draw*,
   fcol=0 (OliveGreen) 2 (color1) 3 (color2),
   object=sphere,
   ngrid=4 4,
   RotX=180,RotZ=30]%
\end{pspicture}
\end{LTXexample}

\subsection{Cylinders}

\begin{LTXexample}[width=6cm]

\begin{pspicture}(-3,-4)(3,4)
\psset{viewpoint=50 50 20 rtp2xyz,Decran=50,lightsrc=viewpoint}
\psset{color1=cyan,color2=red}
\psSolid[
   fcol=0 (OliveGreen) 2 (color1) 3 (color2),
   h=5,r=2,
   object=cylindrecreux,
   ngrid=4 30,
   RotZ=30
](0,0,-2.5)
\end{pspicture}
\end{LTXexample}
%
\begin{LTXexample}[width=7cm]
\begin{pspicture}(-3,-4)(4,4)
\psset{viewpoint=50 50 20 rtp2xyz,Decran=50,lightsrc=viewpoint}
\psset{color1=cyan,color2=red}
\psSolid[
   action=draw*,
   fcol=0 (OliveGreen) 2 (color1) 3 (color2),
   h=5,r=2,
   object=cylindre,
   ngrid=2 12,
   RotY=-20
](0,0,-2.5)
\end{pspicture}
\end{LTXexample}



\subsection{Torus}

\begin{LTXexample}[width=6cm]
\begin{pspicture}(-3,-2)(3,2)
\psset{viewpoint=50 50 30 rtp2xyz,Decran=25,lightsrc=viewpoint}
\psSolid[r1=2.5,r0=1.5,
    object=tore,
    ngrid=4 36,
    fillcolor=green!30,
    action=draw**]%
\axesIIID(4,4,0)(5,5,4)
\end{pspicture}
\end{LTXexample}

\begin{LTXexample}[width=6cm]
\begin{pspicture}(-3,-2)(3,2)
\psset{viewpoint=50 50 30 rtp2xyz,Decran=25,lightsrc=viewpoint}
\psSolid[r1=3.5,r0=1,
    object=tore,
    ngrid=9 18,
    fillcolor=magenta!30,
    action=draw**]%
\axesIIID(4.5,4.5,0)(5,5,4)
\end{pspicture}
\end{LTXexample}

\endinput