\section{Drawing a \Index{line}} This command is adapted from the macro \verb+\pstThreeDLine+ from the package \texttt{pst-3dplot} of Herbert \textsc{Voss}% \footnote{\url{http://tug.ctan.org/tex-archive/graphics/pstricks/contrib/pst-3dplot}.} We use \texttt{\textbackslash psLineIIID[options](x0,y0,z0)(x1,y1,z1)\ldots(xn,yn,zn)}, with the following possible options: \begin{itemize} \item \texttt{\Lkeyword{linecolor}=colour}; \item \texttt{\Lkeyword{doubleline}=true}; \item \texttt{\Lkeyword{linearc}=value}. \end{itemize} It is not possible to put arrowheads at the ends of the lines. \begin{LTXexample}[width=6.5cm] \psset{viewpoint=50 20 30 rtp2xyz,Decran=50} \begin{pspicture}(-3,-4)(4,4) \psSolid[object=cube,a=4,action=draw*, fillcolor=magenta!20]% \psLineIIID[linecolor=blue, linewidth=0.1,linearc=0.5, doubleline=true](-2,-2,-2)(2,2,2)(2,2,-2)(2,-2,0) \psPoint(2,-2,0){A}\psPoint(-2,-2,-2){B} \psPoint(2,2,2){C}\psPoint(2,2,-2){D} \psdot[dotsize=0.2](A)\psdot[dotsize=0.2](B) \psdot[dotsize=0.2](C)\psdot[dotsize=0.2](D) \psLineIIID[linecolor=green]% (-2,-2,-2)(2,2,2)(2,2,-2)(2,-2,0) \psPolygonIIID[linecolor=red, fillstyle=vlines,linearc=0.5, linewidth=0.1](-2,-2,2)(-2,2,2)(2,2,2)(2,-2,2) \axesIIID(2,2,2)(4,4,4) \end{pspicture} \end{LTXexample} \endinput