# [pstricks] vanishing plane

Herbert Voss Herbert.Voss at FU-Berlin.DE
Sat Jun 9 18:56:16 CEST 2012

Am 09.06.2012 18:44, schrieb Herbert Voss:
> Am 09.06.2012 18:39, schrieb Jon Joseph:
>> Ok. I get it. But I gotta say that just seems wrong given the fact
>> that my cylindrical surface is still visible from both viewpoints even
>> though it also has a front and a back.
>
> yes, but it has a defined color for the the outside and the inside

use the object face instead, if you want both side visible.
A face object is by default in the x-y plane, but can be
rotated.

\documentclass{article}
\usepackage[svgnames]{pstricks}
\usepackage{pst-solides3d}

\begin{document}

\psset{viewpoint=30 10 30, Decran=50}
\begin{pspicture}[showgrid=false](-1.5,-3)(6.5,6)
\psSolid[object=grille,base=-3 3 -1 6,action=draw**,fillcolor=gray!20]
\defFunction[algebraic]{G5}(t){t}{0.5*t^2}{0}
\defFunction[algebraic]{G6}(t){t}{0.5*t^2}{4}
\psSolid[object=face,fillcolor=Aquamarine,incolor=red,
RotX=90, base=-3 4 -3 0 3 0 3 4]
\psSolid[object=cylindre,range=-3 2,h=4,function=G5,axe=0 0 1,
incolor=cyan!50, fillcolor=yellow!50, ngrid=3 8]
\axesIIID(0,4.5,0)(4,6,5)
\end{pspicture}
% Changed the viewpoint and the plane disappears

\psset{viewpoint=30 -10 30, Decran=50}
\begin{pspicture}[showgrid=false](-1.5,-3)(6.5,6)
\psSolid[object=grille,base=-3 3 -1 6,action=draw**, fillcolor=gray!20]
\defFunction[algebraic]{G5}(t){t}{0.5*t^2}{0}
\defFunction[algebraic]{G6}(t){t}{0.5*t^2}{4}
\psSolid[object=cylindre, range=-3 2,h=4, function=G5, axe=0 0 1,
incolor=cyan!50, fillcolor=yellow!50, ngrid=3 8]
\psSolid[object=face,fillcolor=Aquamarine,incolor=red,
RotX=90, base=-3 4 -3 0 3 0 3 4]
\axesIIID(0,4.5,0)(4,6,5)
\end{pspicture}

\end{document}

Herbert