[pstricks] Slices of a solid of revolution

[Herbert Voss]

Chicoine Martin wrote:
> I would like to draw the slices of a solid of revolution as in the following example :
>
> http://www.seg.etsmtl.ca/Math/Animations/disqRMin1.htm
>
> Does something exist that could do it?
>   

We can make it exist ... :-)

Herbert

\documentclass{article}
\usepackage{pst-plot}
\SpecialCoor
\usepackage{multido}
\parindent=0pt

\def\psVolume(#1,#2)#3#4{{
\begin{pspicture}(-1,-2.1)(5,2.1)
  \psaxes{->}(0,0)(0,-2)(5,2)
  \psplot{#1}{#2}{#4}\psplot{#1}{#2}{#4 neg}
  \multido{\iA=1+1}{#3}{%
    \pscustom[fillcolor=green,fillstyle=solid]{%
      \code{
        /dX #2 #1 sub #3 div def
        /Start dX \iA\space 1 sub mul def
        /End Start dX add def
        /Height End Start add 2 div /x ED #4 def }
      \psellipticarc(!Start 0)(!0.25 Height){90}{270}
      \rlineto(! dX 0)
      \psellipticarc(!End 0)(!0.25 Height){270}{90}
      \rlineto(!dX neg 0)}}
  \psline{->}(#2,0)(5,0)
  \psellipticarc(#2,0)(!0.25 #2 dup #1 sub #3 div 2 div sub
    TeXDict begin /x ED #4 end){90}{270}
 
\psset{plotstyle=line,linestyle=dashed,plotpoints=40,dotstyle=*,dotsize=0.5pt}
  \psplot{#1}{#2}{#4}\psplot{#1}{#2}{#4 neg}
\end{pspicture}
}}

\begin{document}

\psVolume(0,4){1}{x sqrt}\\
\psVolume(0,4){2}{x sqrt}\\
\psVolume(0,4){4}{x sqrt}\\
\psVolume(0,4){8}{x sqrt}\\
\psVolume(0,4){16}{x sqrt}\\
\psVolume(0,4){32}{x sqrt}

\end{document}