%%
%% The LaTeX Companion, 3ed
%%
%% Example 8-3-9 on page I-607 in "New commands".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{111.0pt}

%StartShownPreambleCommands
\usepackage{xcolor,pict2e}
\newcommand\octet{\begin{picture}(0,0)(15,15)
   \polygon(0,10)(0,20)(10,30)(20,30)(30,20)(30,10)(20,0)(10,0)
  \end{picture}}
%StopShownPreambleCommands

\begin{document}
\begin{picture}(80,60)
  \polyvector(20,60)(40,40)(60,20) \Vector(40,40)(20,20)
  \put(20,20){\octet} \put(40,40){\octet} \put(60,20){\octet}
 \color{blue}         \polygon*(35,15)(45,15)(45,25)(35,25)
  \Vector(40,40)(40,25)
\end{picture}
\end{document}