[pstricks] Defining a command

[Herbert Voss]

Konrad Viltersten wrote:
> I've defined the following command.
>
> \newcommand{\something}[4]
> {\pspolygon (#1,#2) (#3,#2) (#3,#4) (#1,#4)}
>
> As i've been rectangling a lot, it was extremely useful.
> Now, i'll be rombing for a while but i seem to get stuck
> on how to define it so i only need to specify two points
> when calling it...
>
> It will be something like this.
>
> \newcommand{\something}[4]
> {\pspolygon
>     (#1,#2)
>     (#3,#4)
>     (2 * #3 - #1,#2)
>     (#3,2 * #2 - #4)}
>
> Now, the problem is that i still don't really get how to
> perform multiplication and subtraction inside there.
> Suggestions?
>   
\listfiles
\documentclass{article}
\usepackage{pstricks}
\SpecialCoor

\newcommand{\something}[4]{%
  \pspolygon(#1,#2)(#3,#4)(! #3 dup add #1 sub #2)(! #3 #2 dup add #4 sub)}

% better, can have optional arguments
\makeatletter
\def\psPolygon{\@ifnextchar[\psPolygon at i{\psPolygon at i[]}}
\def\psPolygon at i[#1](#2,#3)(#4,#5){%
  \pspolygon[#1](#2,#3)(#4,#5)(! #4 dup add #2 sub #3)(! #4 #3 dup add
#5 sub)}
\makeatother

\begin{document}

\something 1 2 3 4 \hspace{2cm}
\psPolygon[linecolor=red,fillstyle=solid](1,2)(3,4)

\end{document}


Herbert


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