[OS X TeX] set difference using TikZ and beamer

[David Watson]

On Mar 20, 2009, at 1:11 PM, Alain Matthes wrote:

> % Animate a set intersection operation.
> % Standalone version contributed by Alexander Grahn
> \documentclass{beamer}
> \usepackage{tikz}
> \usepackage{animate}
>
> \usepackage{fp}
>
> % parameterized tikz graphics
> \newcommand{\intersect}[1]{%
>  \def\setA{(0,0) circle (1)}%
>  \def\setB{(#1,0) circle (1)}%
>  % define the bounding box
>  \def\boundb{(-2,2) rectangle (4,-2)}%
>  %
>  \begin{tikzpicture}
>    \draw \boundb;
>    % intersection
>    \begin{scope}
>      \clip \setA;
>      \fill[black!20] \setB;
>    \end{scope}
>    \begin{scope}[even odd rule]% first circle without the second
>      \clip \setB \boundb;
>      \fill[red!20] \setA;
>    \end{scope}
>    \begin{scope}[even odd rule]% first circle without the second
>      \clip \setA \boundb;
>      \fill[blue!20] \setB;
>    \end{scope}
>    \draw \setA;
>    \draw \setB;
>    \node at (-1,0) [left] {$A$};
>    \node at (#1+1,0) [right] {$B$};
>    \node at (4,2) [below left] {$A\cap B$};
>  \end{tikzpicture}
> }
>
> \begin{document}
>
> \begin{frame}
>  \frametitle{Set intersection}
>  \begin{center}
>
>    \begin{animateinline}[autoplay,palindrome]{12}
>      %first frame, xb=0.0
>      \gdef\xb{0}% xb initial value
>      \intersect{\xb}%
>      %remaining frames, xb=0.1...2.1
>      \whiledo{\lengthtest{\xb pt < 2.1pt}}{%
>    	\newframe
>    	\FPeval{xb}{\xb+0.1}% new xb
> 		\xdef\xb{\xb}% make \xb global
>    	\intersect{\xb}%
>      }%
>    \end{animateinline}
>
>  \end{center}
> \end{frame}
> \end{document}

This example is pretty cool, but only in Adobe Reader. Skim, Preview,  
and TeXShop don't show the moving intersection. I wish I had thought  
to "texdoc animate" before typesetting this and being puzzled by the  
strangely unanimated result.

I don't suppose javascript in PDF is scheduled for Snow Leopard.
But then again, I would hate to open up the underpinnings of Mac OS X  
to vulnerabilities such as the recently announced Adobe Reader  
problems... unless people were using LaTeX to infect their victims  
with a sense of mathematical wonder.