Re: pgfmathparse can disrupt coordinate transformations?

> Hello,
>
> I was playing a bit with the Lindenmayer libary of PGF-CVS, and I
> wanted to use it to create a Penrose P3 Tiling  [1] (ideally,
> something like this: http://berteun.nl/tmp/penrose.pdf); for which
> Wikipedia has an L-system. But, to make things fancier, I decided not
> to wait until the whole path was constructed, but to stroke and fill
> as soon as a ] was hit. In order to decide what to do, I used some
> calculations, but \pgfmathparse appears to be able to disrupt the
> coordinate transformations, because a single usage of it can make the
> tiles appear quite misplaced.
>
> The above hopefully explains why I would stroke the path in between.
> The culprit appears to be         \pgfmathparse{and(0>0,0<1)}, if I
> remove the line, the picture comes out alright. Also, if I replace 0>0
> by something which is true, like 1>0, the picture comes out alright.
> The problem only occurs if the left hand side of the and is false (the
> right hand side does not matter). This was as far as I was able to pin
> down the problem. I tried to create a smaller example without a
> Lindenmayer system, but I didn't succeed.
>
> I also tried the latest CVS build on Kjells site (31-10-2008), which
> still has the problem. I can work around it (and did to produce the
> picture in the PDF), but it appears to be a bug to me.
>
> Berteun
>
> [1] http://en.wikipedia.org/wiki/Penrose_tiling
>
> %%%
> \documentclass{article}
> \usepackage{tikz}
> \usetikzlibrary{lindenmayersystems}
> \begin{document}
> \pgfdeclarelindenmayersystem{Penrose Tiling}{
>    \symbol{]}{
>        %Comment the next line, or replace 0>0 by 1>0 and the result is fine.
>        \pgfmathparse{and(0>0,0<1)}
>        \pgfusepath{stroke}
>        \pgflsystemrestorestate
>    }
>    \rule{A -> [7]++[7]++[7]++[7]++[7]}
>    \rule{6 -> 8F++9F----7F[-8F----6F]++}
>    \rule{7 -> +8F--9F[---6F--7F]+}
>    \rule{8 -> -6F++7F[+++8F++9F]-}
>    \rule{9 -> --8F++++6F[+9F++++7F]--7F}
>    \rule{F -> }
> }
>
> \begin{tikzpicture}
>    \path[use as bounding box] (-5,5) rectangle (5, 5);
>    \path[rotate=-18,lindenmayer system={Penrose Tiling, axiom=A,
>        order=2, angle=36, step=1cm}] lindenmayer system;
> \end{tikzpicture}
>
> \end{document}
> %%%%
>
> -------------------------------------------------------------------------
> This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
> Build the coolest Linux based applications with Moblin SDK & win great prizes
> Grand prize is a trip for two to an Open Source event anywhere in the world
> http://moblin-contest.org/redirect.php?banner_id=100&url=/
> _______________________________________________
> pgf-users mailing list
> pgf-users@...
> https://lists.sourceforge.net/lists/listinfo/pgf-users
>