2

I'm trying to draw a diagram with slanted grids in it, sort of like the 3D effect given at http://www.texample.net/tikz/examples/3d-graph-model/

Ideally, I'd like a macro slantedgrid so that for example

\draw (10,12) \slantedgrid (7,5);

or maybe even simply

\slantedgrid{10}{12}{7}{5}

will draw a grid with all vertical lines slanted at 45 degrees, the lower left corner at (10,12) and with 5+1 horizontal lines and 7+1 vertical (slanted) lines.

My first (and so far only) attempt was to define it with LaTeX "newcommand" as

\newcommand{\slantedgrid}[4]{%
  \foreach \x in {#1,#1+1,...,#1+#3} \draw (\x,#2) -- ++(#4,#4);%
  \foreach \y in {#2,#2+1,...,#2+#4} \draw (\y-#4,\y) -- ++(#3,0);%
 }

However, all this produces is loads of errors - "Illegal unit of measure (pt inserted)" - when I bung slantedgrid{10}{12}{7}{5} into a tikzpicture environment.

Is there any simple method of doing something like this - in particular passing the parameters from a newcommand to TikZ's foreach?

  • 1
    Is \foreach an essential requirement? As it stands, \draw [shift={(10,12)}, xslant=tan 45] grid ++(7,5); seems to do it nicely. – Mark Wibrow May 3 '14 at 13:07
  • Gak, arrgh! xslant makes my task almost trivial. Thank you very much! – Alasdair May 3 '14 at 13:44
2

If you want still to pass a calculated parameters to foreach you can use pgfmathtruncatemacro:

\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\newcommand{\slantedgrid}[4]{%
   \pgfmathtruncatemacro{\result}{#1+#3}
   \foreach \x in {#1,...,\result} \draw (\x,#2) -- ++(#4,#4);%
   \pgfmathtruncatemacro{\result}{#2+#4}
   \foreach \y in {#2,...,\result} \draw (#1+\y-#2,\y) -- ++(#3,0);%
 }
\slantedgrid{10}{12}{7}{5}
\end{tikzpicture}
\end{document}

enter image description here

PS: I changed second foreach to what I think you had in mind.

  • Thanks again! Yes, I was sure my second foreach was incorrect even as I posted it... – Alasdair May 3 '14 at 14:48

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