[Tex/LaTex] How to rotate a tikz rectangle about a specific axis

beamerrotatingtikz-pgf

I am trying to create a beamer animation using tikz, but I can't even get basic rotating of a tikz image working as desired.

I have a rectangle specified by

\draw[rounded corners,dotted] (-3.5,0) rectangle (-0.5,2);

I would like to rotate this rectangle about the point (-1,.5) (which is near the bottom right corner of the rectangle). I've tried:

{\rotatebox[origin=c,x=-1,y=.5]{130}{
            \draw[rounded corners,dotted] (-3.5,0) rectangle (-0.5,2);}}

But this produces an error. If I just use the origin=c option, it compiles, but it rotates the rectangle about the point (0,0). I've also tried it with just the x=-1,y=.5 (without the origin option), and it fails to compile.

I have searched the documentation, which is where I learned about the options x=xdim and y=ydim. However, I can't find a single example demonstrating how these options should be used.

Any suggestions would be greatly appreciated.

Also, if there is a better command for rotating things that will be more suitable for use in a beamer animation, please let me know. Thanks!

Best Answer

TikZ has a rotate around={<angle>:<coordinate>} option:

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\fill (-1,0.5) circle [radius=2pt];
\draw[rounded corners] (-3.5,0) rectangle (-0.5,2);
\draw[rounded corners,red,rotate around={30:(-1,0.5)}] (-3.5,0) rectangle (-0.5,2);
\end{tikzpicture}
%
\end{document}

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Other than using the \foreach command or defining a new command, you may repeat pictures by at least two other ways. (solution to the grid problem is found at the end of my answer)

1- (not tikz specific) : use the \newsavebox, \savebox and \usebox commands. The advantage of savebox is that the picture is not redrawn everytime it is called. For example:

\documentclass{minimal}

\usepackage{tikz}

\begin{document}

\newsavebox{\test}
\savebox{\test}{\tikz \draw[red] (0,0) circle (1cm);}

\begin{tikzpicture}
\draw (0,0) node {\usebox{\test}};
\draw (7,0) node {\usebox{\test}};
\end{tikzpicture}


\end{document}

2- (tikz specific) Use the object-oriented capabilities of tikz and pgf. The details are found in the tikz manual. For example, the code found on page 554 of the manual:

\documentclass{minimal}

\usepackage{tikz}
\usepgfmodule{oo}

\begin{document}

\pgfooclass{stamp}{ % This is the class stamp
    \method stamp() { % The constructor 
    }
    \method apply(#1,#2) { % Causes the stamp to be shown at coordinate (#1,#2)
        %Draw the stamp:
        \node [rotate=20] at (#1,#2) {Passed};
    }
}
\pgfoonew \mystamp=new stamp()
\begin{tikzpicture}
        \mystamp.apply(1,2)
        \mystamp.apply(3,4)
\end{tikzpicture}

\end{document}

About the grid problem. I don't have a good explanation about why the problem is occurring other than the shift in coordinates isn't being treated by tikz the way you expect them to (not much of an explanation I admit). A good way to solve the problem is to use the scope environment, and shift the whole environment, as described by the following code (I somewhat simplified your loop to make the scope environment stand out):

\begin{tikzpicture}[scale=1,thick]
  \foreach \xoffset in {0,5.2}
  {
    \begin{scope}[shift={(\xoffset,0)}]
        \draw[xstep=1,ystep=1] (0,0) grid (5,5);
    \end{scope}
  }
\end{tikzpicture}

The scope environment acts as box that may be moved around (shifted or rotated) as a whole. If you are familiar with pstricks, it is similar to the \rput command.

[Tex/LaTex] Drawing a triangle with rounded corners in TikZ

Make the radius of the rounded corners smaller. Remove =10mm and you will see the instant effect. Also, in your case, I find no need to load the xcolor package since it is used internally by tikz, unless, as noted by Alain Matthes, you use some of its options for naming your colors. You can uncomment it if you like. The libraries are not needed here, too, so I commented them out.

Here is your figure when the 10mm is dropped.

enter image description here

And here is one with scaling (not really necessary, just for demonstration purposes).

%\documentclass{article}

\documentclass[border=5]{standalone}

\usepackage{tikz}
%\usepackage{xcolor}
%\usetikzlibrary{arrows,shapes,snakes,automata,backgrounds,petri}

\begin{document}
\begin{tikzpicture}[scale=3]
    \draw [rounded corners,fill=gray!20] (0,0)--(1,0)--(0.5,1)--cycle;
\end{tikzpicture}
\end{document}

enter image description here

Here I have scaled the figure up to 3 since your figure is too small.

To make a point, see what happens when I scale the figure up by 5 and set rounded corners=10mm.

enter image description here

Best Answer

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