3

Is there any slick way to create an n-sided (n is some arbitrary integer, e.g. n = 23) regular polygon, inscribed into a circle, using tkz-euclide?

Or do I have to use the plain TikZ functions (not as intuitive as tkz-euclide)?

Svend Tveskæg
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marmistrz
  • 489
  • 3
  • 14

3 Answers3

8

I find your lack of faith disturbing...

\documentclass[tikz]{standalone}
\usetikzlibrary{shapes.geometric,calc}
\begin{document}
\begin{tikzpicture}
\node[regular polygon,regular polygon sides=23,draw,minimum height=5cm] (a) at (0,0) {};
\draw[red] let \p1=($(a.corner 1)-(a.center)$), \n1={veclen(\x1,\y1)} in circle (\n1);
\foreach \x[count=\xi] in {A,B,...,W}{
  \node (a-\xi) at ([shift={({90+(\xi-1)*360/23}:3mm)}]a.corner \xi) {\x};
}
\end{tikzpicture}
\end{document}

enter image description here

Roland
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percusse
  • 157,807
  • And if I'd like to label the vertices A,B,C,...? What should be added then? – marmistrz Mar 08 '15 at 17:28
  • @marmistrz Added. – percusse Mar 08 '15 at 17:34
  • Thanks! Could you please explain how the lines 6-8 work? – marmistrz Mar 08 '15 at 17:46
  • Nice (+1)! I had no idea the ... syntax could handle alphabetic sequences automatically. – Paul Gessler Mar 08 '15 at 18:16
  • @marmistrz It goes through every corner anchor which TikZ automatically numbers starting from the top. Then it places a node at each of those but instead placing them right on the anchor it shifts them the amount of 23 degrees depending on the number of iteration which is held in \xi. It's just a compact notation trust me nothing fancy happening. – percusse Mar 08 '15 at 19:02
6

A PSTricks solution using the pst-poly package:

\documentclass{article}

\usepackage{pst-poly}

% parameters
\def\radius{4}
\def\sides{12}

\begin{document}

\begin{pspicture}[dimen = m](-\radius,-\radius)(\radius,\radius)
  \rput(0,0){\PstPolygon[PolyNbSides = \sides, unit = \radius]}
  \pscircle(0,0){\radius}
\end{pspicture}

\end{document}

output

Svend Tveskæg
  • 31,033
3

A MetaPost solution using a macro of my own. Example shamelessly inspired from Svend Tveskæg's answer.

\documentclass[border=2bp]{standalone}
\usepackage{luamplib}
\begin{document}
\begin{mplibcode}
vardef regular_polygon(expr center, radius, n) =
    save angl; angl := 360/n;
    (right for i = 1 upto n-1: -- dir(i*angl) endfor -- cycle) 
        scaled radius shifted center
enddef;
beginfig(0);
    draw regular_polygon(origin, 4cm, 12);
    draw fullcircle scaled 8cm;
endfig;
\end{mplibcode}
\end{document}

output

Edit Another version, a bit more elaborated, with alphabetic labels. The number of summits n must be lower than 27 to keep the labeling coherent :-)

\documentclass[border=2bp]{standalone}
\usepackage{luamplib}
    \mplibsetformat{metafun}
    \mplibtextextlabel{enable}
\begin{document}
\begin{mplibcode}
vardef regular_polygon(expr centre, radius, n) =
    clearxy; save angl; angl := 360/n; 
    z0 = centre + radius*right; freelabel("$A$", z0, centre); 
    z0 for i = 1 upto n-1:
        hide(z[i] = z[i-1] rotatedaround(centre, angl); 
            freelabel("$" & char(65+i) & "$", z[i], centre)) 
        -- z[i] 
    endfor -- cycle
enddef;
beginfig(0);
    draw regular_polygon(origin, 4cm, 12) withcolor red;
    draw fullcircle scaled 8cm;
endfig;
\end{mplibcode}
\end{document}

enter image description here

Franck Pastor
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