How to draw a irregular circle(shape)?

Question

I want to draw some irregular circle(shape) in my wireless scenario.

with a basestation in the center.

around is some irregular circle(shape).

I find something(could be used) in this web(but I feel it's size is too large)

---

Now my teacher want me use this circle as small as possible, but I find when I turn the radius smaller, the irregularcicle's round isn't clear so much. Is there any idea to solve this problem?

Answer 1

Using the rand function, you can write the \irregularcircle macro:

\documentclass[tikz]{standalone}

\newcommand\irregularcircle[2]{% radius, irregularity
  \pgfextra {\pgfmathsetmacro\len{(#1)+rand*(#2)}}
  +(0:\len pt)
  \foreach \a in {10,20,...,350}{
    \pgfextra {\pgfmathsetmacro\len{(#1)+rand*(#2)}}
    -- +(\a:\len pt)
  } -- cycle
}

\begin{document}
\begin{tikzpicture}
  \coordinate (c) at (0,0);
  \coordinate (d) at (1,2);
  \draw[blue,rounded corners=1mm] (c) \irregularcircle{1cm}{1mm};
  \draw[red,rounded corners=1mm] (d) \irregularcircle{1cm}{1mm};
\end{tikzpicture}
\end{document}

Edit: a variant using let operations (from the calc library):

\documentclass[tikz]{standalone}
\usetikzlibrary{calc}
\newcommand\irregularcircle[2]{% radius, irregularity
  let \n1 = {(#1)+rand*(#2)} in
  +(0:\n1)
  \foreach \a in {10,20,...,350}{
    let \n1 = {(#1)+rand*(#2)} in
    -- +(\a:\n1)
  } -- cycle
}

\begin{document}
\begin{tikzpicture}
  \coordinate (c) at (0,0);
  \coordinate (d) at (1,2);
  \draw[blue,rounded corners=.5mm] (c) \irregularcircle{1cm}{1mm};
  \draw[red,rounded corners=.5mm] (d) \irregularcircle{1cm}{1mm};
\end{tikzpicture}
\end{document}

Answer 2

You can use plot:

  \documentclass{scrbook}
  \usepackage{tikz}
  \begin{document}
        \begin{tikzpicture}
            \draw  plot[smooth, tension=.7] coordinates {(-3.5,0.5) (-3,2.5) (-1,3.5) (1.5,3) (4,3.5) (5,2.5) (5,0.5) (2.5,-2) (0,-0.5) (-3,-2) (-3.5,0.5)};
        \end{tikzpicture}

    \begin{tikzpicture}
        \draw  plot[smooth, tension=.8] coordinates {(-2.5,-0.5) (-3.5,0) (-2.5,0.5) (-3,1) (-2,1.5) (-2,3) (-1,2.5) (1,4.5) (2.5,3) (3,3.5) (3.5,3) (3,2) (4.5,2) (4.5,0) (3,1) (2.5,-0.5) (3.5,-1.5) (1.5,-1) (0.5,-2) (-2,-2.5) (-1.5,-1) (-2.5,-1.5) (-2.5,-0.5)};
    \end{tikzpicture}
  \end{document}

Using the same points as above the curve can be drawn using the excellent hobby package:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{hobby}
\begin{document}
    \begin{tikzpicture}[use Hobby shortcut,closed=true]
        \draw (-3.5,0.5) .. (-3,2.5) .. (-1,3.5).. (1.5,3).. (4,3.5).. (5,2.5).. (5,0.5) ..(2.5,-2).. (0,-0.5).. (-3,-2).. (-3.5,0.5);
    \end{tikzpicture}

    \begin{tikzpicture}[use Hobby shortcut,closed=true]
        \draw (-2.5,-0.5).. (-3.5,0).. (-2.5,0.5).. (-3,1).. (-2,1.5).. (-2,3).. (-1,2.5).. (1,4.5).. (2.5,3).. (3,3.5).. (3.5,3).. (3,2).. (4.5,2).. (4.5,0).. (3,1).. (2.5,-0.5).. (3.5,-1.5).. (1.5,-1).. (0.5,-2).. (-2,-2.5).. (-1.5,-1).. (-2.5,-1.5).. (-2.5,-0.5);
    \end{tikzpicture}
\end{document}

Choose points as you wish and leave the rest to hobby. For more details, use texdoc hobby or texdoc.net.

Answer 3

Paul Gaborit's answer is a bit outdated. Now the rand function is rnd and there's the decorations library which can be used to make irregular circles with sharp irregularities.

For smooth irregularities the plot path specifier (used by user11232) can be used along with the rnd function too, removing the necessity to create coordinates. The below MWE presents both solutions.

MWE

\documentclass[margin=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}
\begin{document}
  \begin{tikzpicture}
    \draw plot[domain=0:350, smooth cycle] (\x:2+rnd*0.5);
\draw[decoration={random steps, amplitude=2mm}, decorate] (4.5,0) circle (2);

\end{tikzpicture}
\end{document}

Answer 4

With PSTricks (just for typing exercise).

Single

• Verbose:

  \documentclass[pstricks,border=12pt]{standalone}
  \usepackage{pst-node,pst-plot}
  \pstVerb{realtime srand}
  \psset{plotpoints=50}
  \def\points{}
  
  \begin{document}
  \begin{pspicture}(-2,-2)(2,2)
      \curvepnodes{0}{360}{Rand 1.50 add t PtoC}{X}
      \multido{\i=0+1}{\Xnodecount}{\xdef\points{\points (X\i)}}
      \expandafter\psccurve\points
  \end{pspicture}
  \end{document}
  

• Compact:

  \psnccurve is a new macro (among others) in pst-node to pass an array of nodes to \psccurve without creating the concatenating macro \points (as used in the code above). Now I can save more keystrokes.

  \documentclass[pstricks,border=12pt]{standalone}
  \usepackage{pst-node,pst-plot}
  \pstVerb{realtime srand}
  \psset{plotpoints=50}
  
  \begin{document}
  \begin{pspicture}(-2,-2)(2,2)
      \curvepnodes{0}{360}{Rand 1.50 add t PtoC}{X}
      \psnccurve(0,\Xnodecount){X}
  \end{pspicture}
  \end{document}
  

Multiple

• Verbose:

  \documentclass[pstricks,border=12pt]{standalone}
  \usepackage{pst-node,pst-plot}
  \pstVerb{realtime srand}
  \psset{plotpoints=50}
  
  \begin{document}
  \psLoop{10}{%
  \begin{pspicture}(-2,-2)(2,2)
      \curvepnodes{0}{360}{Rand 1.50 add t PtoC}{X}
      \def\points{}% empty for each iteration
      \multido{\i=0+1}{\Xnodecount}{\xdef\points{\points (X\i)}}
      \expandafter\psccurve\points
  \end{pspicture}}
  \end{document}
  

• Compact:

  \documentclass[pstricks,border=12pt]{standalone}
  \usepackage{pst-node,pst-plot}
  \pstVerb{realtime srand}
  \psset{plotpoints=50}
  
  \begin{document}
  \psLoop{10}{%
  \begin{pspicture}(-2,-2)(2,2)
      \curvepnodes{0}{360}{Rand 1.50 add t PtoC}{X}
      \psnccurve(0,\Xnodecount){X}
  \end{pspicture}}
  \end{document}
  

Notes

\psnline, \psncurve, and \psnccurve are available but \psnpolygon is not.

Attention

Note that Rand no longer produces a random real number between 0 and 0.5 inclusive. Its definition had been tacitly changed. Now it produces a random real number between 0 and 1 inclusive. It is not documented, nor announced, but it is still fun!

The code given above has not been updated yet so it will produce different output. I have no time to update it right now. Sorry for this inconvenience.