# Curved waved lines with TikZ

I'm trying to write a code for Feynman diagrams with TikZ (I know it is a common subject in the forum). I found very useful posts. However, I would like to draw a curved waved line

\documentclass{beamer}

\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,decorations.markings,snakes}

\begin{document}

\begin{tikzpicture}[thick]
\path [draw=blue]
(-4,0) -- (-2,0) -- (2,0) -- (4,0);
\draw[draw=blue,snake=coil, segment aspect=0] (2,0) arc (0:180:2cm);
\end{tikzpicture}

\end{document}


The above code just draw a solid line, no waved.

Can anyone help me solve this weird behaviour?

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You aren't invoking the decorations. A decoration needs to be defined (usually via the decoration key) and invoked, via the decorate key. –  Loop Space Jan 2 '13 at 14:56

## 1 Answer

Actually the library snakes has been superseded by decorations, but for your need I think you are just looking for decorations.pathmorphing.

Thus, your code revised, is like:

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}

\tikzset{snake it/.style={decorate, decoration=snake}}

\begin{document}
\vspace*{2cm}
\begin{center}
\begin{tikzpicture}[thick]
\path [draw=blue,snake it]
(-4,0) -- (-2,0) -- (2,0) -- (4,0);
\draw[draw=blue, snake it] (2,0) arc (0:180:2cm);
\end{tikzpicture}
\end{center}
\end{document}


Notice that I grouped in a single style snake it the keys that really set up the decoration decorate and the one that sets the type of decoration decoration=snake.

For further details, you can have a look to section 72 Decorations and more specifically to section 30.2 Path Morphing Decorations on the pgfmanual. (section 48.2 in pgfmanual 3.0)

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Thank you @claudio, your answer was very helpful!! Cheers –  Dox Jan 2 '13 at 15:26