How to make bend lines/arrows with TikZ?

Question

I've been testing out TikZ lately, but I'm still quite new to it. What I want to do is to create a line to indicate that a parameter belongs to a part of the drawing. For example "This surface that I'm pointing at has temperature T". What I've seen used sometimes is to have a line or arrow with a small S-bend on the middle. I think this is a good idea as it's easy to see that the line doesn't have anything to do with the body you're drawing. Unfortunatley I had some problems finding a picutre explaining what I'm thinking of. The arrow specifying P_θ on this picture was the best I could find allthough it's not completly the same.

Is there any easy way to do something like this in TikZ? I have no idea what it would be called...

Answer 1

There are a number of ways you can do this in TikZ. Here are three examples:

\begin{tikzpicture}
  \node[anchor=east] at (0,0) (text) {This is some text.};
  \node[anchor=west] at (3,1) (description) {Here is the description.};
  \draw (description) edge[out=180,in=0,->] (text);
\end{tikzpicture}

\begin{tikzpicture}
  \node[anchor=east] at (0,0) (text) {This is some text.};
  \node[anchor=west] at (3,1) (description) {Here is the description.};
  \draw[->] (description) -| (text);
\end{tikzpicture}

\begin{tikzpicture}
  \node[anchor=east] at (0,0) (text) {This is some text.};
  \node[anchor=west] at (3,1) (description) {Here is the description.};
  \draw[->] (description) .. controls ([xshift=-4cm] description) and ([xshift=4cm] text) .. (text);
\end{tikzpicture}

which produces