Creating two filled plots that overlap with transparency

Question

I'm using pgfplots to plot two filled curves. I'd like them to overlap transparently so that the "lower" figure can be seen through the "upper one". Using the forget style mode will draw the first figure transparently, but that's the one that is below !

MWE:

\begin{tikzpicture}
  \begin{axis}[ybar,bar width=2pt]
  \addplot[color=red,mark=,draw=red,fill opacity=0.5] table[x=0,y=1]\transtable;
  \addplot[color=blue,mark=,draw=blue,fill opacity=0.5] table[x=2,y=3]\transtable;
  \end{axis}
\end{tikzpicture}

Is there a direct way to get somewhat transparent overlapping plots ?

Answer 1

You can use fill opacity key to change the ...hmm... fill opacity.

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\begin{document}
\begin{tikzpicture}
  \begin{axis}[enlargelimits=false]
  \addplot[red,no marks,fill] {x} \closedcycle;
  \addplot[no marks,fill,blue,fill opacity=0.2,samples=100] {10*sin(x*20*pi)} \closedcycle;
  \end{axis}
\end{tikzpicture}
\end{document}