4

i have a picture with three circles, see the minimal working example below:

\documentclass{beamer}
\setbeamercovered{transparent}
\usepackage{tikz} 

\begin{document}

\begin{frame}
\begin{tikzpicture}
\draw (1,0) circle (1);
\pause
\draw (5,0) circle (1);
\draw (10,0) circle (1);
\end{tikzpicture}
\end{frame}

\end{document}

For certain reasons, i would like to show only the first circle with a continous lins, the other circles should be visible in a semitransparent way. By using the "\pause"-command, i get an image exactly in the way i would like to have it on the first slide, but i do not want the second slide to be generated (because here all three circles are fully visible again).

Is there an option / certain command in order to "highlight" just a certain part of a whole picture? In other words, is there an option for fading out certain areas of an image?

Thanks in advance and best regards!

Claudio Fiandrino
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pythag0ra5
  • 85
  • 1
  • 5
  • Take a look into this approach: http://tex.stackexchange.com/a/55849/3751 – Daniel Feb 05 '14 at 13:14
  • I don't understand "By using the "\pause"-command, i get an image exactly in the way i would like to have it on the first slide, but i do not want the second slide to be generated (because here all three circles are fully visible again)." So, you want to display on the first slide one circle and on the second one all the circles, where two of them are transparent? – Claudio Fiandrino Feb 05 '14 at 13:19
  • I just want to have 1 slide, where the first circle should be totally visible and all others should be semitransparent – pythag0ra5 Feb 05 '14 at 13:28
  • @pythag0ra5: Hence, no need of overlays. – Claudio Fiandrino Feb 05 '14 at 13:31

3 Answers3

5

If I understand you correctly you could just put the two last circles in a scope and set opacity=0.3 (adjust the value to whatever you like).

enter image description here

\documentclass{beamer}
\setbeamercovered{transparent}
\usepackage{tikz} 

\begin{document}
\begin{frame}
\begin{tikzpicture}
\draw (1,0) circle (1);
\begin{scope}[opacity=0.3] % sets opacity to 30% for everything in the scope
\draw (5,0) circle (1);
\draw (10,0) circle (1);
\end{scope}
\end{tikzpicture}
\end{frame}
Torbjørn T.
  • 206,688
  • In case overlays would have been needed to display transparent circles on slide 2, I suggest the use of aobs-tikz. Just need to change options to the scope environment: \begin{scope}[background aspect={opacity=0.4},aspect on=<2>]. – Claudio Fiandrino Feb 05 '14 at 13:45
2

Here is one over kill with fadings library:

\documentclass{beamer}
\setbeamercovered{transparent}
\usepackage{tikz}
\usetikzlibrary{fadings}
\tikzfading[name=fade left,
            left color=transparent!10,
            right color=transparent!10]

\begin{document}
\begin{frame}
\begin{tikzpicture}
\draw (1,0) circle (1);
\draw (5,0) circle (1);
\draw (10,0) circle (1);
\fill[white,path fading=fade left] (3.9,-1.1) rectangle (11.1,1.1);
\end{tikzpicture}
\end{frame}
\end{document}

enter image description here

Here we can have a gradual fading by adjusting:

\tikzfading[name=fade left,
            left color=transparent!60,
            right color=transparent!10]

say. This gives:

\documentclass{beamer}
\setbeamercovered{transparent}
\usepackage{tikz}
\usetikzlibrary{fadings}
\tikzfading[name=fade left,
            left color=transparent!60,
            right color=transparent!10]

\begin{document}
\begin{frame}
\begin{tikzpicture}
\draw (1,0) circle (1);
\draw (5,0) circle (1);
\draw (10,0) circle (1);
\fill[white,path fading=fade left] (3.9,-1.1) rectangle (11.1,1.1);
\end{tikzpicture}
\end{frame}
\end{document}

enter image description here

1

Found on p.234 of TikZ/PGF manual: transparency. There are several ways to implement this. A simple one follows.

\begin{document}

\begin{frame}
\begin{tikzpicture}
\draw (1,0) circle (1);
\pause
\draw [draw opacity=0.3](5,0) circle (1);
\draw [draw opacity=0.3](10,0) circle (1);
\end{tikzpicture}
\end{frame}

\end{document}

If the drawing becomes more complicated, perhaps it would be better to put the opacity into a style?

olga.saucedo
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