If you name the node in the second slide you can use a fill=<color> with fill opacity=<num>. By naming the node we can easily access the coordinates of the vertices so that we can traverse the region we want to fill:
\draw[red,ultra thick] (0,0) rectangle (0.5,0.5);
\fill [draw=none, fill=white, fill opacity=0.3]
(0,0.5) --
(A.north west) -- (A.north east) -- (A.south east) --
(0.5,0) -- (0.5,0.5) -- cycle;
Using a modified version showing those two images side by side to see the effect:
Notes:
- To get the images to align I shifted the drawing of the box by
0.5\pgflinewidth. So if you notice that your beamer image shifts from slide to slide, you will need to apply this shift as well.
- Even with this adjustment, the second image appears to be off slightly and I don't know why. So perhaps another tweak is required.
Code:
\RequirePackage[demo]{graphicx}
\documentclass{beamer}
\usetheme{Copenhagen}
\usecolortheme{whale}
\useinnertheme{rounded}
\usepackage{tikz}
\newcounter{boxes}
\newcommand\ordbox[2]{%
\stepcounter{boxes}
\tikz[remember picture,overlay]{
\node[rectangle,rounded corners,line width=2pt,draw=red,fill=pink,text height=10pt,text depth=3pt,align=left,draw opacity = 0.75, fill opacity=.75,text opacity=1] (box-\theboxes) at #2 {#1};}
}
\newcommand\tikzmark[1]{%
\tikz[remember picture,overlay] \node (#1) {};}
\begin{document}
\begin{frame}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] at (0,0) {\includegraphics[scale=0.2]{../images/H1D_level_5.pdf}};
\end{tikzpicture}
\end{frame}
\begin{frame}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] (A) at (0,0) {\includegraphics[scale=0.2]{../images/H1D_level_5.pdf}};
\draw[red,ultra thick] (0,0) rectangle (0.5,0.5);
\fill [draw=none, fill=white, fill opacity=0.3] (0,0.5) -- (A.north west) -- (A.north east) -- (A.south east) -- (0.5,0) -- (0.5,0.5) -- cycle;
\end{tikzpicture}
\end{frame}
\end{document}
Code:
Modified to generate the image above.
\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\newcommand\tikzmark[1]{\tikz[remember picture,overlay] \node (#1) {};}
\newcommand*{\Size}{2.5}%
\begin{document}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] at (0,0) {\includegraphics[scale=0.1]{./images/EiffelWide.jpg}};
\end{tikzpicture}
%
\begin{tikzpicture}
\node[anchor=south west,inner sep=0] (A) at (0,0) {\includegraphics[scale=0.1]{./images/EiffelWide.jpg}};
\draw[red,ultra thick] (0.5\pgflinewidth,0.5\pgflinewidth) rectangle (\Size,\Size);
\fill [draw=none, fill=white, fill opacity=0.4]
(\pgflinewidth,\Size) --
(A.north west) -- (A.north east) -- (A.south east) --
(\Size,\pgflinewidth) -- (\Size,\Size) -- cycle;
\end{tikzpicture}
\end{document}
Best Answer
(This answer was migrated from the original question)
If I understood correctly the question, the following code may help to devise an appropiate solution:
Macro
\rowofmen{x}produces a row of x men, allowing for fractional values of x (the trick is to draw one more man and clipping the resulting figure). Superimposing several of these rows with different colors and lenghts (as in the\rlapexample), you can simulate half-shaded men. This is the output:Note that each man was resized to 2mm x 3mm. You can alter this by changing the parameters
x=2mm,y=3mmof thetikzpictureand those of\resizebox. The remaining can be left unchanged.