Q: Shaded half-ellipsoids in TikZ I can simulate a set of balls (blue). I can also simulate a set of ellipsoids (yellow}.
How to obtain a set of half-ellipsoids?
\documentclass{article}
\usepackage{xcolor}
\usepackage{tikz,pgffor}

\usetikzlibrary{shadows}
\usetikzlibrary{shapes.geometric}
\begin{document}


\begin{tikzpicture}

\foreach \x  in {1,2,3,4}
        \shadedraw [ball color=blue] (\x,2.5,13) 
        circle (0.45cm);
\end{tikzpicture}


\begin{tikzpicture}[yscale=2]

\foreach \x  in {1,2,3,4}
        \shadedraw [ball color=yellow] (\x,2.5,13) 
        circle (0.45cm);
\end{tikzpicture}

\end{document}



A: You don't need to scale anything, but shading an appropriate shape, like this:

\documentclass{article}

\usepackage{xcolor}
\usepackage{tikz,pgffor}

\usetikzlibrary{shadows}
\usetikzlibrary{shapes.geometric}
\begin{document}


\begin{tikzpicture}

\foreach \x  in {1,2,3,4}
        \shadedraw [ball color=blue] (\x,2.5,13) 
        circle (0.45cm);
\end{tikzpicture}


\begin{tikzpicture}

\foreach \x  in {1,2,3,4} 
    \shadedraw [ball color=yellow] (-0.45+\x,2.5,13) arc(-180:0:0.45 and 0.225) arc(0:180:0.45 and 0.9) -- cycle;
\end{tikzpicture}

\end{document}

