# [Tex/LaTex] How to draw irregular shading area with tikz

tikz-pgf

How can I draw with tikz the irregular shaded area and (similarly?) the irregular frame around nodes like the ones in the image?

A simple and quick example for Carol

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix,shapes.geometric,calc,backgrounds}
\begin{document}
\begin{tikzpicture}
\matrix (gamea) [matrix of nodes,nodes={circle,draw},row sep=5mm,column sep=5mm]{
& 1 &\\
2& |[draw=none]|3 & 4\\
|[draw=none]| 5 & 6 & |[draw=none]|7\\
& |[draw=none]|8 &\\
};
\draw ($(gamea-3-1)!0.5!(gamea-4-2)$) ellipse [x radius=1.2cm, y radius=0.30cm,rotate=-45];
\draw ($(gamea-2-2)!0.5!(gamea-3-3)$) ellipse [x radius=1.2cm, y radius=0.30cm,rotate=-45];
\begin{scope}[on background layer]
\fill[black!20,rounded corners] ([xshift=-2mm]gamea-2-3.west) arc (180:0:5mm and 5mm) --
([xshift=1mm]gamea-3-3.east) arc (0:-90:1cm and 1.5cm) arc
(-90:-180:1cm and 0.8cm) |- ([shift={(3mm,2mm)}]gamea-3-2.north east) -- cycle;
\end{scope}
\end{tikzpicture}
\end{document}