Some Tikz and tikz-er2 doodles for Latex

tikz_doodle.tex

\documentclass[12pt, letterpaper]{article}
\usepackage{fontspec}
\usepackage{tikz-er2}
\usetikzlibrary{positioning}

\begin{document}
\begin{figure}[h!]
  \begin{center}
    \begin{tikzpicture}[node distance=2cm]
		\node[entity] (emp) {Employee};
		\node[attribute] (ename) [above=0.2cm of emp] {Name} edge (emp);
		\node[attribute] (enum) [left=1cm of emp] {\key{Number}} edge (emp);
		\node[isa] (isa) [below of=emp] {\discriminator{ISA}} edge (emp);
		\node[total] (tot) [below right=0.7cm and 1cm of emp] {TOTAL} edge (emp);
		\node[entity] (car) [right=4cm of emp] {Car};
		\draw[help lines, dashed,color=gray] (0.1,0.1) grid(3.9,3.9);
		\draw [thick, dotted,color=blue] (0,2) to (2,4);
		\draw[->,>=diamond,thick,color=red] (2,4) -- (4,2) |- (2,0);
    \end{tikzpicture}
    \caption{Example graphic made with tikz.}
  \end{center}
\end{figure}

\begin{figure}[htpb]
	\centering
	\begin{tikzpicture}[scale=2.5]
		\tikzstyle{every node}=[draw,shape=circle];
		\path (0,0) node (v0) {$v_0$};
		\path (1,1) node (v1) {$v_1$};
		\path (2,0) node (v2) {$v_2$};
		\draw (v0) -- (v1) -- (v2) -- (v0);
	\end{tikzpicture}
	\caption{Another tikz tree struction}
	\label{fig:tikzTree}
\end{figure}

\end{document}