# Draw a Graph
Drawing is basic usage of TeX. Perhaps you know
[graphviz](
https://graphviz.org/), another drawing languages:
`main.gv`:
```dot
digraph G{
a -> b -> {c, d}
}
```
```sh
dot -Tpng -omain.png main.gv
```
You don't need to declare the position of node a, b, c and d.
The compiler of graphviz will calculate it:
```sh
dot main.gv
```
```dot
digraph G {
graph [bb="0,0,126,180"];
node [label="\N"];
{
c [height=0.5,
pos="27,18",
width=0.75];
d [height=0.5,
pos="99,18",
width=0.75];
}
a [height=0.5,
pos="63,162",
width=0.75];
b [height=0.5,
pos="63,90",
width=0.75];
a -> b [pos="e,63,108.1 63,143.7 63,136.41 63,127.73 63,119.54"];
b -> c [pos="e,35.304,35.147 54.65,72.765 50.425,64.548 45.192,54.373 40.419,45.093"];
b -> d [pos="e,90.696,35.147 71.35,72.765 75.575,64.548 80.808,54.373 85.581,45.093"];
}
```
TeX has a TikZ library named `graph drawing` to provide same feature.
```tex
\documentclass[tikz]{standalone}
\usetikzlibrary{arrows.meta, graphs, graphdrawing, shapes.geometric}
\usegdlibrary{layered}
\title{graph}
\begin{document}
\begin{tikzpicture}[rounded corners, >=Stealth, auto]
\graph[layered layout, nodes={draw, align=center}]{%
a -> b -> {c, d}
};
\end{tikzpicture}
\end{document}
```
Different from graphviz, you can use powerful TeX syntax in `graph drawing`.
Run `lx build` for
[this example](
https://github.com/ustctug/texrocks/tree/main/packages/demo-tikz):
This example only supports LuaTeX, not pdfTeX and XeTeX.
because `graph drawing` is written in lua, not TeX.
