# TiKz and tikz-grph background of Graph

the following code turns out well

\documentclass{minimal}

\usepackage{tikz}
\usepackage{tkz-graph}

\usetikzlibrary{backgrounds}

\begin{document}
\begin{tikzpicture}[yscale=-.75,xscale=1]
\GraphInit[vstyle=Empty]
\Vertex[L=$1$]{1}
\SOEA[L=$2$](1){2}
\SOEA[L=$3$](2){3}

\SOWE[L=$0$](3){14}
\SOEA[L=$4$](3){24}

\SOWE[L=$3$](24){15}
\SOEA[L=$5$](24){25}

\SOWE[L=$2$](15){16}
\SOEA[L=$4$](15){26}

\SOWE[L=$1$](16){17}
\SOEA[L=$3$](16){27}

\SOWE[L=$2$](27){18}
\SOEA[L=$0$](27){28}

\SOEA[L=$3$](18){19}
\SOEA[L=$4$](19){110}
\SOEA[L=$5$](110){111}

\Edges(1,2,3,24,25,26,27,28,19,110,111)
\Edges(3,14,15,24)
\Edges(26,15,16,27)
\Edges(19,18,17,16,27,18)

\draw[rounded corners=1em,line width=1.5em,black,opacity=0.2,cap=round]
(1.center) -- (2.center) -- (3.center) -- (24.center) -- (25.center) (3.center) -- (14.center);
\end{tikzpicture}
\end{document}


Like so:

Now I would like to add some more backgrounds: I tried to depict that with... Paint:

It shall look like the grey background grew further to 3 and then 4. I'd like to have it the same color and same style (with rounding aso.) like the "initial" one, except that it has a small rounded gap. Hope my mouse-drawing skills suffice to make my desire clear.

• Please make sure that your code compiles without errors. The first node is called l instead of 1, which causes errors later on. It also always nice if you make examples into complete documents so that it can be copy-pasted into an editor and compiled without any modification. Aug 3 '16 at 15:22
• there you go. any solutions? Aug 3 '16 at 15:40
• Was more a general comment, but I did think of one possible approach, see below. Aug 3 '16 at 19:01

Here's a brute force approach. I draw the shading in the same way as you have done already, then draw a white ellipse over the lower left vertex to simulate the line ending. For the lower of the two new segments I drew a line instead of a circle, to get an even gap all the way.

I also set the VertexStyle explicitly instead of using \GraphInit[vstyle=Empty] to remove the white fill that is used by default.

\documentclass[border=5mm]{standalone}

\usepackage{tikz}
\usepackage{tkz-graph}

\usetikzlibrary{backgrounds}

\begin{document}
\begin{tikzpicture}[
yscale=-.75,
VertexStyle/.style={} % removes white fill from vertices
]

\Vertex[L=$1$]{1}
\SOEA[L=$2$](1){2}
\SOEA[L=$3$](2){3}

\SOWE[L=$0$](3){14}
\SOEA[L=$4$](3){24}

\SOWE[L=$3$](24){15}
\SOEA[L=$5$](24){25}

\SOWE[L=$2$](15){16}
\SOEA[L=$4$](15){26}

\SOWE[L=$1$](16){17}
\SOEA[L=$3$](16){27}

\SOWE[L=$2$](27){18}
\SOEA[L=$0$](27){28}

\SOEA[L=$3$](18){19}
\SOEA[L=$4$](19){110}
\SOEA[L=$5$](110){111}

\Edges(1,2,3,24,25,26,27,28,19,110,111)
\Edges(3,14,15,24)
\Edges(26,15,16,27)
\Edges(19,18,17,16,27,18)

\begin{scope}[
on background layer, % everything in the environment is drawn behind the vertices
highlight/.style={rounded corners=1em,line width=1.5em,black,opacity=0.2,cap=round} % same settings you had, in a style for easier reuse
]

\draw [highlight] (15.center) -- (26.center); % draw top shading
\fill [white] (15.center) circle[x radius=1.em,y radius=1.em/0.75]; % draw white circle on top of the lower left vertex
\draw [highlight] (15.center) -- (14.center); % repeat for next segment
\draw [white,cap=round,line width=2em] (14.center) -- (3.center); %

• Thats already pretty close to what I'd like to have. Thanks. But is it possible to get the gap evenly spaced? I really would like to stick to the yscale=-.75 but even with yscale=-1 the spacing next to 0 doesnt look that good. Aug 3 '16 at 19:24