How to draw rounded corner grid in tikz

Question

As the title describes, I want only the biggest rectangle to have rounded corners.

This is my code now

\begin{tikzpicture}[cell/.style={rectangle,draw=black,thin, minimum size=0.4cm}]
    \begin{scope}
        \node[cell,fill=red!20] at (0,0) {};
        \node[cell,fill=red!20] at (0.8,0) {};
        \node[cell,fill=red!20] at (0.4,0.4) {};
        \node[cell,fill=red!20] at (0,0.8) {};
        \node[cell,fill=red!20] at (0.8,0.8) {};
    \node[cell,fill=blue!30] at (0.4,0) {};
    \node[cell,fill=blue!30] at (0,0.4) {};
    \node[cell,fill=blue!30] at (0.8,0.4) {};
    \node[cell,fill=blue!30] at (0.4,0.8) {};

\end{scope}
\end{tikzpicture}

I also wonder if there is a easier way to fill the grid with customized colors.

Why do you have scope if it's not defining a demarcated part of the tikzpicture? — Plergux, Mar 18 '21 at 12:00
I only picked out a fraction of my code and delete the 'shift'. — namespace-Pt, Mar 18 '21 at 12:02
I think the answer has to do with this https://tex.stackexchange.com/a/32869/90297 — Elad Den, Mar 18 '21 at 13:37
Would you like to write something into the nodes afterwards or do you just want this grid like this? If the latter, then just draw and fill, without using nodes. — SebGlav, Mar 18 '21 at 17:53

score 4 · Accepted Answer · answered Mar 18 '21 at 18:02

A simple solution without nodes, like said in my comment above:

\documentclass[tikz,border=3.141592mm]{standalone}
\usetikzlibrary{calc}
\begin{document}
    \begin{tikzpicture}[line width=1pt]
    \coordinate (A) at (0,0);
    \def\l{1} % length of one third of the grid

    \draw[rounded corners=3pt,fill=red!20] (A) rectangle++ (3*\l,3*\l);
    \foreach \x/\y in {1/0,0/1,1/2,2/1}
        \draw[fill=blue!20] ($(A)+(\x,\y)$) rectangle++ (\l,\l);

\end{tikzpicture}

\end{document}

This is perfectly what I want, thank you SebGlav. – namespace-Pt Mar 19 '21 at 02:34 — namespace-Pt, Mar 19 '21 at 02:34

How to draw rounded corner grid in tikz

1 Answers1