Graphics, Figures & Tables ⇒ How to draw Chess Board?

[xaero7]

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\documentclass{article}
\usepackage{tikz}
\usepackage[active,tightpage]{preview} 
\PreviewEnvironment{tikzpicture}
\definecolor{fillcolor}{rgb}{0.008, 0.753, 0.353} %rgb(2, 192, 90)
\definecolor{drawcolor}{rgb}{0, 0.376, 0.173} %rgb(0, 96, 44)
\begin{document}
    \pagestyle{empty}
    
\begin{tikzpicture}
\tikzstyle{greenfill} = [fill=fillcolor!20, draw=drawcolor]
\tikzstyle{whitefill} = [fill=white, draw=drawcolor]
\filldraw[greenfill] (0,0) -- (1,0) -- (1,1) -- (0, 1) -- cycle;
\def\flag{0}
\foreach \x in {0, 1, 2, 3} {
    \foreach \y in {0, 1, 2, 3} {
        \ifnum \flag =0  {
            \filldraw[greenfill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
            \def\flag{1};
        }
        \else {
            \filldraw[whitefill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
            \def\flag{0};
        }       
        \fi     
    }
}
\end{tikzpicture}
    
\end{document}
 
 
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I'm trying to draw something like Chess Board, but it seems all the squares are green, no one is white!

how to modify?

QQ20160424104557.png (598 Bytes) Viewed 5208 times

[rais]

I'm trying to draw something like Chess Board, but it seems all the squares are green, no one is white!

Even without the additional braces in your \ifnum/\else statements, your \def\flag{..} is seen inside a group (from \foreach), thus your \flag reverts to 0 (what you set it to outside the group), whenever leaving the group (which \foreach \y in {...}{...} does for every value of \y).
You could use \gdef instead of \def to redefine \flag in a way that it keeps its new value even after leaving the group it was used in, but that would probably give you the desired effect only if you're using an odd number of values for \y---or if you toggle your \flag inside the \x-\foreach, as well.
Another idea would be to check both \x and \y values, if they're odd/even, then you don't need your \flag anymore:

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Code, edit and compile here:

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\documentclass{standalone}
\usepackage{tikz}
\definecolor{fillcolor}{rgb}{0.008, 0.753, 0.353} %rgb(2, 192, 90)
\definecolor{drawcolor}{rgb}{0, 0.376, 0.173} %rgb(0, 96, 44)
\begin{document}
           
\begin{tikzpicture}
\tikzstyle{greenfill} = [fill=fillcolor!20, draw=drawcolor]
\tikzstyle{whitefill} = [fill=white, draw=drawcolor]
\filldraw[greenfill] (0,0) -- (1,0) -- (1,1) -- (0, 1) -- cycle;
\foreach \x in {0, 1, 2, 3} {
  \foreach \y in {0, 1, 2, 3} {
    \ifodd\x
      \ifodd\y  % \x odd, \y odd
        \filldraw[greenfill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
      \else  % \x odd, \y even
        \filldraw[whitefill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
      \fi
    \else
      \ifodd\y  % \x even, \y odd
        \filldraw[whitefill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
      \else  % \x even, \y even
        \filldraw[greenfill] (\x, \y) -- (\x +1, \y) -- (\x +1, \y +1) -- (\x, \y +1) -- cycle;
      \fi
    \fi            
  }
}
\end{tikzpicture}
           
\end{document}
 
 
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XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Run LaTeX here

KR
Rainer

[xaero7]

Thank you very much! rais