8

I tried to use the fillbetween library of pgfplots to fill the intersection of two circles. However I get it with "inverted" colors:

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}

\begin{document}

  \begin{tikzpicture}
    \begin{axis}[axis equal,no markers,hide axis,samples=100]
      \addplot+[domain=360:0,name path=k1] ({1.5*cos(x)},{1.5*sin(x)});
      \addplot+[domain=360:0,name path=k2] ({cos(x) + 2},{sin(x)});
      \addplot[blue!50] fill between[of=k2 and k1];
    \end{axis}
  \end{tikzpicture}


\end{document}

Output:

Output

The white area should be blue and the blue area white. Why does pgfplots fill it this way? How can I fix it?

student
  • 29,003

2 Answers2

10

You can use intersection segments:

\documentclass[margin=5pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.11}
\usepgfplotslibrary{fillbetween}
\begin{document}
  \begin{tikzpicture}
%
    \pgfdeclarelayer{pre main}
    \pgfsetlayers{pre main,main}
%
    \begin{axis}[axis equal,no markers,hide axis,samples=100]
      \addplot+[domain=360:0,name path=k1] ({1.5*cos(x)},{1.5*sin(x)});
      \addplot+[domain=360:0,name path=k2] ({cos(x) + 2},{sin(x)});
%
      \begin{pgfonlayer}{pre main}
        \fill [orange!50,
          intersection segments={
            of=k1 and k2,
            sequence={L0--L1--R2}
          }];
      \end{pgfonlayer}
%
    \end{axis} 
  \end{tikzpicture}
\end{document}

enter image description here

To show the intersection segments:

enter image description here

So the green (L0), orange (L1) and yellow (R2) segments are needed in the sequence to fill the intersection of the two cirles.

Code:

\documentclass[margin=5pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.11}
\usepgfplotslibrary{fillbetween}
\begin{document}
  \begin{tikzpicture}
    \pgfdeclarelayer{pre main}
  \pgfsetlayers{pre main,main}
    \begin{axis}[axis equal,no markers,hide axis,samples=100]
      \addplot+[domain=360:0,name path=k1] ({1.5*cos(x)},{1.5*sin(x)});
      \addplot+[domain=360:0,name path=k2] ({cos(x) + 2},{sin(x)});
%
      \begin{scope}[line width=2pt]
        \foreach[count=\i from 0] \c in {green,orange,purple}{
          \edef\temp{\noexpand\draw [\c,
            intersection segments={of=k1 and k2,sequence={L\i}}]node[right]{L\i};}
          \temp}
        \foreach[count=\i from 0] \c in {blue,gray,yellow}{
          \edef\temp{\noexpand\draw [\c,
            intersection segments={of=k1 and k2,sequence={R\i}}]node[left]{R\i};}
          \temp}
      \end{scope}
%
  \end{axis} 
  \end{tikzpicture}
\end{document}
esdd
  • 85,675
3

Thanks to the link posted by @fpast the following code works: 

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}

\begin{document}

  \begin{tikzpicture}
    \begin{axis}[axis equal,no markers,hide axis,samples=100]
      \addplot+[domain=360:0,name path=k1,fill=blue] ({1.5*cos(x)},{1.5*sin(x)});
      \addplot+[domain=360:0,name path=k2,fill=blue] ({cos(x) + 2},{sin(x)});
      \tikzfillbetween[of=k1 and k2]{white};     
    \end{axis}
  \end{tikzpicture}


\end{document}

But I don't think that this is the most elegant solution.

Output:

Output

student
  • 29,003