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交点数

tag-icon • tag-icon tikz-pgf paths intersections path-clipping
交点数

在 pgfmanual p 132 的这个示例中，如何使用\t交点数外部\fill命令。我试过了\def\Nb{\t}，但没有用。

\begin{tikzpicture}
\clip (-2,-2) rectangle (2,2);
\draw [name path=curve 1] (-2,-1) .. controls (8,-1) and (-8,1) .. (2,1);
\draw [name path=curve 2] (-1,-2) .. controls (-1,8) and (1,-8) .. (1,2);
\fill [name intersections={of=curve 1 and curve 2, name=i, total=\t}]
      [red, opacity=0.5, every node/.style={above left, black, opacity=1}]
      \foreach \s in {1,...,\t}{(i-\s) circle (2pt) node {\footnotesize\s}};
\end{tikzpicture}

答案1

您可以使用\pgfextra{\xdef\Nb{\t}}或\pgfextra{\global\let\Nb\t}：

\documentclass[tikz]{standalone}
\usetikzlibrary{intersections}
\begin{document}
\begin{tikzpicture}
  \clip (-2,-2) rectangle (2,2);
  \draw [name path=curve 1] (-2,-1) .. controls (8,-1) and (-8,1) .. (2,1);
  \draw [name path=curve 2] (-1,-2) .. controls (-1,8) and (1,-8) .. (1,2);

  \path [name intersections={of=curve 1 and curve 2, name=i, total=\t}]
  \pgfextra{\xdef\Nb{\t}};

  \fill [red, opacity=0.5, every node/.style={above left, black, opacity=1}]
  \foreach \s in {1,...,\Nb}{(i-\s) circle (2pt) node {\footnotesize\s}};
\end{tikzpicture}
\end{document}

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