如何在 TikZ 中沿曲线在特定位置绘制一个点

Question

我得到了一个很好的代码来画一个箭 在曲线的中间位置。从Tikz：箭头位于中心

\tikzset{->-/.style={decoration={
 markings,
 mark=at position .5 with {\arrow{>}}},postaction={decorate}}}

我不知道如何制作点位于曲线的某处。

代码可能看起来像......（-dot-是不是在职的）

\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}

\begin{document}
\tikzset{->-/.style={decoration={
  markings,
  mark=at position #1 with {\arrow{>}}},postaction={decorate}}}

\tikzset{-dot-/.style={decoration={
  markings,
  mark=at position #1 with {\fill circle (2pt)}},postaction={decorate}}}

\begin{tikzpicture}
%\fill (2,2) circle (2pt);
 \draw[->-=.5] (0,0) to [bend left] (2,4);
 \draw[-dot-=.8] (0,0) to [bend right] (2,4);
\end{tikzpicture}

\end{document} 

新答案：

现在我得到了一个非常简单的解决方案（感谢来自提取TikZ中曲线上任意点的x，y坐标)：

\documentclass{article}
\usepackage{tikz}
%
\begin{document}
%
\begin{tikzpicture}
\draw (0,0) to [bend left=20]  coordinate[pos=0.7] (A)(2,4);
\fill[blue] (A) circle (2pt);
\end{tikzpicture}
%
\end{document}

Answer 1

似乎你漏掉了一个;。MWE\fill circle (2pt);将是

\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}

\begin{document}
\tikzset{->-/.style={decoration={
  markings,
  mark=at position #1 with {\arrow{>}}},postaction={decorate}}}

\tikzset{-dot-/.style={decoration={
  markings,
  mark=at position #1 with {\fill circle (2pt);}},postaction={decorate}}} %%% in this line added a ;

\begin{tikzpicture}
%\fill (2,2) circle (2pt);
 \draw[-dot-=.5] (0,0) to [bend left] (2,4);
 \draw[-dot-=.8] (0,0) to [bend right] (2,4);
\end{tikzpicture}

\end{document} 

Answer 2

有一个箭头，它是一个点，因此您可以使用它并使用语法\arrow。您需要加载箭头库才能使用它。

\documentclass{scrartcl}
%\url{http://tex.stackexchange.com/q/56347/86}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.markings}

\begin{document}
\tikzset{->-/.style={decoration={
  markings,
  mark=at position #1 with {\arrow{>}}},postaction={decorate}}}

\tikzset{-dot-/.style={decoration={
  markings,
  mark=at position #1 with {\arrow{*}}},postaction={decorate}}}

\begin{tikzpicture}
%\fill (2,2) circle (2pt);
 \draw[->-=.5] (0,0) to [bend left] (2,4);
 \draw[-dot-=.8] (0,0) to [bend right] (2,4);
\end{tikzpicture}

\end{document}

通过一些小技巧（不推荐），可以将其设置为增强箭头规范。回想一下，将->可选参数放入命令中会在末尾\draw安装箭头。通过修改此代码，我们可以将其设置为在中间或曲线上的某个指定点放置一个点。>-*-

\documentclass{scrartcl}
%\url{http://tex.stackexchange.com/q/56347/86}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.markings}

\makeatletter
\def\tikz@@processarrows#1-#2\@nil{%
  \expandafter\ifx\csname tikz@special@arrow@start#1\endcsname\relax%
    \pgfsetarrowsstart{#1}
  \else%
    \pgfsetarrowsstart{\csname tikz@special@arrow@start#1\endcsname}%
  \fi%
  \pgfutil@in@-{#2}%
  \ifpgfutil@in@%
  % has a midpoint specification
  \tikz@@processmidarrow#2\@nil
  \else
  \expandafter\ifx\csname tikz@special@arrow@end#2\endcsname\relax%
    \pgfsetarrowsend{#2}
  \else%
    \pgfsetarrowsend{\csname tikz@special@arrow@end#2\endcsname}%
  \fi%
  \fi
}

\def\tikz@@processmidarrow#1-#2\@nil
{
  \expandafter\ifx\csname tikz@special@arrow@end#2\endcsname\relax%
    \pgfsetarrowsend{#2}
  \else%
    \pgfsetarrowsend{\csname tikz@special@arrow@end#2\endcsname}%
  \fi%
  \def\tikz@temp{#1}%
  \ifx\tikz@temp\pgfutil@empty%
  \else%
    \ifx\tikz@value\pgfutil@empty
    \else
      \tikzset{arrow midpoint location/.expand once=\tikz@value}
    \fi
    \tikzset{arrow midpoint=#1}
  \fi%
}
\tikzset{
  arrow midpoint location/.initial=.5,
  arrow midpoint/.style={decoration={
  markings,
  mark=at position \pgfkeysvalueof{/tikz/arrow midpoint location} with {\arrow{#1}}},postaction={decorate}}}

\pgfkeys{/tikz/.unknown/.code=%
  % Is it a pgf key?
  \let\tikz@key\pgfkeyscurrentname% 
  \def\tikz@value{#1}%
  \pgfkeys{/pgf/\tikz@key/.try={#1}}%
  \ifpgfkeyssuccess%
  \else%
    \expandafter\pgfutil@in@\expandafter!\expandafter{\tikz@key}%
    \ifpgfutil@in@%
      % this is a color!
      \expandafter\tikz@addoption\expandafter{\expandafter\pgfutil@color\expandafter{\tikz@key}}%
      \edef\tikz@textcolor{\tikz@key}%
    \else%
      \pgfutil@doifcolorelse{\tikz@key}
      { %     
        \expandafter\tikz@addoption\expandafter{\expandafter\pgfutil@color\expandafter{\tikz@key}}%
        \edef\tikz@textcolor{\tikz@key}%
      }%
      {%
        % Ok, second chance: This might be an arrow specification:
        \expandafter\pgfutil@in@\expandafter-\expandafter{\tikz@key}
        \ifpgfutil@in@%
          % Ah, an arrow spec!
          \expandafter\tikz@processarrows\expandafter{\tikz@key}%
        \else%
          % Ok, third chance: A shape!
          \expandafter\ifx\csname pgf@sh@s@\tikz@key\endcsname\relax%
            \pgfkeys{/errors/unknown key={/tikz/\tikz@key}{#1}}%
          \else%
            \edef\tikz@shape{\tikz@key}%
          \fi%
        \fi%
      }%
    \fi%
  \fi%
}

\makeatother

\begin{document}

\begin{tikzpicture}
 \draw[*-] (0,0) -- (2,4);
 \draw[->-] (0,0) to [bend left] (2,4);
 \draw[-*->=0.8] (0,0) to [bend right] (2,4);
\end{tikzpicture}

\end{document}