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我可以用散射源旋转标记吗？

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我可以用散射源旋转标记吗？

我希望能够用它pgfplots来展示滑雪者从滑雪坡上滑下来的情景。以下是我目前所做的工作。

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\makeatletter
\pgfkeyssetvalue{/pgf/shapes/ski/ski length}{1cm}
\pgfkeyssetvalue{/pgf/shapes/ski/ski radius}{.075cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg length}{.3cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg angle}{140}
\pgfkeyssetvalue{/pgf/shapes/ski/back length}{.5cm}
\pgfkeyssetvalue{/pgf/shapes/ski/head radius}{.1cm}
\pgfdeclareplotmark{skimark}{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{%
      \pgfpoint{+0pt}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{%
      \pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
        \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
}
\makeatother
\begin{document}
\begin{tikzpicture}
  \begin{axis}[domain = 0:5,
    ]
    \addplot+[mark = skimark,
              only marks,
              forget plot,
              scatter,
              scatter src = {-exp(-x)}] gnuplot[samples=5] {exp(-x)};
    \addplot+[no markers] gnuplot[samples=30] {exp(-x)};
  \end{axis}
\end{tikzpicture}
\end{document}

在此处输入图片描述

我如何使用散射源信息来旋转标记，以便滑雪者的滑雪板与斜坡平行（稍微移动一下也会很好，因为我犯了一个设计错误，没有定义滑雪板的原点...）？

注意：我ski也可以提供一个形状。

\pgfdeclareshape{ski}{%
  \anchor{center}{\pgfpointorigin}
  \savedanchor\bottomleg{%
    \pgfpoint{+0pt}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
  %
  \backgroundpath{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{\pgf@process{\bottomleg}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{\pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg
          angle}}{\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
    %
  }
}

答案1

不幸的是，我认为没有简单的方法来旋转情节标记。你可能需要打开一个功能要求为了这。

解决此问题的一种方法是使用scatter/@pre marker code对函数进行数值微分，并相应地旋转标记。要使此方法有效，您需要设置disabledatascaling或axis equal。

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\makeatletter
\pgfkeyssetvalue{/pgf/shapes/ski/ski length}{1cm}
\pgfkeyssetvalue{/pgf/shapes/ski/ski radius}{.075cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg length}{.3cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg angle}{140}
\pgfkeyssetvalue{/pgf/shapes/ski/back length}{.5cm}
\pgfkeyssetvalue{/pgf/shapes/ski/head radius}{.1cm}
\pgfdeclareplotmark{skimark}{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{%
      \pgfpoint{+0pt}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{%
      \pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
        \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
}
\makeatother


\begin{document}

\newcommand{\calcangle}[2]{
\def\x{#2-0.01}
\pgfmathsetmacro\fxone{#1}
\def\x{#2+0.01}
\pgfmathsetmacro\fxtwo{#1}
\pgfmathsetmacro\test{atan2(1,(\fxone-\fxtwo)/0.02*\pgfplotsunitylength/\pgfplotsunitxlength)}
}

\begin{tikzpicture}
  \begin{axis}[
    domain = 0:4,
    xmax=4,
    disabledatascaling,
    enlargelimits=true,
    ]
    \addplot+[mark = skimark,
              forget plot,
              scatter,
              mark phase=2, mark repeat=6,
              visualization depends on=x \as \rawx,
              scatter/@pre marker code/.append code={
                \calcangle{exp(-\x)}{\rawx}
                \pgftransformrotate{\test}
                \pgftransformyshift{1.1*\pgfkeysvalueof{/pgf/shapes/ski/leg length}}
              },]{exp(-x)};
  \end{axis}
\end{tikzpicture}
\end{document}

或者，您可以使用以下代码的改编版本：pgfplots - 将节点放置在绘图的 x 坐标上。目前它非常笨重，主要是因为您需要调整函数meta以便它生成 0:1000 范围内的数字。

但至少它有效......

在此处输入图片描述

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\usetikzlibrary{intersections}

\makeatletter
\pgfkeyssetvalue{/pgf/shapes/ski/ski length}{1cm}
\pgfkeyssetvalue{/pgf/shapes/ski/ski radius}{.075cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg length}{.3cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg angle}{140}
\pgfkeyssetvalue{/pgf/shapes/ski/back length}{.5cm}
\pgfkeyssetvalue{/pgf/shapes/ski/head radius}{.1cm}
\pgfdeclareshape{ski}{%
  \anchor{center}{\pgfpointorigin}
  \savedanchor\bottomleg{%
    \pgfpoint{+0pt}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
  %
  \backgroundpath{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{\pgf@process{\bottomleg}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{\pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg
          angle}}{\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
    %
  }
}


\tikzset{
    add skier at x/.style={
        name path global=plot line,
        /pgfplots/execute at end plot visualization/.append={
                \begingroup
            \path [name path global = position line #1-1]
                ({axis cs:#1,0}|-{rel axis cs:0,0}) --
                ({axis cs:#1,0}|-{rel axis cs:0,1});
            \path [xshift=1pt, name path global = position line #1-2]
                ({axis cs:#1,0}|-{rel axis cs:0,0}) --
                ({axis cs:#1,0}|-{rel axis cs:0,1});
            \path [
                name intersections={
                    of={plot line and position line #1-1},
                    name=left intersection
                },
                name intersections={
                    of={plot line and position line #1-2},
                    name=right intersection
                },
                label node/.append style={pos=1}
            ] (left intersection-1) -- (right intersection-1);
            \pgfmathparse{(-exp(-#1)+1)*1000} % This has to be changed according to the function generating the color value
            \pgfplotscolormapaccess[0:1000][1]{\pgfmathresult}{\pgfkeysvalueof{/pgfplots/colormap name}}
            \definecolor{mapped color}{rgb}{\pgfmathresult}
           \pgftransformarrow{\pgfpointanchor{left intersection-1}{center}}{\pgfpointanchor{right intersection-1}{center}}
           \node [ski, transform shape, yshift=1.1*\pgfkeysvalueof{/pgf/shapes/ski/leg length}, mapped color] {};
            \endgroup
        }
    }
}
\makeatother
\begin{document}
\begin{tikzpicture}
  \begin{axis}[domain = 0:5,
    ]
    \addplot[
        add skier at x=0.1,
        add skier at x=0.9,
        add skier at x=2.5,
        add skier at x=4
    ] {exp(-x)};

  \end{axis}
\end{tikzpicture}
\end{document}

答案2

请注意，由于使用了节点而不是标记，因此以下内容解决了问题但没有回答所提出的问题。

更新答案 （感谢@Jake 的评论和调试）

在此处输入图片描述

这里的关键思想是使用/pgfplots/scatter/@pre marker code/.append code。

首先，一些代码用于获取函数导数的值（通过密钥给出 scatter src，是的，需要明确给出导数），该值以\pgfplotsmeta数字形式存储fpu，因此必须先进行转换。结果是切线的斜率。

\pgfkeys{/pgf/fpu,pgf/fpu/output format=fixed}
\pgfmathparse{\pgfplotspointmeta}%
\pgfkeys{/pgf/fpu = false}
\edef\myslope{\pgfmathresult}%

然后\path必须将 设置为transparent，否则绘制的 会给出轴坐标系中切线的实际方向，这要归功于技巧axis direction cs。原点(0,0)与标记混淆。

\path[transparent] (0,0) -- node[opaque,sloped,at
start,draw,shape=ski,anchor=bottom leg] {} ++(axis
direction cs:1,\myslope);

现在，完整的代码。

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\makeatletter
\pgfkeyssetvalue{/pgf/shapes/ski/ski length}{1cm}
\pgfkeyssetvalue{/pgf/shapes/ski/ski radius}{.075cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg length}{.3cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg angle}{140}
\pgfkeyssetvalue{/pgf/shapes/ski/back length}{.5cm}
\pgfkeyssetvalue{/pgf/shapes/ski/head radius}{.1cm}

\pgfdeclareshape{ski}{%
  \anchor{center}{\pgfpointorigin}
  \savedanchor\bottomleg{%
    \pgf@x=0pt
    \pgf@y=-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}
  \anchor{bottom leg}{\bottomleg}
  %
  \backgroundpath{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{\pgf@process{\bottomleg}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{\pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg
          angle}}{\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
    %
  }
}
\makeatother
\begin{document}
\begin{tikzpicture}
  \begin{axis}[domain = 0:5,
    ]
    \addplot+[%
              % no markers,
              only marks,
              forget plot,
              scatter,
              /pgfplots/scatter/@pre marker code/.append code={%
                \pgfkeys{/pgf/fpu,pgf/fpu/output format=fixed}
                \pgfmathparse{\pgfplotspointmeta}%
                \pgfkeys{/pgf/fpu = false}
                \edef\myslope{\pgfmathresult}%
                \path[transparent] (0,0) -- node[opaque,sloped,at
                start,draw,shape=ski,anchor=bottom leg] {} ++(axis
                direction cs:1,\myslope);
              },
              scatter src = {cos(deg(x))}] gnuplot[samples=10] {sin(x)};
    \addplot+[no markers] gnuplot[samples=30] {sin(x)};
  \end{axis}
\end{tikzpicture}


\end{document}

第一个答案 （并非所有功能都适用，请参阅评论）

我找到了一种方法来做到这一点。正如@Jake所说，我不能依赖一阶导数的值来给出切线的角度，因为轴没有相同的单位（一般来说）。所以这个想法是使用技巧axis cs:来访问坐标系（然后访问轴的 x 和 y 单位）。最后，我没有使用任何标记，滑雪者被绘制为一个节点。幸运的是，绘制命令从标记中继承了所有图形参数（包括元颜色信息）。

在此处输入图片描述

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}
\makeatletter
\pgfkeyssetvalue{/pgf/shapes/ski/ski length}{1cm}
\pgfkeyssetvalue{/pgf/shapes/ski/ski radius}{.075cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg length}{.3cm}
\pgfkeyssetvalue{/pgf/shapes/ski/leg angle}{140}
\pgfkeyssetvalue{/pgf/shapes/ski/back length}{.5cm}
\pgfkeyssetvalue{/pgf/shapes/ski/head radius}{.1cm}

\pgfdeclareshape{ski}{%
  \anchor{center}{\pgfpointorigin}
  \savedanchor\bottomleg{%
    \pgf@x=0pt
    \pgf@y=-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}
  \anchor{bottom leg}{\bottomleg}
  %
  \backgroundpath{%
    % ski
    \pgfpathmoveto{\pgfpoint{-.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpoint{.5\pgfkeysvalueof{/pgf/shapes/ski/ski
          length}}{-\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpatharc{-90}{0}{\pgfkeysvalueof{/pgf/shapes/ski/ski radius}}
    \pgfsetlinewidth{.5mm}
    \pgfusepath{stroke}
    % body
    \pgfpathmoveto{\pgf@process{\bottomleg}}
    \pgfpathlineto{\pgfpointorigin}
    \pgfpathlineto{\pgfpointpolar{\pgfkeysvalueof{/pgf/shapes/ski/leg
          angle}}{\pgfkeysvalueof{/pgf/shapes/ski/leg length}}}
    \pgfpathlineto{\pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}
    \pgfsetroundjoin
    \pgfsetlinewidth{1mm}
    \pgfusepath{stroke}
    %
    \pgfpathcircle{%
      \pgfpointadd{%
        \pgfpointpolar{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg angle}}{%
          \pgfkeysvalueof{/pgf/shapes/ski/leg length}}}{% 
        \pgfpoint{%
          \pgfkeysvalueof{/pgf/shapes/ski/back length}}{+0pt}}}{%
      \pgfkeysvalueof{/pgf/shapes/ski/head radius}}
    \pgfusepath{fill}
    %
  }
}
\makeatother
\begin{document}
\begin{tikzpicture}
  \begin{axis}[domain = 0:5,
    ]
    \addplot+[no markers,
              only marks,
              forget plot,
              scatter,
              /pgfplots/scatter/@pre marker code/.append code={%
                \pgfkeys{/pgf/fpu,pgf/fpu/output format=fixed}
                \pgfmathparse{\pgfplotspointmeta}%
                \pgfkeys{/pgf/fpu = false}
                \edef\myslope{\pgfmathresult}%
                \path[transparent] (axis cs:0,0) -- node[opaque,sloped,at
                start,draw,shape=ski,anchor=bottom leg] {} (axis cs:1,\myslope);
              },
              scatter src = {-exp(-x)}] gnuplot[samples=5] {exp(-x)};
    \addplot+[no markers] gnuplot[samples=30] {exp(-x)};
  \end{axis}
\end{tikzpicture}
\end{document}

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