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运动轨迹般的线条

tag-icon • tag-icon tikz-pgf
运动轨迹般的线条

是否可以使用tikz样式来自动执行下列操作？

\documentclass[tikz,border=1cm]{standalone}
\usetikzlibrary{calc}
\begin{document}    

\begin{tikzpicture}[
    plotmark/.style = {%
    draw, fill=lightgray, circle, inner sep=0pt, minimum size=4pt
  }
]
\coordinate (A) at (0,0);
\coordinate (B) at (0,7);
\coordinate (C) at (7,5);
\coordinate (AnBC) at ($(B)!(A)!(C)$);

\draw (B)--(C);
\draw (A)--(AnBC);
\draw[gray!10] (A)--(C);
\draw[gray!25] (A)--($(B)!0.8!(C)$);
\draw[gray!50] (A)--($(B)!0.6!(C)$);
\draw[gray!75] (A)--($(B)!0.4!(C)$);

\node[plotmark, label={below left:$A$}] at (A) {};
\node[plotmark, label={above left:$B$}] at (B) {};
\node[plotmark, label={above right:$C$}] at (C) {};

\end{tikzpicture}
\end{document}

在此处输入图片描述

在两个给定点之间，我应该能够确定线条的数量，并以增加的不透明度绘制线条。类似于：

\draw[motion lines={lines=4, start opacity=0.2, end opacity=1, color=blue} (C)--(AnBC);

答案1

TeXnician 已经告诉过你最重要的要素：循环当然，你可以定义使用此类循环的样式。我尽可能遵循了你对语法的说明，因此你可以这样做

 \draw[blue,set motion lines={lines=4,start opacity=0.2},rays=from A to line from C to AnBC];

平均能量损失

\documentclass[tikz,border=1cm]{standalone}
\usetikzlibrary{calc}
\begin{document}    

\begin{tikzpicture}[
    plotmark/.style = {%
    draw, fill=lightgray, circle, inner sep=0pt, minimum size=4pt
  },rays/.style args={from #1 to line from #2 to #3}{insert path={
   foreach \X  in {0,...,\pgfkeysvalueof{/tikz/motion lines/lines}}
  {[/utils/exec=\pgfmathsetmacro{\myopa}{\pgfkeysvalueof{/tikz/motion lines/start opacity}
  +(\pgfkeysvalueof{/tikz/motion lines/end opacity}-\pgfkeysvalueof{/tikz/motion lines/start opacity})
  *\X/\pgfkeysvalueof{/tikz/motion lines/lines}}]
  (#1) edge[opacity=\myopa] ($(#2)!{\X/\pgfkeysvalueof{/tikz/motion lines/lines}}!(#3)$)}}},
  set motion lines/.code={\tikzset{motion lines/.cd,#1}},
  motion lines/.cd,
  lines/.initial=5,
  start opacity/.initial=0.1,
  end opacity/.initial=1,
  ]
 \coordinate (A) at (0,0);
 \coordinate (B) at (0,7);
 \coordinate (C) at (7,5);
 \coordinate (AnBC) at ($(B)!(A)!(C)$);
 \draw (B)--(C);
 \draw[dotted,rays=from A to line from C to AnBC];
 \node[plotmark, label={below left:$A$}] at (A) {};
 \node[plotmark, label={above left:$B$}] at (B) {};
 \node[plotmark, label={above right:$C$}] at (C) {};
 \begin{scope}[xshift=10cm]
  \coordinate (A) at (0,0);
  \coordinate (B) at (0,7);
  \coordinate (C) at (7,5);
  \coordinate (AnBC) at ($(B)!(A)!(C)$);
  \draw (B)--(C);
  \draw[blue,set motion lines={lines=4,start opacity=0.2},rays=from A to line from C to AnBC];
  \node[plotmark, label={below left:$A$}] at (A) {};
  \node[plotmark, label={above left:$B$}] at (B) {};
  \node[plotmark, label={above right:$C$}] at (C) {};
 \end{scope}
\end{tikzpicture}
\end{document}

在此处输入图片描述

答案2

一种简单的基于循环的方法：

灰色路径

\documentclass[tikz,border=1cm]{standalone}
\usetikzlibrary{calc}
\begin{document}    

\begin{tikzpicture}[
    plotmark/.style = {%
    draw, fill=lightgray, circle, inner sep=0pt, minimum size=4pt
  }
]
\coordinate (A) at (0,0);
\coordinate (B) at (0,7);
\coordinate (C) at (7,5);
\coordinate (AnBC) at ($(B)!(A)!(C)$);

\draw (B)--(C);
\draw (A)--(AnBC);
\pgfmathtruncatemacro\parts{5}
\foreach \tikzi in {1,...,\parts} {
  \pgfmathtruncatemacro\colorspec{100-10*\tikzi}
  \draw[gray!\colorspec] (A) -- ($(AnBC)!\tikzi/\parts!(C)$);
}

\node[plotmark, label={below left:$A$}] at (A) {};
\node[plotmark, label={above left:$B$}] at (B) {};
\node[plotmark, label={above right:$C$}] at (C) {};

\end{tikzpicture}
\end{document}

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