從節點開始繪製垂直線，直到到達水平線

Question

請考慮這段程式碼

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,intersections}

\begin{document}
    \begin{tikzpicture}[node distance=-\pgflinewidth]   
        \node[fill=black] (a) {};
        \node[fill=black, xshift=\linewidth] (c) {};
        \node[xshift=\linewidth*0.7] (b) {...};

        \draw [name path=line1] (a) -- (b);
        \draw (b) -- (c);

        \node[draw, rectangle, above=of a, yshift=0.5cm, xshift=1cm] (foo1) {Foo 1};
        \node[draw, rectangle, right=0.5cm of foo1] (foo2) {Foo 2};

        \draw (foo1) -- TODO;
        \draw (foo2) -- TODO;
    \end{tikzpicture}

\end{document}

我無法從節點 foo1 和 foo2 向下繪製一條垂直直線到路徑 line1。我不想給出絕對座標。我試圖用交叉點來解決這個問題，但由於我的起始位置是一個節點，這似乎不起作用。有什麼建議麼？

Answer 1

像這樣？

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,intersections}

\begin{document}
    \begin{tikzpicture}[node distance=-\pgflinewidth]   
        \node[fill=black] (a) {};
        \node[fill=black, xshift=\linewidth] (c) {};
        \node[xshift=\linewidth*0.7] (b) {...};

        \draw [name path=line1] (a) -- (b);
        \draw (b) -- (c);

      \node[draw, rectangle, above=of a, yshift=0.5cm, xshift=1cm] (foo1) {Foo 1};
        \node[draw, rectangle, right=0.5cm of foo1] (foo2) {Foo 2};

\path[name path=fl1] (foo1.270)coordinate(f1)--++(-90:2);
\path[name path=fl2] (foo2.270)coordinate(f2)--++(-90:2);
\path[name intersections={of=fl1 and line1,by={a}}];
\path[name intersections={of=fl2 and line1,by={b}}];
\draw (f1)--(a);
\draw (f2)--(b);

%        \draw (foo1) -- TODO;
   %     \draw (foo2) -- TODO;
    \end{tikzpicture}

\end{document}

Answer 2

TikZ 可讓您定位位於穿過的水平線a和您正在尋找的垂直線的交點處的點foo1是語法(foo1|-a)或兩者都與語法(a-|foo1)。

我引用TikZ 3.1.4手冊

一般來說， 的意思(p |- q)是p垂直線通過與水平線通過的交點q。

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,intersections}

\begin{document}
    \begin{tikzpicture}[node distance=-\pgflinewidth]   
        \node[fill=black] (a) {};
        \node[fill=black, xshift=\linewidth] (c) {};
        \node[xshift=\linewidth*0.7] (b) {...};

        \draw [name path=line1] (a) -- (b);
        \draw (b) -- (c);

        \node[draw, rectangle, above=of a, yshift=0.5cm, xshift=1cm] (foo1) {Foo 1};
        \node[draw, rectangle, right=0.5cm of foo1] (foo2) {Foo 2};

        \draw (foo1) -- (a-|foo1);
        \draw (foo2) -- (a-|foo2);
    \end{tikzpicture}
\end{document}