TikZ how to temporarily discontinue line at intersection of two lines

intersectionslineshapestikz-pgf

I am working in TikZ and I am trying to make one line stop, then start again before and after the intersection with another line. I have attempted to put a node at the intersection point and filled it with white, but this has cut both lines. I only want the blue line to break and the black line to continue. Any help would be great!

Here's what the following code does:

\documentclass{article}
\usepackage[dvipsnames]{xcolor}
\usepackage{tikz}%
\usetikzlibrary{arrows.meta,shapes.misc, positioning, shapes.geometric, intersections}%

\begin{document}
   \begin{tikzpicture}
    \draw [-Latex, RoyalBlue, name path = b1] (0,-1) -- (10,-1);
    \draw [-Latex, RoyalBlue, name path = b2] (0,-0.5) -- (10,-0.5);
    \draw [-Latex, RoyalBlue, name path = b3] (0,0) -- (10,0);
    \draw [-Latex, RoyalBlue, name path = b4] (0,0.5) -- (10,0.5);
    \draw [-Latex, RoyalBlue, name path = b5] (0,1) -- (10,1);

    \node[trapezium,
    draw = black,
    thick,
    rotate=90,
    minimum width = 2.5cm,
    minimum height= 1cm,
    trapezium left angle = 100,
    trapezium right angle = 80,
    trapezium stretches=true,
    trapezium stretches body =true,
    name path = trap1] (t) at (1,0) {};
    
    \draw[name intersections={of=b1 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b2 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b3 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b4 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b5 and trap1}] (intersection-1) node[fill=white] {};
    \end{tikzpicture}
\end{document}

Best Answer

I know it is only a workaround but you could use that node twice: first for intersections, and second to actually draw it.

To make things a bit easier you can also add a style for the node so you can reuse it any time you need. The same can be done with coordinates, such that such you can have named coordinates for multiple usage.

\documentclass{article}
\usepackage[dvipsnames]{xcolor}
\usepackage{tikz}%
\usetikzlibrary{arrows.meta,shapes.misc, positioning, shapes.geometric, intersections}%

\tikzset{
    tnode/.style = {
        trapezium,
        thick,
        rotate=90,
        minimum width = 2.5cm,
        minimum height= 1cm,
        trapezium left angle = 100,
        trapezium right angle = 80,
        trapezium stretches=true,
        trapezium stretches body =true,
        name path = trap1,
    },
 }


\begin{document}
   \begin{tikzpicture}
    \coordinate (ct) at (1,0);
    \node[tnode] (t) at (ct) {};
    
    \draw [-Latex, RoyalBlue, name path = b1] (0,-1) -- (10,-1);
    \draw [-Latex, RoyalBlue, name path = b2] (0,-0.5) -- (10,-0.5);
    \draw [-Latex, RoyalBlue, name path = b3] (0,0) -- (10,0);
    \draw [-Latex, RoyalBlue, name path = b4] (0,0.5) -- (10,0.5);
    \draw [-Latex, RoyalBlue, name path = b5] (0,1) -- (10,1);

    \draw[name intersections={of=b1 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b2 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b3 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b4 and trap1}] (intersection-1) node[fill=white] {};
    \draw[name intersections={of=b5 and trap1}] (intersection-1) node[fill=white] {};

    \node [tnode, draw] at (ct) {};
\end{tikzpicture}
\end{document}

EDIT. Example based on scope and the background layer.

\documentclass{article}
\usepackage[dvipsnames]{xcolor}
\usepackage{tikz}

\usetikzlibrary{
    arrows.meta,
    shapes.misc,
    positioning,
    shapes.geometric,
    intersections,
    backgrounds,        % For a background layer
}


\begin{document}
   \begin{tikzpicture}
    \node[
        trapezium,
        draw = black,
        thick,
        rotate=90,
        minimum width = 2.5cm,
        minimum height= 1cm,
        trapezium left angle = 100,
        trapezium right angle = 80,
        trapezium stretches=true,
        trapezium stretches body =true,
        name path = trap1,
    ] (t) at (1,0) {};

    \begin{scope}[on background layer]
        \foreach \c [evaluate=\c as \y using {\c/2}] \n in {-2,...,2} {
            \draw [-Latex, RoyalBlue, name path={b\c}] (0,\y) -- (10,\y);
            \path [name intersections={of={b\c} and trap1, name=i}] (i-1) node[fill=white] {};
        };
    \end{scope}
\end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] TikZ: Intersection of two lines

The reason the code does not work as provided is that there is only one intersection, and so (intersection-2) does not exist. One way to alleviate this kind of issue is to specify total=\t to contain the total number of intersections and the use a foreach to loop through each intersection:

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

\begin{document}
\begin{tikzpicture}[every node/.style={black,above right}]
\draw[name path=line 1] (0,0) -- (2,2);
\draw[name path=line 2] (2,0) -- (0,2);
\fill[red,name intersections={of=line 1 and line 2,total=\t}]
    \foreach \s in {1,...,\t}{(intersection-\s) circle (2pt) node {\footnotesize\s}};
\end{tikzpicture}
\end{document}

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

The source of the difficulty is that ellipses are constructed in a particular way in TikZ. They are paths that start from the x-axis and proceed counter-clockwise around their centre. The vast majority of the time, the exact parametrisation doesn't matter. You appear to have found the one situation where it does!

In the actual question, you only want to be able to mirror the ellipse, and so draw it starting from the negative x-axis (the title of the question suggests a more flexible approach). That's actually not too hard since we can exploit the symmetry of the ellipse. The key is to provide it with a negative x-radius, since then it will start from the negative x-axis (and proceed clockwise, but we could correct for that by negating the y-radius as well). To do this, we interrupt the call from the node shape to the drawing command and flip the sign of the x-radius. The simplest way to do this is to redefine the \pgfpathellipse macro to do the negation and then call the original macro. The following code does this.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations,shapes,decorations.markings}
\makeatletter
\let\origpgfpathellipse=\pgfpathellipse
\def\revpgfpathellipse#1#2#3{%
  #2%
  \pgf@xa=-\pgf@x
  \origpgfpathellipse{#1}{\pgfqpoint{\pgf@xa}{0pt}}{#3}}
\makeatother

\tikzset{
  reversed ellipse/.style={
    ellipse,
    reverse the ellipse%
  },
  reverse the ellipse/.code={
    \let\pgfpathellipse=\revpgfpathellipse
  }
}
\begin{document}
\begin{tikzpicture}
\node[ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,0) {hello world};

\node[reversed ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,-2) {hello world};
\end{tikzpicture}

\end{document}

Here's the result:

rotated ellipse

(the arrow got clipped, but you can see where it lies)

Best Answer

Related Solutions

[Tex/LaTex] TikZ: Intersection of two lines

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

Related Question