[Tex/LaTex] TikZ, placing nodes with “below of” and perpendicular coordinates

tikz-pgf

TikZ lets making

\node (node2) [below of = node2,some options] {textlabel};

and also lets using perpendicular coordinates:

\draw[some options] (node2.south) -- (node1.east -| node3.south);

But the joint use of below and perpendicular coordinates doesn't work:

\node (node2) [below of = (node1.east -| node3.south),some options] {textlabel};

Is it about syntax, or is it not possible at all?

And if it is not possible, how to place a node relative to some perpendicular coordinates?

I would obviously like to avoid creating a node at (node1.east -| node3.south) and then using its name.

Best Answer

AFAIK below of expects a node name and does not support calculations. An alternative is library positioning, e.g.:

\documentclass[tikz]{standalone}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[every node/.style={draw}]
  \node (A) at (0, 0) {A};
  \node (B) at (1, 1) {B};
  \node[below=0mm of A.east |- B.south] {C};
\end{tikzpicture}
\end{document}

If 0mm is omitted, the distance configured by option node distance is used.

Related Solutions

tikz-pgf – Optimal Methods for Intersections and Calculations with Relative Coordinates in TikZ

Before trying to answer your questions, I'd like to make it clear that this is all based on experiment and in trying to follow what goes on through the code. So it's a guess - hopefully and intelligent one, though.

Is it possible to use relative coordinates in the intersection syntax (a -| b)?

Not really. What happens is that TikZ sees the -| and assumes that the syntax is (coordinate -| coordinate). It then passes the coordinates back to the parser, but it does so as (coordinate) (since in the -| syntax there are no brackets around the coordinates).

However, there is nothing stopping you defining a new coordinate system which is effectively a relative coordinate system. One has to be a bit careful with groupings since TikZ parses a coordinate by looking for clues and the order in which it does them is therefore important.
Is there some way (macro or other) to access the current coordinate of the current path?

Not to my knowledge but it is very easy to define one.
Is it possible to use relative coordinates in the calculation syntax ($(a) + (b)$)?

No, but once you have a \currentcoordinate macro then it's easy to use this to make relative coordinates, and once you have an extra relative coordinate system then this can be used as well.
Is there a way to combine x-Part of one coordinate with the y-Part of another, other than the (a -| b) syntax? Can it be used with relative coordinates?

Yes! (At last) This can be done using the let syntax (Section 14.15 of the PGF manual, version 2.10).

Here's an example with lots of the above. It's not stress-tested so there may be things that don't work when put in more advanced situations.

\documentclass{article}
%\url{http://tex.stackexchange.com/q/53734/86}
\usepackage{tikz}
\usetikzlibrary{calc}

\makeatletter
\newcommand\currentcoordinate{\the\tikz@lastxsaved,\the\tikz@lastysaved}

\tikzdeclarecoordinatesystem{+}{%
  \tikz@scan@one@point\pgfutil@firstofone+(#1)%
}

\makeatother

\begin{document}

\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

% Angled line connecting to a straigt line. This is where my problem lies.
\draw[red] (A.140) -- ++(0,1) coordinate(temp) -- (temp -| B.50);
\end{tikzpicture}

% Some examples of what I think would be useful in this case.
% None of these things seem to be supported in TikZ.
\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

\draw[red] (A.140) |- ({{$(\currentcoordinate)+(0,1)$}} -| B.50);
\end{tikzpicture}

\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

\draw[red] (A.140) |- ({+ cs:0,1} -| B.50);
\end{tikzpicture}

\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

\draw[red] (A.140) |- ($(+ cs:0,1) + (2,0)$);
\end{tikzpicture}

\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

\draw[red] (A.140) -- ++(0,1) -- (\currentcoordinate -| B.50);
\end{tikzpicture}

\begin{tikzpicture}
% Some nodes. Precise coordinates are unknown.
\node[draw] at (1,1) (A) {Node};
\node[draw, right of=A, above right=0.5cm] (B) {Other Node};
\draw (B.50) -- ++(0,1);

\draw[red] (A.140) let \p1=(B.50), \p2=+(0,1) in |- (\x1,\y2);
\end{tikzpicture}
\end{document}

Results:

Various relative coordinates

[Tex/LaTex] Tikz: Placing a node relative to the (rectangular) coordinates of another

If you load positioning library, then below right=of will be vertically aligned with a right=of node. However, you can use shift to put a node relative to an existing node. Further, you can also hard code the distances using positioning library.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
  \begin{tikzpicture}
    \node (source) {X};
    \node (destn)  at ([shift={(2,1)}]source) {Y};
  \end{tikzpicture}

  With \verb|positioning| library

  \begin{tikzpicture}
    \node (source) {X};
    \node[below right= of source] (destn)   {Y};
    \node[right= of source] (destnn)   {Y};
  \end{tikzpicture}

  With \verb|positioning| library and hard coded distances

  \begin{tikzpicture}
    \node (source) {X};
    \node[below right= 2cm and 3cm of source] (destn)   {Y};
    \node[right= 3cm of source] (destnn)   {Y};
  \end{tikzpicture}
\end{document}

enter image description here

Best Answer

Related Solutions

tikz-pgf – Optimal Methods for Intersections and Calculations with Relative Coordinates in TikZ

[Tex/LaTex] Tikz: Placing a node relative to the (rectangular) coordinates of another

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