Jtdylktuy

In TikZ, I would like to build a macro drawEdges which for a given list of points produces code that runs through all pairs of two subsequent points, and runs the drawEdge macro for them. For example,

drawEdges{(0, 0), (1, 0), (1, 1), (0, 1)}

should expand to

drawEdge{(0, 0)}{(1, 0)}

drawEdge{(1, 0)}{(1, 1)}

drawEdge{(1, 1)}{(0, 1)}

The purpose is to cut down on the verbosity of repeating the drawEdge macro on every pair. How can this be done?

Bonus points if you can also provide a cyclic variant where the expansion includes the pair involving the last and the first point:

drawEdge{(0, 1)}{(0, 0)}

Edit

In my specific case, the drawEdge macro looks something like this:

newcommand{drawEdge}[2]{

    draw[edgeStyle, line width = 1pt] #1 -- #2;

    draw[line width = 0.33pt, draw=white] #1 -- #2;

}

Here edgeStyle includes a decorator to add a custom-styled arrow tip on a position other than the end, and the latter line hollows out the edge. I would also accept a solution which refactors the process into two separate passes

newcommand{drawEdgeFirst}[2]{

    draw[edgeStyle, line width = 1pt] #1 -- #2;

}



newcommand{drawEdgeSecond}[2]{

    draw[line width = 0.33pt, draw=white] #1 -- #2;

}

with corresponding drawEdgesFirst and drawEdgesSecond. Then we could do

newcommand{drawEdges}[1]{

    drawEdgesFirst{#1}

    drawEdgesSecond{#1}

}

Edit 2

Here's an example of the things I'm drawing. Note that I need exact control of how the hollowing of the edge is done (i.e. its width), so that it connects properly with the arrow tips.

Edit 3

Just realized the hollow edges can be drawn using

newcommand{drawEdge}[2] {

    draw[edgeStyle, line width = 0.335pt, double distance = 0.33pt] #1 -- #2;

}

where the hollowing distance can be controlled precisely.

Here come the requested macros. I added one possible definition for drawEdge, which you can change. EDIT: I corrected the orientation of the last segment. And, more importantly, I also added a way to achieve this with a simple tikz style separate arrows. The basic trick is to use the show path decoration to draw the segments in the way you suggest. You only have to insert you drawEdge macro into the lineto code (and closepath code, and you are done. Then a simple

draw[separate arrows] plot coordinates {(0, 0) (1, 0) (1, 1) (0, 1)} -- cycle;

does the trick.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{decorations.pathreplacing,decorations.markings}

tikzset{separate arrows/.style={%

    decoration={show path construction,

        lineto code={%

            draw [edgeStyle, line width = 0.2] 

            (tikzinputsegmentfirst) -- (tikzinputsegmentlast);

            draw[line width = 0.1, draw=white] 

            (tikzinputsegmentfirst) -- (tikzinputsegmentlast);

        },

        closepath code={%

            draw [edgeStyle, line width = 0.2] 

            (tikzinputsegmentfirst) -- (tikzinputsegmentlast);

            draw[line width = 0.1, draw=white] 

            (tikzinputsegmentfirst) -- (tikzinputsegmentlast);

        },

     },

    postaction=decorate

}}



begin{document}

newcommand{drawEdge}[2]{draw[edgeStyle, line width = 0.2] #1 -- #2;

    draw[line width = 0.1, draw=white] #1 -- #2;}

newcommand{drawEdges}[1]{%

foreach [count=Y] X in {#1}

{xdeftmpLen{Y}

ifnumY=1

xdefmyLst{"X"}

else

xdefmyLst{myLst,"X"}

fi}

xdefmyLst{{myLst}}

foreach X [remember=X as Y (initially 1)] in {2,...,tmpLen}

{pgfmathsetmacro{myfrom}{myLst[Y-1]}

pgfmathsetmacro{myto}{myLst[X-1]}

drawEdge{myfrom}{myto}

}}

newcommand{drawEdgesCyclic}[1]{%

foreach [count=Y] X in {#1}

{xdeftmpLen{Y}

ifnumY=1

xdefmyLst{"X"}

else

xdefmyLst{myLst,"X"}

fi}

xdefmyLst{{myLst}}

foreach X [remember=X as Y (initially 1)] in {2,...,tmpLen}

{pgfmathsetmacro{myfrom}{myLst[Y-1]}

pgfmathsetmacro{myto}{myLst[X-1]}

drawEdge{myfrom}{myto}

}

pgfmathsetmacro{myfrom}{myLst[tmpLen-1]}

pgfmathsetmacro{myto}{myLst[0]}

drawEdge{myfrom}{myto}

}

begin{tikzpicture}[edgeStyle/.style={latex-stealth}]

drawEdges{(0, 0), (1, 0), (1, 1), (0, 1)}

begin{scope}[xshift=2cm,blue]

drawEdgesCyclic{(0, 0), (1, 0), (1, 1), (0, 1)}

end{scope}

begin{scope}[yshift=-2cm]

draw[separate arrows] plot coordinates {(0, 0) (1, 0) (1, 1) (0, 1)};

begin{scope}[xshift=2cm,blue]

draw[separate arrows] plot coordinates {(0, 0) (1, 0) (1, 1) (0, 1)}

-- cycle;

end{scope}

end{scope}

end{tikzpicture}

end{document}

Just for fun: something that approaches your screen shot.

documentclass[tikz,border=3.14mm]{standalone}

usetikzlibrary{decorations.pathreplacing,decorations.markings,calc}

newcommand{drawEdge}[2]{

            draw let p1=($(#1)-(#2)$),

            n1={veclen(x1,y1} in ifdimn1>60pt [edgeStyle={0.3}{-1}, line width = 0.2] 

            (#1) -- (#2)fi;

            draw [edgeStyle={0.7}{1}, line width =2pt] 

            (#1) -- (#2);

            draw[line width = 1, draw=white] 

            (#1) -- (#2);

            draw[fill=white] (#1) circle (1mm);

            draw[fill=white] (#2) circle (1mm);

}

tikzset{separate arrows/.style={%

    decoration={show path construction,

        lineto code={%

            drawEdge{tikzinputsegmentfirst}{tikzinputsegmentlast}

        },

        closepath code={%

            drawEdge{tikzinputsegmentfirst}{tikzinputsegmentlast}

        },

     },

    postaction=decorate

}}



begin{document}



begin{tikzpicture}[edgeStyle/.style n args={2}{-,postaction={decorate,

decoration={markings,mark=at position #1 with {%

fill[black] (#2*0.25,#2*1pt) -- ({#2*(-0.25)},#2*0.15)

--({#2*(-0.25)},#2*1pt);}}}}]

draw[separate arrows,fill=gray!30] plot coordinates {(0, 0) (3, 0) (3, 2) (0, 2)}

-- cycle;

end{tikzpicture}

end{document}

Here is another proposal that uses a foreach loop on all points. Not knowing what your macro is doing, I commented on his call.

Update 4 Cyclic at the request of the OP

documentclass[border=5mm]{standalone}

usepackage{tikz}

usetikzlibrary{arrows.meta}

newcommand{drawEdge}[2]{

    draw[edgeStyle] #1 -- #2;

    draw[line width = 0.1, draw=white] #1 -- #2;

}



newcommand{drawEdges}[1]{

begin{tikzpicture}

tikzset{edgeStyle/.style={blue!75!black,thick,->,>={Straight Barb[angle=50:2pt 3]}}}

foreach point [count=n,remember=point as p (initially point)] in

{(0,0),(1, 0), (1, 1), (0, 1)}

{   node (pointn) at point {};



}

foreach i [remember= i as lasti (initially n)]in {1,...,n}{

drawEdge{(pointlasti.center)}{(pointi.center)}



}

end{tikzpicture}

}

begin{document}

drawEdges{(0,0),(1, 0), (1, 1), (0, 1)}

end{document}

Update 3

Another possibility with the ifthen else test:

documentclass[border=5mm]{standalone}

usepackage{tikz}



newcommand{drawEdge}[2]{

    draw[edgeStyle] #1 -- #2;

    draw[line width = 0.1, draw=white] #1 -- #2;

}



newcommand{drawEdges}[1]{

begin{tikzpicture}

tikzset{edgeStyle/.style={blue,line width = 0.2}}

foreach point [remember=point as p (initially point)] in

{#1}

{ ifthen {p=point} {}

    {drawEdge{p}{point}}

}



end{tikzpicture}

}

begin{document}

begin{tikzpicture}



drawEdges{(0,0),(1, 0), (1, 1), (0, 1)}

end{tikzpicture}

end{document}

Second update (to answer OP's comment)

documentclass[border=5mm]{standalone}

usepackage{tikz}



newcommand{drawEdge}[2]{

    draw[edgeStyle] #1 -- #2;

    draw[line width = 0.1, draw=white] #1 -- #2;

}



newcommand{drawEdges}[1]{

begin{tikzpicture}

tikzset{edgeStyle/.style={blue,line width = 0.2}}

foreach point [remember=point as p (initially point)] in

{#1}

{

    drawEdge{p}{point}

}



end{tikzpicture}

}

begin{document}

begin{tikzpicture}



drawEdges{(0,0),(1, 0), (1, 1), (0, 1)}

end{tikzpicture}

end{document}

Update

I have removed the parentheses around the parameters of your macro DrawEdge since the foreach loop performs an iteration on point coordinates including parentheses.

documentclass[border=5mm]{standalone}

usepackage{tikz}



newcommand{drawEdge}[2]{

    draw[edgeStyle] #1 -- #2;

    draw[line width = 0.1, draw=white] #1 -- #2;

}



begin{document}

begin{tikzpicture}

tikzset{edgeStyle/.style={blue,line width = 0.2}}

foreach point [remember=point as p (initially {(0,0)})] in

{(1, 0), (1, 1), (0, 1)}

{

    drawEdge{p}{point}

%    draw[red] p -- point circle(1mm);

}



begin{scope}[xshift=2cm]

foreach point [remember=point as p (initially {(0,1)})] in

{(0,0),(1, 0), (1, 1), (0, 1)}

{

    drawEdge{p}{point}

%    draw[blue] p -- point circle(1mm);

}

end{scope}

end{tikzpicture}

end{document}

Old answer

documentclass[border=5mm]{standalone}

usepackage{tikz}



begin{document}

begin{tikzpicture}



foreach point [remember=point as p (initially {(0,0)})] in

{(1, 0), (1, 1), (0, 1)}

{

    %\drawEdge{p}{point}

    draw[red] p -- point circle(1mm);

}



begin{scope}[xshift=2cm]

foreach point [remember=point as p (initially {(0,1)})] in

{(0,0),(1, 0), (1, 1), (0, 1)}

{

    %\drawEdge{p}{point}

    draw[blue] p -- point circle(1mm);

}

end{scope}

end{tikzpicture}

end{document}

If drawEdge draws lines, then one can use plot coordinates{<coordinates>} to achieve this.

A MWE:

documentclass[tikz,border=3mm]{standalone}

usetikzlibrary{calc}

begin{document}

begin{tikzpicture}

draw[smooth cycle,tension=0] plot coordinates{(0,0) (0,1) (1,1) (1,0)};

draw[red] plot coordinates{(0,2) (0,3) (1,3) (1,2)};

end{tikzpicture}

end{document}