Ttdfjt

I would like to create a gif (as explained in this answer) of a point moving along a crooked "multi-node path". I would like this path to be specified as below: a sequence of nodes connected by edges. In the iteration I would like to specify nodes along this "multi-node path" as in node[pos=n, above] x.

I have a solution but it's not easily scalable: if I want more nodes along the path I have to change it by hand. Also there is a problem with the window shifting up and down as the point moves along the path.

I could do this by having as many for loops as there are edges, and placing the node[pos=n, above] x on the relevant edge every time, but I'd like to have a more generic solution where I don't have to know in advance how long the "multi-node path" will be, something like the following (which doesn't work):

documentclass[tikz]standalone
usepackagetikz
usetikzlibraryintersections
begindocument

foreach n in 0,0.05,...,1 
begintikzpicture
draw[name path=mypath]
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
draw (mypath) node [draw=black, fill=red, circle] 
 node [pos=n, above] x;
endtikzpicture


enddocument

My current solution is ugly :( :

documentclass[tikz, border=.5cm]standalone
usepackagetikz
begindocument

foreach n in 0,0.1,...,.9 
begintikzpicture
 draw
 (0,0) -- node [circle, fill=red, draw=black, pos=n, inner sep = 0, minimum size = 4pt] node [pos=n, above] x ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
endtikzpicture


foreach n in 0,0.1,...,.9 
begintikzpicture
 draw
 (0,0) -- ++ (1,2)
 -- node [circle, fill=red, draw=black, pos=n, inner sep = 0, minimum size = 4pt] node [pos=n, above] x ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
endtikzpicture


foreach n in 0,0.1,...,.9 
begintikzpicture
 draw
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- node [circle, fill=red, draw=black, pos=n, inner sep = 0, minimum size = 4pt] node [pos=n, above] x ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
endtikzpicture


foreach n in 0,0.1,...,.9 
begintikzpicture
 draw
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- node [circle, fill=red, draw=black, pos=n, inner sep = 0, minimum size = 4pt] node [pos=n, above] x ++ (1,0)
 -- ++ (1,-4);
endtikzpicture


foreach n in 0,0.1,...,.9 
begintikzpicture
 draw
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- node [circle, fill=red, draw=black, pos=n, inner sep = 0, minimum size = 4pt] node [pos=n, above] x ++ (1,-4);
endtikzpicture


begintikzpicture
 draw
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- node [circle, fill=red, draw=black, pos=1, inner sep = 0, minimum size = 4pt] node [pos=1, above] x ++ (1,-4);
endtikzpicture

enddocument

Use decorations.markings and the overlay option. The overlay option pretends that the object has zero size and therefore doesn't add to the bounding box. Because the nodes are now going outside the bounding box of the path, you have to add a border around the drawing so it doesn't fall off the page.

documentclass[tikz,border=10pt]standalone
usepackagetikz
usetikzlibrarydecorations.markings
begindocument

foreach n in 0,0.05,...,1 
 begintikzpicture
 draw
 [postaction=decorate,
 decoration=
 markings,
 mark=at position n with 
 draw [overlay, draw=black, fill=red] circle (2pt);
 node [overlay, above] x;
 
 ]
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
 endtikzpicture


enddocument

Very similar to Henri Menke's great answer with a small tilt: the bounding box gets recorded and the maximal bounding box of all iterations gets applied. You need to compile twice that it works. The code is more complex but the bounding box gets only increased in the directions in which it is needed. This code is somewhat similar to this nice answer which addresses a similar problem.

documentclass[tikz]standalone
usetikzlibrarydecorations.markings,calc
begindocument
pgfmathsetmacroxmin0
pgfmathsetmacroxmax0
pgfmathsetmacroymin0
pgfmathsetmacroymax0
foreach X in 0,0.05,...,1 
 begintikzpicture
 ifdefinedfigbbrelax
 path figbb;
 fi
 draw
 [postaction=decorate,
 decoration=
 markings,
 mark=at position X with 
 node [circle,inner sep=2pt,draw,fill=red,label=above:$x$];
 
 ]
 (0,0) -- ++ (1,2)
 -- ++ (1,.5)
 -- ++ (1,-1)
 -- ++ (1,0)
 -- ++ (1,-4);
 path let p1=(current bounding box.south west),
 p2=(current bounding box.north east)
 in pgfextra%
 pgfmathsetmacroxminmin(x1,xmin)
 pgfmathsetmacroxmaxmax(x2,xmax)
 pgfmathsetmacroyminmin(y1,ymin)
 pgfmathsetmacroymaxmax(y2,ymax)
 xdefxminxmin pt
 xdefxmaxxmax pt 
 xdefyminymin pt
 xdefymaxymax pt 
 ;
 endtikzpicture

makeatletter 
edeffigbb(xmin,ymin) rectangle (xmax,ymax)
immediatewrite@mainauxxdefstringfigbbfigbbrelax
makeatother
enddocument