Cfrgtkky

I want to draw a conical spring using latex in the 2D space.

I used the following command to draw a cyndrical spring between two nodes a and b:

documentclass[10pt,a4paper]{article}

usepackage[utf8]{inputenc}

usepackage{amsmath}

usepackage{amsfonts}

usepackage{amssymb}

usepackage{graphicx}

usepackage{tikz}

usepackage{pgfplots}

usetikzlibrary{decorations.pathmorphing,patterns}

begin{document}

begin{tikzpicture}

node[circle,fill=blue,inner sep=2.5mm] (a) at (0,1.5) {};

draw[decoration={aspect=0.3, segment length=1.5mm, amplitude=3mm,zigzag},decorate] (0,4) -- (a);

draw[decoration={aspect=0.3, segment length=2mm, amplitude=3mm,zigzag},decorate] (0,-4) -- (a);

draw[decoration={aspect=0.3, segment length=1.8mm, amplitude=3mm,zigzag},decorate] (4,0) -- (a);

draw[decoration={aspect=0.3, segment length=1.8mm, amplitude=3mm,zigzag},decorate] (-4,0) -- (a);

fill [pattern = north east lines] (-1,4) rectangle (1,4.3);

draw[thick] (-1,4) -- (1,4);

end{tikzpicture}

end{document}

but I could not use the zigzag options to draw a conical spring with various diameters.

Can anybody help me?

Thanks in advance.

This is a quickly written code, not a decoration (in the usual sense), so this works only for straight lines. If allows you to draw zigzags of varying amplitude. In this implementation, you can specify the number of zigs, not the segment length.

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

usetikzlibrary{calc,decorations.pathreplacing}

tikzset{

varying zigzag/.style={

decorate,decoration={show path construction,

lineto code={

draw 

(tikzinputsegmentfirst) 

foreach XX in {1,...,vzgigzagsteps}

{ -- 

($($(tikzinputsegmentfirst)!{(2*XX-1)/(2*vzgigzagsteps+2)}!(tikzinputsegmentlast)$)!

{(pgfkeysvalueof{/tikz/vzigzag/left diameter}+(pgfkeysvalueof{/tikz/vzigzag/right

diameter}-pgfkeysvalueof{/tikz/vzigzag/left

diameter})*(2*XX-1)/(2*vzgigzagsteps))*0.5cm}!-90:(tikzinputsegmentlast) $)

--

($($(tikzinputsegmentfirst)!{(2*XX)/(2*vzgigzagsteps+2)}!(tikzinputsegmentlast)$)!

{(pgfkeysvalueof{/tikz/vzigzag/left diameter}+(pgfkeysvalueof{/tikz/vzigzag/right

diameter}-pgfkeysvalueof{/tikz/vzigzag/left

diameter})*(2*XX)/(2*vzgigzagsteps))*0.5cm}!90:(tikzinputsegmentlast) $)

} -- (tikzinputsegmentlast);

}}},

vzigzag/.cd,

left diameter/.initial=1,

right diameter/.initial=0,

steps/.store in=vzgigzagsteps,

steps=10}

begin{document}

begin{tikzpicture}

 node[circle,fill=blue,inner sep=2.5mm] (a) at (0,1.5) {};

 draw[varying zigzag] (0,4) -- (a);

 draw[varying zigzag] (0,-4) -- (a);

 draw[varying zigzag] (4,0) -- (a);

 draw[varying zigzag] (-4,0) -- (a);

begin{scope}[,xshift=9cm,vzigzag/left diameter=0,vzigzag/right diameter=1.5]

 node[circle,fill=blue,inner sep=2.5mm] (a) at (0,1.5) {};

 draw[varying zigzag] (0,4) -- (a);

 draw[varying zigzag] (0,-4) -- (a);

 draw[varying zigzag] (4,0) -- (a);

 draw[varying zigzag] (-4,0) -- (a);

end{scope}

end{tikzpicture}

end{document}