PSTricks drawing with variables not exact

Question

Consider the following example:

\documentclass{article}

\usepackage{pst-coil}

\psset{dimen = middel}

\def\frekvensgenerator[#1,#2](#3,#4){
  \psframe(#3,#4)(!#3 #1 add #4 #2 add)
  \psline(!#3 #4 #2 2 div add)(!#3 #1 add #4 #2 2 div add)
  \psframe(!#3 #1 2 div add 0.2 sub #4)(!#3 #1 2 div add 0.2 add #4 #2 2 div add)
  \rput{270}(!#3 #1 2 div add #4){%
    \psCoil[
      linewidth = 1.5pt,
      coilwidth = \spolevidde,
      coilheight = \spolehoejde,
      coilarm = 0
    ]{0}{\drejning}%
  }
  \psframe[
    fillstyle = solid,
    fillcolor = yellow!70
  ](!#3 #1 2 div add 0.25 sub  #4 \drejning\space 480 div \spolevidde\space mul \spolehoejde\space mul sub 1 sub)(!#3 #1 2 div add 0.25 add  #4 \drejning\space 480 div \spolevidde\space mul \spolehoejde\space mul sub)
  \psline(!#3 #1 2 div add #4 \drejning\space 480 div \spolevidde\space mul \spolehoejde\space mul sub 1 sub)(!#3 #1 2 div add #4 \drejning\space 480 div \spolevidde\space mul \spolehoejde\space mul sub 3 sub)
}

\begin{document}

\def\spolevidde{0.5}
\def\spolehoejde{0.5}

\begin{pspicture}(3.5,6.2)
\def\drejning{810}
  \frekvensgenerator[1.5,1.5](0,4.7)
\def\drejning{3330}
  \frekvensgenerator[1.5,1.5](2,4.7)
\end{pspicture}

\end{document}

output

As can be seen, the weight is not connected to the same point on the spring (modulo an integer number of windings) if I change the total numbers of degrees that the spring is twisted.

How do I accomplish this?

P.S. If the code can be made simpler (which it almost certainly can), you are very welcome to improve it. :)

As your question is not minimal, I also provide you with the same complex answer. My answer here has been made to answer your question. — kiss my armpit, Dec 28 '13 at 10:13
@StiffJokes Looks nice. Can I make you give an answer to this specific question none the less? :) (Code improvement is more than welcome.) — Svend Tveskæg, Dec 28 '13 at 10:22
The coil projection should be seen as a zigzag line rather than a coil. — kiss my armpit, Dec 28 '13 at 13:23

score 8 · Accepted Answer · 2013-12-28T17:03:31.517

\documentclass{article}
\usepackage{pst-coil}
%\psset{dimen = middel}

\def\frekvensgenerator[#1,#2](#3,#4)#5{%
  \psframe(#3,#4)(!#3 #1 add #4 #2 add)
  \psline(!#3 #4 #2 2 div add)(!#3 #1 add #4 #2 2 div add)
  \psframe(!#3 #1 2 div add 0.2 sub #4)(!#3 #1 2 div add 0.2 add #4 #2 2 div add)
  \rput{270}(!#3 #1 2 div add #4){%
    \psCoil[
      linewidth = 1.5pt,
      coilwidth = \spolevidde,
      coilheight = \spolehoejde,
      coilaspect=45,
    ]{0}{#5}%
  }%
  \psframe[fillstyle = solid,fillcolor = yellow!70]%
    (!#3 #1 2 div add 0.25 sub #4 #5 360 div \dxCoil mul sub 1 sub)%
    (!#3 #1 2 div add 0.25 add #4 #5 360 div \dxCoil mul sub  )
  \psline(!#3 #1 2 div add #4 #5 360 div \dxCoil mul sub 1 sub)%
    (!#3 #1 2 div add #4 #5 360 div \dxCoil mul sub 3 sub)%
}

\begin{document}
\def\spolevidde{0.5 }
\def\spolehoejde{0.5 }
\edef\dxCoil{ \spolehoejde \spolevidde mul 45 sin mul }

\begin{pspicture}(3.5,6.2)
  \frekvensgenerator[1.5,1.5](0,4.7){810}
  \frekvensgenerator[1.5,1.5](2,4.7){3330}
  \frekvensgenerator[1.5,1.5](4,4.7){6930}
\end{pspicture}

\end{document}

enter image description here

45 sin is needed for the 3d view. The coil is seen under an angle of 45, which is the value of coilaspect, which is by default 45. However, I suppose you are looking for something like this:

\documentclass{article}
\usepackage{pst-coil}

\makeatletter
\def\frekvensgenerator{\@ifnextchar[\frekvensgenerator@i{\frekvensgenerator[1.5,1.5]}}
\def\frekvensgenerator@i[#1,#2](#3,#4)#5{%
  \psframe(#3,#4)(!#3 #1 add #4 #2 add)
  \psline(!#3 #4 #2 2 div add)(!#3 #1 add #4 #2 2 div add)
  \psframe(!#3 #1 2 div add 0.2 sub #4)(!#3 #1 2 div add 0.2 add #4 #2 2 div add)
  \pnode(!#3 #1 2 div add #4){StartX}
  \psline[linewidth=1.5pt](StartX)(StartX|{!0 #4 \spolearm sub})
  \rput{270}(StartX|{!0 #4 \spolearm sub \dxCoil 2 div sub}){%
    \psCoil[
      linewidth = 1.5pt,
      coilwidth = \spolevidde,
      coilheight = \spolehoejde,
    ]{-90}{#5}%
  }%
  \psline[linewidth = 1.5pt]%
    (StartX|{!0 #4 #5 90 sub 360 div \dxCoilRel mul sub \spolearm sub \dxCoil sub})%
    (StartX|{!0 #4 #5 90 sub 360 div \dxCoilRel mul sub \spolearm dup add sub \dxCoil sub})
  \psframe[fillstyle = solid,fillcolor = yellow!70]%
    (!#3 #1 2 div add 0.25 sub #4 
      #5 90 sub 360 div \dxCoilRel mul sub \spolearm dup add sub \dxCoil sub)%
    (!#3 #1 2 div add 0.25 add #4 
      #5 90 sub 360 div \dxCoilRel mul sub \spolearm dup add sub \dxCoil sub 1 sub)
  \pnode(StartX|{!0 #4 #5 90 sub 360 div \dxCoilRel mul sub 
                  \spolearm dup add sub \dxCoil sub 3 sub}){End#3}
  \psline(StartX|{!0 #4 #5 90 sub 360 div \dxCoilRel mul sub 
                   \spolearm dup add sub \dxCoil sub 1 sub})(End#3)%
}
\makeatother
\begin{document}
\def\spolearm{0.2 }
\def\spolevidde{0.5 }
\def\spolehoejde{0.3 }
\def\dxCoil{ \spolehoejde \spolevidde mul }
\def\dxCoilRel{ \dxCoil 45 sin mul }

\begin{pspicture}(3.5,6.2)
  \frekvensgenerator(0,4.7){3690}
  \def\spolevidde{0.45 }\def\spolehoejde{0.6 }
  \frekvensgenerator(2,4.7){3690}
  \def\spolevidde{0.4 }\def\spolehoejde{1.2 }
  \frekvensgenerator(4,4.7){3690}
  \def\spolevidde{0.35 }\def\spolehoejde{2.4 }
  \frekvensgenerator(6,4.7){3690}
  \pscurve[linecolor=red,linewidth=1.5pt](End0)(End2)(End4)(End6)
\end{pspicture}

\end{document}

enter image description here

and as animation:

enter image description here

kiss my armpit · Answer 2 · 2013-12-28T21:40:12.573

pszigzag provided by pst-coil does not seem to be reliable so I create my own zigzag as follows.

Make sure \CoilWidth never becomes negative in all frames when creating animations.

\FPeval\CoilWidth{1-1.4*Lambda}% make sure it never becomes negative, otherwise the orientation will change!

MWE

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{pst-node,pst-plot}
\usepackage[nomessages]{fp}

\FPset\CoilArm{.6}
\FPset\Windings{7}

\psset
{
    dimen=medusa,
    fillcolor=yellow,
    linejoin=1,
}

\def\System#1{% #1: total length includes the arms
    \FPeval\Lambda{(#1-2*CoilArm)/Windings}%
    \FPeval\CoilWidth{1-1.4*Lambda}% make sure it never becomes negative, otherwise the orientation will change!
    \FPeval\PlotPoints{trunc(4*Windings+1,0)}%
    \curvepnodes[plotpoints=\PlotPoints,algebraic]{0}{\Lambda\space \Windings\space mul}{\CoilWidth*sin(2*Pi*t/\Lambda)|-t-\CoilArm}{P}%
    \rput(-.5,0){\psframe(1,1)\psframe(1,.5)\psframe(!1 3 div 0)(!2 3 div .5)}%
    \pscustom
    {
        \psline(0,0)
        \psnline(0,\Pnodecount){P}
        \psline(0,-#1)
    }%
    \rput(!-.25 -#1 1 sub){\psframe[fillstyle=solid](.5,1)\psline(.25,0)(.25,-2)}%
    \ignorespaces
}

\def\func(#1){2*sin(2*pi*#1/1)+4}

\begin{document}
\multido{\n=.00+.05}{21}{%
\begin{pspicture}(1,-9)(3,1)
    \rput(2,0){\FPeval\y{\func(\n)}\System{\y}}
\end{pspicture}}
\end{document}

enter image description here

PSTricks drawing with variables not exact

2 Answers2

MWE