input fks
verbatimtex
%&latex
\documentclass[9pt]{extarticle}
\usepackage[utf8]{inputenc}
\usepackage{fkssugar}
\begin{document}
etex
 
prologues:=3;

 
beginfig(1);
u:=.3cm;

def spojka(expr A,B)=
   alphamo := 30;
   delkasipky := .07;
   path delka;
   delka := A--B;
   sipka := sqrt((ypart(A-B)**2)+(xpart(A-B)**2))*delkasipky; %vzdalenost bodu A a B
   draw delka;
   draw A--A+sipka*dir (angle(A-B)+180-alphamo);
   draw A--A+sipka*dir (angle(A-B)+180+alphamo);
   draw B--B+sipka*dir (angle(B-A)+180-alphamo);
   draw B--B+sipka*dir (angle(B-A)+180+alphamo);
enddef;

spojka((0,8u),(0,-8u));
draw (-2u,2u)--(-6u,2u)--(-6u,-2u)--(-2u,-2u)--cycle;
draw (-10u, 0)--(20u,0) withpen pencircle scaled .1bp;

carka:=.2u;
draw (-4u,carka)--(-4u,-carka);
draw (4u,carka)--(4u,-carka);
endfig;
verbatimtex
\end{document}
etex
 
end;