/drawarc {
	% unit-label, x1, l1, x2, l2, ... xn, ln, n (number of edges)

dup 2 mul 1 add copy	% x1, l1, x2, l2, ... xn, ln, n, x1, l1, x2, l2, ... xn, ln, n

0 exch			% x1, l1, x2, l2, ... xn, ln, n, x1, l1, x2, l2, ... xn, ln, 0, n
{exch pop add} repeat	% x1, l1, x2, l2, ... xn, ln, n, total

dup 2 div dup 90 exch sub exch 90 add % x1, l1, x2, l2, ... xn, ln, n, total a1 a2 

currentpoint 4 copy	% x1, l1, x2, l2, ... xn, ln, n, total a1 a2 x y a1 a2 x y

newpath			% this keeps a straight line from being prepended to the arc
r1 5 -2 roll            % x1, l1, x2, l2, ... xn, ln, n, total a1 a2 x y x y r1 a1 a2
exch arcn 4 copy              % x1, l1, x2, l2, ... xn, ln, n, total a1 a2 x y a1 a2 x y 
r2 5 -2 roll            % x1, l1, x2, l2, ... xn, ln, n, total a1 a2 x y x y r2 a1 a2
arc                     % x1, l1, x2, l2, ... xn, ln, n, total a1 a2 x y
3 -1 roll pop		% x1, l1, x2, l2, ... xn, ln, n, total a1 x y
4 -1 roll pop		% x1, l1, x2, l2, ... xn, ln, n, a1 x y
4 -1 roll		% x1, l1, x2, l2, ... xn, ln, a1 x y n
{ 
  5 copy		% x1, l1, x2, l2, ... xn ln a1 x y  xn ln a1 x y
  5 -1 roll 2 div	% x1, l1, x2, l2, ... xn ln a1 x y  ln a1 x y xn/2
  4 -1 roll add 	% x1, l1, x2, l2, ... xn ln a1 x y  ln x y t
  dup sin r3 mul exch cos r3 mul	% x1, l1, x2, l2, ... xn ln a1 x y  ln x y r*sin(t) r*cos(t)
  4 -1 roll add 3 1 roll add moveto cshow

  4 -1 roll pop		% x1, l1, x2, l2, ... xn a1 x y
  4 2 roll add		% x1, l1, x2, l2, ... x y t
  3 copy		% x1, l1, x2, l2, ... x y t x y t
  dup sin exch cos	% x1, l1, x2, l2, ... x y t x y sin(t) cos(t)
  4 copy		% x1, l1, x2, l2, ... x y t x y sin(t) cos(t) x y sin(t) cos(t)
  r1 mul 4 -1 roll add	% x1, l1, x2, l2, ... x y t x y sin(t) cos(t) y sin(t) cos(t)*r1+x
  3 1 roll r1 mul add moveto	% x1, l1, x2, l2, ... x y t x y sin(t) cos(t)
  r2 mul 4 -1 roll add
  3 1 roll r2 mul add lineto	% x1, l1, x2, l2, ... x y t
  3 1 roll 
} repeat		% unit-label t x y
3 2 roll 3 add dup cos r3 mul exch sin r3 mul	% unit-label x y cos(t) sin(t)
4 copy pop pop
4 -1 roll 3 -1 roll add 3 1 roll add moveto	% unit-label x y
3 -1 roll cshow
stroke
moveto
} def

/cshow {
  gsave
  0.1 setlinewidth
  currentpoint 2 copy  % a x y x y
  newpath
  2 copy exch r4 add exch moveto r4 0 360 arc
  3 copy pop pop	% a x y a
  stringwidth pop
  -2 div 3 -1 roll add exch -0.5 r4 mul add moveto
  show
  closepath stroke
  grestore
} def