%!PS-Adobe
% universal constants
/mm { 72 mul 25.4 div } bind def
/pi 3.14159 def
/radians { 180 mul pi div } bind def
/awl { currentpoint gsave newpath 1.5 0 360 arc fill grestore } def
/mark { currentpoint gsave newpath 5 0 360 arc stroke grestore } def

% begin configuration
/D 65 mm def
/theta 0.3039 def
% by experiment, theta=0.35458 gave an eggness of 1.156
% theta=0.3039 seems to equalise the two orthogonal circumferences
/clearance   2.5 mm def
/holespacing 4.0 mm def
% end configuration

% derived stuff, see www.pjb.com.au/jug/two_peice_balls.html
% /D D 0.97 mul def   % fudge factor to compensate for stretching
/r_over_d 0.5 0.25 pi mul theta div add def
/cos_theta theta radians cos def
/alpha cos_theta 2.0 r_over_d mul 1.0 cos_theta sub mul sub def
/d D pi mul 4.0 div cos_theta div def
/r d r_over_d mul def
/d_over_2 d 0.5 mul def
/l r theta radians sin mul 2.0 mul d theta radians sin mul add def
/n d pi 0.5 mul theta add mul holespacing div round def % num of points per arc
/d_theta pi theta add theta add n div radians def
/d_phi theta 2.0 mul  n div radians def

% display and layout stuff
/dx d 1.2 mul def
/xinst 70 mm def
/yinst 15 mm def
/stagger 0.05 def

/strip {
	% scissor lines
	newpath l 0.5 mul 0 d_over_2 clearance add
	 270 theta radians sub 90 theta radians add arc stroke
	newpath 0 r d_over_2 add cos_theta mul  r clearance sub
	 270 theta radians sub 270 theta radians add arc stroke
	newpath l -0.5 mul 0 d_over_2 clearance add
	 90 theta radians sub 270 theta radians add arc stroke
	newpath 0 r d_over_2 add cos_theta mul -1 mul  r clearance sub
	 90 theta radians sub 90 theta radians add arc stroke

	% awl dots along the sides
	gsave 0 r d_over_2 add cos_theta mul translate
	/t d_phi theta radians sub def
	/i 2 def {
		r t sin mul  r t cos mul -1 mul moveto awl
		i n ge { exit } if
		/t t d_phi add def
		/i i 1 add def
	} loop
	grestore
	gsave 0 r d_over_2 add cos_theta mul -1 mul translate
	/t d_phi theta radians sub def
	/i 2 def {
		r t sin mul r t cos mul moveto awl
		i n ge { exit } if
		/t t d_phi add def
		/i i 1 add def
	} loop
	grestore

	% awl dots round the semicircles
	gsave l 0.5 mul 0 translate
	/t d_theta theta radians sub def
	/i 2 def {
		d_over_2 t sin mul  d_over_2 t cos mul  moveto awl
		i n ge { exit } if
		/t t d_theta add def
		/i i 1 add def
	} loop
	% awl dots and marks at the joins
	d_over_2 theta radians sin mul -1.0 mul
	 d_over_2 theta radians cos mul moveto mark awl
	d_over_2 theta radians sin mul -1.0 mul
	 d_over_2 theta radians cos mul -1.0 mul moveto mark awl
	grestore
	gsave l -0.5 mul 0 translate
	/t d_theta theta radians sub def
	/i 2 def {
		d_over_2 t sin mul -1 mul d_over_2 t cos mul moveto awl
		i n ge { exit } if
		/t t d_theta add def
		/i i 1 add def
	} loop
	% awl dots and marks at the joins
	d_over_2 theta radians sin mul
	 d_over_2 theta radians cos mul moveto mark awl
	d_over_2 theta radians sin mul
	 d_over_2 theta radians cos mul -1.0 mul moveto mark awl
	grestore

} bind def

% print instructions ...
/Times-Roman findfont 10 scalefont setfont
xinst yinst 12 mm add moveto (Two_piece juggling ball) show
xinst yinst  6 mm add moveto (approx 65mm diam, 115 grams) show
xinst yinst           moveto (see http://www.pjb.com.au/jug) show

105 mm dx stagger mul 0.5 mul sub dx translate strip
dx stagger mul dx translate strip
dx stagger mul -1.0 mul dx translate strip
dx stagger mul dx translate strip
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