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Sample Programs from NeXSTEP 3.3

%!PS-Adobe-2.0 EPSF-2.0
%%Title: arrows.eps
%%Creator: Adobe Systems Incorporated
%%Pages: 0 1 
%%BoundingBox: 0 0 300 540
%%EndComments
%%BeginProcSet: arrows 1.0 0
% From: Green Book Listing 3-4, on page 47.

% "arrowhead" takes these arguments:
% lineweight prevX prevY
 /arrowhead { %def
	gsave
		currentpoint
		4 2 roll exch 4 -1 roll exch
		sub 3 1 roll sub
		exch atan rotate dup scale
		-1 2 rlineto
		7 -2 rlineto
		-7 -2 rlineto
		closepath fill
	grestore
	newpath
 } bind def
 /l^ { %def    % lineto-arrow
	currentlinewidth currentpoint 5 3 roll
	lineto
	currentpoint stroke moveto
	arrowhead
 } bind def
 /rl^ { %def    % rlineto-arrow
	currentlinewidth currentpoint 5 3 roll
	rlineto
	currentpoint stroke moveto
	arrowhead
 } bind def
 /arc^ { %def    % arc-arrow
	5 copy arc
	currentpoint stroke moveto           % stroke arc
  % getting the correct orientation for the arrowhead
  % is tricky. This procedure uses the arguments to
  % "arc" to determine the tangent of the curve at the
  % endpoint, and it orients the arrowhead along that
  % tangent line.  It leaves an X-Y point that is just
  % behind the arrowhead along the tangent.
  % newX = X + radius * cos(endAngle-1)
  % newY = Y + radius * sin(endAngle-1)
	exch pop 1 sub   % endAngle - 1 degree
	dup cos 2 index mul 4 index add     % arrowX
	exch sin 2 index mul 3 index add    % arrowY
	currentlinewidth 2 add 3 1 roll      % thickness
	arrowhead pop pop pop                  % draw -\>
 } bind def
%%EndProcSet: arrows 1.0 0
%%EndProlog
 % line sample:
 150 420 moveto
 0 10 360 {
	currentlinewidth .1 add setlinewidth
	gsave
	dup cos 100 mul
	exch sin 100 mul
	rl^
	grestore
 } bind for
 newpath
 % curve sample:
 /radius 10 def .1 setlinewidth
 0 30 360 {
	/radius radius 10 add def
	150 150 radius 0 5 -1 roll arc^
 } bind for
 showpage
%%Trailer

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