%!PS
% Joseph O'Rourke
% Random bow ties
% Uses random numbers a bit...

2 setlinewidth

% NB: I convert-to-integer with cvi because later I want to use mod
/w 8.5 72 mul cvi def
/h 11 72 mul cvi def

% This procedure draws a horizontal bowtie about (x,y).
% How to call: r g b x y length (x,y are center coordinates, length is end-to-end longer dimension in pts)
/bowtie {
   5 dict begin % 5 local vars
   /length exch def
   % Now x and y are on top of the stack
   gsave
      translate % origin now changed, x,y gone from stack
      /b exch def
      /g exch def
      /r exch def
      
      /x length 2 div def
      r g b x triangle
      % Now draw reflected triangle
      gsave
         -1 1 scale
	 r g b x triangle
      grestore
      newpath
      x 3 div 0 moveto
      0 0 x 3 div 0 360 arc
      gsave
      % Fill with complementary color
      1 r sub 1 g sub 1 b sub setrgbcolor
      fill
      grestore
      0 setgray
      stroke
   grestore
   end % dict
} def

% Draw one triangle
% How to call: r g b xlength
/triangle {
    1 dict begin
    /x exch def
    newpath
    x x 2 div moveto
    0 0 lineto
    x x 2 div neg lineto
    closepath
    gsave
    % note: r g b on top of stack
    setrgbcolor
    fill
    grestore
    0 setgray
    stroke
    end % dict
} def


% Draw randomly placed bowties
/n 100 def
% start incr stop
1 1 n {
    /x rand w mod def
    /y rand h mod def
    1 0 0 x y 100 bowtie
} for



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