rosette.ps

%!
%%BoundingBox: 124.38 124.38 487.61 487.61
% Cookbook Example Program from First Printing, Revised 7 Jan 1985
% Program: Repeated Shapes     Number: 6
%-----------------------------------------------------------------------------
%
					    % This program prints a rosette
					    % design by defining a section of
					    % that design and printing that
					    % section repeatedly. This program
					    % illustrates the ``for'' and
					    % "arc" operators, and it shows
					    % how coordinate transformations
					    % can be nested so as to use the
					    % most convenient coordinate
					    % system for each part of a
					    % design.
/inch {72 mul} def
		  
/wedge                                      % Define an ``ice cream cone''
  { newpath                                 % shape by means of the ``arc''
      0 0 moveto                            % operator. This shape will have a
      1 0 translate                         % 30 degree angle topped off with
      15 rotate                             % a semicircle. Set the path's
      0 15 sin translate                    % first point at the current
      0 0 15 sin -90 90 arc                 % origin. Next, move the origin to
    closepath                               % the center of the semicircle by
  } def                                     % translating to the right 1 unit,
					    % rotating counter-clockwise by 15
					    % degrees, and translating ``up''
					    % in the rotated system by the
					    % radius of the semicircle. The
					    % ``arc'' operator includes a
					    % straight line to the initial
					    % point of the arc and a curved
					    % section to the end of the arc.
					    % Note that the semicircle goes
					    % from -90 degrees to 90 degrees
					    % in the rotated coordinate
					    % system.
						     
gsave
  4.25 inch 4.25 inch translate             % Move into position for the
					    % rosette.
  1.75 inch 1.75 inch scale                 % Make the edges of the rosette 1
					    % 3/4 inches long.
  0.02 setlinewidth                         % Use a 7/200 inch thick line.
  2 1 13                                    % Set up the ``for'' operator to
					    % iterate 12 times, pushing 2 onto
					    % the stack the first time, 3 the
					    % next time, ... , and 13 the last
					    % time.
   {                                        % The last argument for ``for'' is
					    % the sequence of operations to be
					    % repeated. This sequence must be
					    % enclosed by braces.
     13 div setgray                         % Divide the loop index by 13 to
					    % set a gray value.
     gsave                                  % Enclose the ``wedge'' operation
       wedge                                % in a ``gsave''-``grestore''
					    % pair, as it will mess up the
					    % coordinate system.
       gsave                                % Save the wedge path for use
					    % after the ``fill''.
	 fill
       grestore
       0 setgray stroke                     % Draw a black border around the
					    % wedge.
     grestore                               % Get out of the coordinate system
					    % left by wedge.
     30 rotate                              % Set up for the next section.
   } for                                    % Close the last argument and
					    % execute the ``for'' operator.
grestore
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