%%%% intrfr_2.ldf
%%%% Created by Laurence D. Finston (LDF) Sun Aug 10 18:39:19 CEST 2008

%% $Id: intrfr_2.ldf,v 1.13 2025/01/01 11:42:32 lfinsto1 Exp $

%% * (1) Copyright and License.

%%%% This file is part of GNU 3DLDF, a package for three-dimensional drawing.  
%%%% Copyright (C) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 The Free Software Foundation, Inc.  

%%%% GNU 3DLDF is free software; you can redistribute it and/or modify 
%%%% it under the terms of the GNU General Public License as published by 
%%%% the Free Software Foundation; either version 3 of the License, or 
%%%% (at your option) any later version.  

%%%% GNU 3DLDF is distributed in the hope that it will be useful, 
%%%% but WITHOUT ANY WARRANTY; without even the implied warranty of 
%%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
%%%% GNU General Public License for more details.  

%%%% You should have received a copy of the GNU General Public License 
%%%% along with GNU 3DLDF; if not, write to the Free Software 
%%%% Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA 

%%%% GNU 3DLDF is a GNU package.  
%%%% It is part of the GNU Project of the  
%%%% Free Software Foundation 
%%%% and is published under the GNU General Public License. 
%%%% See the website http://www.gnu.org 
%%%% for more information.   
%%%% GNU 3DLDF is available for downloading from 
%%%% http://www.gnu.org/software/3dldf/LDF.html.

%%%% Please send bug reports to Laurence.Finston@gmx.de
%%%% The mailing list help-3dldf@gnu.org is available for people to 
%%%% ask other users for help.  
%%%% The mailing list info-3dldf@gnu.org is for sending 
%%%% announcements to users. To subscribe to these mailing lists, send an 
%%%% email with ``subscribe <email-address>'' as the subject.  

%%%% The author can be contacted at: 

%%%% Laurence D. Finston 
%%%% c/o Free Software Foundation, Inc. 
%%%% 51 Franklin St, Fifth Floor 
%%%% Boston, MA  02110-1301  
%%%% USA

%%%% Laurence.Finston@gmx.de
 


%% Last updated:  August 11, 2008

%% Run like this:

%% 3dldf intrfr_2.ldf 
%% mpost intrfr_2.mp 
%% tex intrfr_2.txt 
%% dvips -o intrfr_2.ps intrfr_2.dvi

%% All on one line:
if false:
3dldf intrfr_2.ldf; mpost intrfr_2.mp; tex intrfr_2.txt; \
dvips -o intrfr_2.ps intrfr_2.dvi
fi;

%% View using Ghostview like this:
%% gv intrfr_2.ps &

%% Generate animated GIF like this:
%% conveps --end=71 --output-format=jpeg --start=0 --border=0 intrfr_2
%% convert -delay 25 intrfr_2_*.jpg intrfr_2.gif
%%
%% Other formats can be used;  it doesn't have to be JPEG.

%% The animated GIF can be viewed using the `animate' program from ImageMagick:
%% animate intrfr_2.gif 

%% * (1) Beginning of 3DLDF code.

%% ** (2) Interference Patterns 2
%%        LDF 2008.08.11.


circle c[];

%point p[];
path q;

pickup pencircle scaled (1.0mm, 1.0mm);

m := 10;
n := 10;

q := (-m, -n) -- (m, -n) -- (m, n) -- (-m, n) -- cycle;

k := 256;


for i = 0 upto 71:
   beginfig(i); 
      draw q;
      for j = .5 step 1 until 15.5:

         set c0 with_diameter j with_point_count k;
         c1 := c0;

         rotate c0(i * 5, 0, 0);
         shift c0 by (0, .5);

         rotate c1(-i * 5, 0, 0);
         shift c1 by (0, -.5);

         %p0 := get_point 192 c0;
         %p1 := get_point 192 c1;

         %message "p0:"; 
         %show p0;
         %message "p1:"; 
         %show p1;

         draw c0 with_color red;
         draw c1 with_color blue;

         %drawdot p0 with_pen pencircle scaled (2mm, 2mm) with_color red;
         %drawdot p1 with_pen pencircle scaled (2mm, 2mm) with_color red;
      endfor;

   endfig with_projection parallel_x_y no_sort;
endfor;

%% *** (3) End of 3DLDF code

verbatim_metapost "end;";

end;

%% ** (2) 

%% * (1) Emacs-Lisp code for use in indirect buffers when using the          
%%   	 GNU Emacs editor.  The local variable list is not evaluated when an 
%%   	 indirect buffer is visited, so it's necessary to evaluate the       
%%   	 following s-expression in order to use the facilities normally      
%%   	 accessed via the local variables list.                              
%%   	 \initials{LDF 2004.02.12}.                                          

%% (progn (metafont-mode) (outline-minor-mode t) (setq fill-column 80) (ignore '(  
%% )) (setq outline-regexp "%% [*\f]+"))

%% * (1) Local variables for Emacs.

%% Local Variables:
%% mode:Metafont
%% eval:(outline-minor-mode t)
%% eval:(read-abbrev-file abbrev-file-name)
%% outline-regexp:"%% [*\f]+"
%% End: