%%%% plyhd_05.ldf
%%%% Created by Laurence D. Finston (LDF) Fri Jan 20 21:09:50 CET 2006

%% * (1) Copyright and License.

%%%% This file is part of GNU 3DLDF, a package for three-dimensional drawing. 
%%%% Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 The Free Software Foundation 

%%%% 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. 
%%%% It is also available from 
%%%% http://www.dante.de/software/ctan/, the Dante www-server  
%%%% and from http://wwwuser.gwdg.de/~lfinsto1, 
%%%% the author's website.  

%%%% Please send bug reports to lfinsto1@gwdg.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 the maintainer of 
%%%% GNU 3DLDF to send 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 The Free Software Foundation, Inc.
%%%% 51 Franklin St, Fifth Floor 
%%%% Boston, MA  02110-1301 
%%%% USA 

%%%% lfinsto1@gwdg.de 
%%%% s246794@stud.uni-goettingen.de 


%% *** (3)  The intersection of a `polyhedron' and a `plane'.  It is a `polygon'.
%%          LDF 2006.01.20.

focus f;
set f with_position (0, 0, -20) with_direction (0, 0, 10) 
       with_distance 20;

picture save_picture;


pickup pencircle scaled .1;

beginfig(1);
polyhedron p;
p := unit_icosahedron scaled 4;
draw p;

rectangle r;
r := unit_rectangle scaled 15 rotated (85, 15);

draw r with_color red;

polygon q;

q := p intersection (plane) r;

draw q with_color blue;

save_picture := current_picture;
endfig with_focus f no_sort; 

beginfig(2); 
output save_picture with_projection parallel_x_z;
endfig;

beginfig(3); 
output save_picture with_projection parallel_x_y;
endfig;

beginfig(4); 
output save_picture with_projection parallel_z_y;
endfig;

verbatim_metapost "end";
end;