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% This is
% pkshorten.mf
%
% Copyright (C) 1989-92 by Elmar Bartel.
%
% This program 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 1, or (at your option)
% any later version.
%
% This program 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 this program; if not, write to the Free Software
% Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
%
def Perpend(expr d,p,real) =
begingroup
save dd; pair dd;
dd = d/length(d);
(p+100*(dd rotated 90) -- p+100*(dd rotated -90)) shifted (dd*real)
endgroup;
enddef;
def ShortenPath(expr p,real) =
begingroup
save pa,pe; path pa,pe;
pa = Perpend(direction 0 of p,point 0 of p,real);
pe = Perpend(-direction length(p) of p,point length(p) of p,real);
subpath (
xpart(p intersectiontimes pa),
xpart(p intersectiontimes pe)) of p
endgroup
enddef;
def ShortenBegin(expr p,real) =
begingroup
save pa; path pa;
pa = Perpend(direction 0 of p,point 0 of p,real);
subpath (xpart(p intersectiontimes pa),length(p)) of p
endgroup
enddef;
def ShortenEnd(expr p,real) =
begingroup
save pe; path pe;
pe = Perpend(-direction length(p) of p,point length(p) of p,real);
subpath (0, xpart(p intersectiontimes pe)) of p
endgroup
enddef;
def LengthenBegin(expr p,real) =
begingroup
save dd; pair dd;
dd= direction 0 of p; dd:= dd/length(dd);
point 0 of p - real*dd -- p
endgroup
enddef;
def LengthenEnd(expr p,real) =
begingroup
save dd; pair dd;
dd= direction length(p) of p; dd:= dd/length(dd);
p -- point length(p) of p + real*dd
endgroup
enddef;
def Lengthen(expr p,real) =
begingroup
save db; pair db;
save de; pair de;
db= direction 0 of p; db:= db/length(db);
de= direction length(p) of p; de:= de/length(de);
point 0 of p - real*db -- p -- point length(p) of p + real*de
endgroup
enddef;
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