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% Copyright (C) 1991 Silvio Levy
%
% This file 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 2 of the License, or
% (at your option) any later version.
%
% This file 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, see <http://www.gnu.org/licenses/>.
%
% As a special exception, if you create a document which uses this font,
% and embed this font or unaltered portions of this font into the
% document, this font does not by itself cause the resulting document to
% be covered by the GNU General Public License. This exception does not
% however invalidate any other reasons why the document might be covered
% by the GNU General Public License. If you modify this font, you may
% extend this exception to your version of the font, but you are not
% obligated to do so. If you do not wish to do so, delete this exception
% statement from your version.
if unknown gen_sigma: readfrom("gen_sigma") fi
def dims = 8.5u#,asc_height#,0 enddef;
def ital = 0 enddef;
def fit_params = 0,0 enddef;
def gen_letter =
pickup fine.nib;
top y1r=vround(if not monowidth:.95 fi x_height+oo); x1r=.5w; %top of loop
x5r=.5w; bot y5r=-oo; %bottom of ditto
lft x3r=w-rt x7r=hround(.75u); y3r=y7r=.5[y1r,y5r]; %left and right bulge
filldraw stroke gr_arc.e(1,2,3)(vair,stem,.5otilt) %three quadrants of loop
& gr_arc.e(3,4,5)(vair,stem,.5otilt) & gr_arc.e(5,6,7)(vair,stem,.5otilt);
%we now draw the hook z8..z9..z10. It must satisfy the following constraints:
%its outer contour is symmetric with respect to some axis containing z9l;
%one end is known, the width there is thin_stem, and the width at z10
%is, ideally, stem. (But since we may have to change that we call it Stem.)
z8l=z1l; numeric thin_stem, med_stem; thin_stem=.7[hair,Stem];
%the aperture, measured perpendicular to the axis, equals Stem
numeric apert; apert=2Stem+thin_stem-currentbreadth; %apert=length(z10l-z8l);
numeric left_goal; lft left_goal=vround(lft x3r+.5u); %leftmost tangent known
numeric top_goal; top top_goal=h+oo; %highest tangent known
%if by taking Stem=stem we got apert > top_goal-y1l, the problem might
%not have a solution with a horizontal tangent; in that case the
%constraint is on apert:
if 2stem+.7[hair,stem]-currentbreadth>top_goal-y8l: apert=top_goal-y8l;
else: Stem=stem; fi
%we first estimate the slope of the axis by imagining that, in the vicinity
%of z9l, the hook looks like a semicircle of diameter apert/2.
%(this value is empiric, but reasonable because the tension is high)
z0l=(left_goal+.25apert,top_goal-.25apert); %center of semicircle
numeric axis; axis=angle(z0l-z8l)+angle(length(z0l-z8l)+-+.5apert,.5apert);
z9l=z0l+(.25apert,0)rotated(axis); z10l=z8l+(0,-apert)rotated(axis);
%we now iterate, correcting z9l until the tangencies are satisfied
path hook; numeric left_real; numeric top_real;
forever:
hook:=z8l{dir(axis)}..tension 1.5..z9l..tension 1.5..{-dir(axis)}z10l;
if directiontime up of hook=-1:
left_error:=0; message "hook has no vertical tangent!";
else: left_error:=xpart directionpoint up of hook-left_goal; fi
if directiontime right of hook=-1:
top_error:=0; message "hook has no horizontal tangent!";
else: top_error:=ypart directionpoint right of hook-top_goal; fi
%message "top_error:"; show top_error; message "left_error:"; show left_error;
exitif (abs(left_error)<.05) and (abs(top_error)<.05);
x9l:=x9l-left_error; y9l:=y9l-top_error;
axis:=angle(z9l-z8l)+angle(length(z9l-z8l)+-+.5apert,.5apert);
x10l:=x8l+apert*sind axis; y10l:=y8l-apert*cosd axis;
endfor
pos8(thin_stem,axis-90); pos10(Stem,axis+90); pos9(.3[hair,Stem],axis+180);
filldraw stroke
z7e{z7'e}..{dir axis}z8e..tension 1.5..z9e..tension 1.5..{-dir axis}z10e;
enddef;
cmchar "Lowercase delta";
beginchar("d",dims);
this_letter; penlabels(1,2,3,4,5,6,7,8,9,10); endchar;
if boolean barebones: picture savedpicture; endinput; fi
cmchar "Lowercase sigma followed by delta";
begindoublechar(oct"004",dim_sigma);
mid_sigma; middoublechar(dims); this_letter; endchar;
picture savedpicture;
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