X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=mf%2Fparmesan-macros.mf;h=762a178441bbfc8af9fa9163021b377fad1e2d26;hb=HEAD;hp=6fd040c53168d10077b981311a993cea3261a83d;hpb=91396985dc33de5b35785fcdef2145301c0fccc6;p=lilypond.git

diff --git a/mf/parmesan-macros.mf b/mf/parmesan-macros.mf
index 6fd040c531..762a178441 100644
--- a/mf/parmesan-macros.mf
+++ b/mf/parmesan-macros.mf
@@ -1,10 +1,21 @@
-% -%-Fundamental-%- -*-Metafont-*-
-% parmesan-macros.mf -- macros for parmesan font
-% 
-% source file of LilyPond's pretty-but-neat music font
-% 
-% (c) 2001--2006 Juergen Reuter <reuter@ipd.uka.de>
+% Feta (not the Font-En-Tja) music font -- macros for parmesan font
+% This file is part of LilyPond, the GNU music typesetter.
+%
+% Copyright (C) 2001--2015 Juergen Reuter <reuter@ipd.uka.de>
 % 
+%
+% The LilyPond font 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, or under the SIL Open Font License.
+%
+% LilyPond 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 LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 
 
 %
@@ -26,7 +37,7 @@ def find_tangent (expr p, curve, p_in, p_out) =
 		mid := 0.5 [in, out];
 		exitif abs (out - mid) <= eps;
 		t := xpart (curve intersectiontimes (p -- mid));
-		if (t > 0):
+		if t > 0:
 			in := mid;
 			t_good := t;
 		else:
@@ -47,7 +58,7 @@ enddef;
 %
 def find_tangent_shift (expr line, curve, p_in, p_out) =
 	begingroup;
-	save mid, t, t_good, in, out;
+	save mid, t, in, out;
 	pair mid, in, out;
 
 	in := p_in;
@@ -57,9 +68,8 @@ def find_tangent_shift (expr line, curve, p_in, p_out) =
 		mid := 0.5 [in, out];
 		exitif abs (out - mid) <= eps;
 		t := xpart ((curve shifted mid) intersectiontimes line);
-		if (t > 0):
+		if t > 0:
 			in := mid;
-			t_good := t;
 		else:
 			out := mid;
 		fi;
@@ -91,6 +101,15 @@ def get_subpath (expr curve, dir_in, dir_out, offset) =
 enddef;
 
 
+%
+% Get point specified by `dir_' of `curve' which is then
+% shifted by `offset'.
+%
+def get_subpoint (expr curve, dir_, offset) =
+	(directionpoint dir_ of curve) shifted offset
+enddef;
+
+
 %
 % This is the same as `get_subpath', except that the time values
 % used to construct the resulting subpath are rounded to integers.
@@ -111,4 +130,97 @@ def get_subpath_i (expr curve, dir_in, dir_out, offset) =
 	endgroup
 enddef;
 
+
+%
+% Find envelope cusp created by `object' moved along `curve', using
+% step value `s' for initial intermediate points.  `s' must be small
+% enough so that this macro finds at least one point on the envelope
+% between the `entrance' and `exit' points of the cusp which has
+% a significantly different direction vector.
+%
+% This function returns a time value on `curve'; if there is no
+% cusp, it returns -1.
+%
+def find_envelope_cusp (expr object, curve, s) =
+	begingroup;
+	save mid, p, t, t_good, delta, start, stop, do_exit;
+	pair p[];
+	boolean do_exit;
+
+	p0 := (directionpoint (direction 0 of curve) of object)
+		shifted (point 0 of curve);
+	p1 := (directionpoint (direction s of curve) of object)
+		shifted (point s of curve);
+
+	t := s;
+
+	forever:
+		t := t + s;
+		exitif t >= length curve;
+
+		p2 := (directionpoint (direction t of curve) of object)
+			shifted (point t of curve);
+		if p2 <> p1:
+			delta := angle (p2 - p1) - angle (p1 - p0);
+			if delta > 180:
+				delta := delta - 360;
+			fi;
+
+			% we check for a direction change by more than
+			% than 45 degrees
+			if abs (delta) >= 45:
+				do_exit := true;
+			else:
+				do_exit := false;
+			fi;
+
+			p0 := p1;
+			p1 := p2;
+		fi;
+
+		% having `exitif' within an if-clause doesn't work
+		exitif do_exit;
+	endfor;
+
+	if t >= length curve:
+		t_good := -1;
+	else:
+		% the wanted point lies between `t - s' and `t'
+		start := t - s;
+		stop := t;
+		t_good := start;
+
+		forever:
+			mid := 0.5 [start, stop];
+			exitif abs (stop - mid) <= eps;
+
+			p0 := (directionpoint (direction start of curve)
+				of object) shifted (point start of curve);
+			p1 := (directionpoint (direction mid of curve)
+				of object) shifted (point mid of curve);
+			p2 := (directionpoint (direction stop of curve)
+				of object) shifted (point stop of curve);
+
+			exitif (length (p1 - p0) = 0)
+				or (length (p2 - p1) = 0);
+
+			delta := angle (p2 - p1) - angle (p1 - p0);
+			if delta > 180:
+				delta := delta - 360;
+			fi;
+
+			if abs (delta) >= 45:
+				stop := mid;
+				t_good := mid;
+			else:
+				start := mid;
+				t_good := stop;
+			fi;
+		endfor;
+	fi;
+
+	t_good
+	endgroup
+enddef;
+
 % EOF