--- /dev/null
+
+%
+% Draw an arrow
+%
+% * `stemslant' gives the direction of the stem's left boundary
+% (needed for brushed stems, equals "up" for straight stems)
+% * `extend' is used to make the stem longer or shorter (if negative);
+% different kinds of accidentals need different values here
+%
+def draw_arrow (expr attach, stemwidth, stemslant, extend, pointingdown) =
+begingroup;
+ save htip; % tip height
+ save wwing; % wing `radius'
+ save angle_wing_bot, angle_wing_top, angle_tip;
+ save upshift;
+ clearxy;
+
+ wwing := 0.26 stemwidth;
+ htip := staff_space * 0.85 + stafflinethickness - wwing;
+
+ % `flip' is used to reflect the arrow vertically
+ % if arrow points downward
+ transform flip;
+ if pointingdown:
+ flip = identity reflectedabout (origin, right);
+ else:
+ flip = identity;
+ fi;
+
+ z1 = attach shifted (-stemwidth / 2, 0);
+ upshift := max (0, wwing + 0.1 staff_space + extend);
+ z2 = z1 shifted (((unitvector stemslant)
+ scaled upshift) transformed flip);
+
+ z7 = attach shifted ((stemwidth/2),0);
+ z6 = z7 shifted (((unitvector (-xpart stemslant, ypart stemslant))
+ scaled upshift) transformed flip);
+ z2 - z3 = ( 0.38 staff_space, 0.05 htip) transformed flip;
+ z6 - z5 = (-0.38 staff_space, 0.05 htip) transformed flip;
+
+ z4 = attach shifted ((-0.2 stemwidth, upshift + htip)
+ transformed flip);
+ z4'= attach shifted (( 0.2 stemwidth, upshift + htip)
+ transformed flip);
+
+ % `angle_wing_bot' is the angle at which the arc
+ % from z2 to z3a enters z3a
+ % `angle_wing_top' is the angle at which the arc
+ % from z3b to z4 leaves z3b
+ % `angle_tip' is the angle at which the arc
+ % from z4 to z4' leaves z4
+ angle_wing_bot = 30;
+ angle_wing_top = 55;
+ angle_tip = 68;
+
+ z3a = z3 shifted ((((dir angle_wing_bot) rotated -90)
+ scaled wwing) transformed flip);
+ z3b = z3 shifted ((((dir angle_wing_top) rotated 90)
+ scaled wwing) transformed flip);
+
+ z5a = z5 shifted ((((dir (180 - angle_wing_bot)) rotated 90)
+ scaled wwing) transformed flip);
+ z5b = z5 shifted ((((dir (180 - angle_wing_top)) rotated -90)
+ scaled wwing) transformed flip);
+
+ % Draw the arrow
+ pickup pencircle scaled 1;
+ fill z1
+ -- z2{stemslant transformed flip}
+ .. {(-dir angle_wing_bot) transformed flip}z3a
+ .. z3b{(dir angle_wing_top) transformed flip}
+ .. z4{(dir angle_tip) transformed flip}
+ .. z4'{(dir (-angle_tip)) transformed flip}
+ .. {(dir (-angle_wing_top)) transformed flip}z5b
+ .. z5a{(-dir (-angle_wing_bot)) transformed flip}
+ .. z6{((-stemslant) reflectedabout (origin, up)) transformed flip}
+ -- z7
+ -- cycle;
+
+ labels (range 0 thru 7, 4', 3a, 3b, 5a, 5b);
+endgroup;
+enddef;