; Creates a cross with an octagon at center.
; nell cross.nll PIC 6 | nellsvg 10 12 cm 0.05 1 > cross.svg
s = 1; "s" makes tips longer with increase.
r = s; "r" makes junction side wider with increase.
a = 2*pi/5; "a" makes tips more pointy with increase.
t1 = 3*s; "t1" makes 3 arms longer with increase.
b1 = acos((s/t1)*cos(a/2)-r/(2*t1)); "b1" is angle of side near junction
c1 = pi-a/2-b1; "c1" is angle of side near point
t2 = 5*s; t2,b2,c2 are long arm versions of t1,b1,c1
b2 = acos((s/t2)*cos(a/2)-r/(2*t2));
c2 = pi-a/2-b2;
T1 : L(r) T(-b1) L(t1) T(-c1) L(s) T(-a) L(s) T(-c1) L(t1) T(-b1); T1 is the 3 short arms
T2 : L(r) T(-b2) L(t2) T(-c2) L(s) T(-a) L(s) T(-c2) L(t2) T(-b2); T2 is longer arm
T3 : L(s) T(pi/4); T3 is a side of octagon
T4 : S(T3,8); T4 is octagon at junction
T5 : M((s-r)/2) S(T2,1) M((s+r)/2) T(pi/4) M(s) T(pi/4); T5 makes longer arm.
T6 : M((s-r)/2) S(T1,1) M((s+r)/2) T(pi/4) M(s) T(pi/4); T6 makes shorter arms.
PIC : P(4.5,5.8) S(T4,1) S(T5,1) S(T6,3);