ybc: 10
xbc0: 2
t = 0 (slider from 0 to 20, step 1)
vbc: 1
xbc: xbc0 + (vbc * t)
B: (xbc, ybc)
Lst: {-2, -1, 1, 2, 1, -1}
xab: Lst(Mod[t, 6] + 1)
xac: xab + xbc
Lbraccio: 9
A: (xac, y(B) - Lbraccio)
u = Vector(B, A)