func (sheep *Sheeple) wander(n *lib.SimNode, t lib.Torus) {
// Move in random direction
sheep.LastP.CopyVec(n.P)
sheep.RandSteer()
sheep.Move(n.P)
t.Map(n.P)
}
func (b Speaker) Heard(n *lib.SimNode, m *lib.SimNode, t lib.Torus) bool {
return t.Explodes(b.R, n.P, m.P)
}