B Comparison of area interactions to other approaches

B.1 Local area interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 B.2 Global area interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

As we have discussed in [102], the following definition of local area is both force-and torque-free:

Fal(A) = − 1|tA|2 + |tB |2 + |tC |2 kal∆SABCtA,

where T is the centroid of triangle ABC and tA = T − A, with analogous expressions for vertices B and C.