getFaceNormal method
Compute the normal of a face from its vertices
Implementation
Vec3 getFaceNormal(int i, final Vec3 target) {
final List<int> f = faces[i];
final Vec3 va = vertices[f[0]];
final Vec3 vb = vertices[f[1]];
final Vec3 vc = vertices[f[2]];
return ConvexPolyhedron.computeNormal(va, vb, vc, target);
}