belowGroups = name of the group of volumes below the cut plane
nx ny nz = vector normal to the cut plane
px py pz = a point of the cut plane
- T = 0 < T < 1 : vertices of a tetrahedron are considered as belonging
+ T = 0 < T < 1 : vertices of a tetrahedron are considered as belonging to
the cut plane if their distance to the plane is inferior to L*T
where L is the mean edge size of the tetrahedron