This solver serves the same purpose as Calving3D, but whereas the Calving3D solver describes calving using a displacement vector defined on the front, Calving3D_lset returns an implicit level-set function, which is used by CalvingRemeshMMG to slice the mesh. The level-set zero-contour defines the face of the calving event. The level-set variable is negative inside the calved ice, and postive inside the remaining glacier.