Algorithm is: 1) find all edge crossings 2) optionally discard any triangles with all vertex distances < epsilon. 3) Do edge splits at crossings 4 option a) (optionally) delete all vertices on positive side 4 option b) (OR optionally) disconnect all triangles w/ vertices on positive side (if keeping both sides) 4 option c) do nothing (if keeping both sides and not disconnecting them) 5) (optionally) collapse any degenerate boundary edges 6) (optionally) change an attribute tag for all triangles on positive side 7) find loops through valid boundary edges (ie connected to splits, or on-plane edges) (if second half was kept, do this separately for each separate mesh ID label)