classification in simmetrix mesh converter

[cwsmith]

From the discussion in the TOMMS issue here: https://github.com/SCOREC/tomms/issues/17

The simmetrix -> omegah mesh converter is calling classify_equal_order to set the geometric model entity id and dimension:

omega_h/src/Omega_h_meshsim.cpp

Line 136 in 1235d6f

classify_equal_order(mesh, ent_dim, eqv2v, host_class_id.write());

clasify_equal_order is defined here:

omega_h/src/Omega_h_class.cpp

Lines 168 to 190 in 1235d6f

	void classify_equal_order(
	Mesh* mesh, Int ent_dim, LOs eqv2v, Read<ClassId> eq_class_ids) {
	LOs eq2e;
	if (ent_dim == mesh->dim()) {
	/* assuming elements were constructed in the same order ! */
	eq2e = LOs(mesh->nelems(), 0, 1);
	} else if (ent_dim == VERT) {
	eq2e = eqv2v;
	} else {
	Write<LO> eq2e_w;
	Write<I8> codes;
	auto ev2v = mesh->ask_verts_of(ent_dim);
	auto v2e = mesh->ask_up(VERT, ent_dim);
	find_matches(mesh->family(), ent_dim, eqv2v, ev2v, v2e, &eq2e_w, &codes);
	eq2e = eq2e_w;
	}
	auto neq = eqv2v.size() / (ent_dim + 1);
	auto eq_class_dim = Read<I8>(neq, I8(ent_dim));
	auto class_dim =
	map_onto(eq_class_dim, eq2e, mesh->nents(ent_dim), I8(mesh->dim()), 1);
	auto class_id = map_onto(eq_class_ids, eq2e, mesh->nents(ent_dim), -1, 1);
	mesh->add_tag<I8>(ent_dim, "class_dim", 1, class_dim);
	mesh->add_tag<ClassId>(ent_dim, "class_id", 1, class_id);

It isn't clear if this is necessary since we are explicitly querying the classification info from simmetrix; I suspect we can just set the "class_dim" and "class_id" tags directly.

[joshia5]

@cwsmith , setting the "class_dim" and "class_id" tags directly will only work for elements and vertices, not for other entities because they are created using omegah build functions:

omega_h/src/Omega_h_meshsim.cpp

Line 133 in 1235d6f

build_from_elems_and_coords(

I think a thorough fix would be to create omegah mesh entities while preserving mapping of ids with simmetrix mesh ents and then we can set the tags directly. This build process was implemented for mixed mesh here:

omega_h/src/Omega_h_meshsim.cpp

Line 111 in d96f537

mesh->set_ents(Topo_type::edge, Topo_type::vertex, Adj(ev2v));

although iirc specific omegah functions for mixed mesh building were created for that.

[cwsmith]

This is resolved with #15 .