I'm doing some domain decomposition stuff, and I want to "stitch"
distinct (conforming) meshes together into a single global mesh. The
first step is to implement a "mesh union" operation, and I'll deal with
merging "overlapping" nodes afterwards.
To do this, I wrote a function build_mesh_union, which is pasted below.
Worth adding to MeshTools, or somewhere like that?
David
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AutoPtr<MeshBase> build_mesh_union(std::vector<MeshBase*>& meshes)
{
MeshBase* mesh_union;
for(unsigned int i=0; i<meshes.size(); i++)
{
if(i==0)
{
// Need to initialize mesh_union on the first iteration
AutoPtr<MeshBase> mesh_clone = meshes[0]->clone();
mesh_union = mesh_clone.release();
}
else
{
MeshBase& mesh_i = *meshes[i];
unsigned int node_delta = mesh_union->n_nodes();
unsigned int elem_delta = mesh_union->n_elem();
// need to increment node and element IDs of mesh_i before
copying to mesh_union
MeshBase::node_iterator node_it = mesh_i.nodes_begin();
MeshBase::node_iterator node_end = mesh_i.nodes_end();
for (; node_it != node_end; ++node_it)
{
Node *node = *node_it;
unsigned int new_id = node->id() + node_delta;
node->set_id(new_id);
}
MeshBase::element_iterator elem_it = mesh_i.elements_begin();
MeshBase::element_iterator elem_end = mesh_i.elements_end();
for (; elem_it != elem_end; ++elem_it)
{
Elem *elem = *elem_it;
unsigned int new_id = elem->id() + elem_delta;
elem->set_id(new_id);
}
// Copy mesh data
UnstructuredMesh& mesh_union_unstructured =
libmesh_cast_ref<UnstructuredMesh&>(*mesh_union);
UnstructuredMesh& mesh_i_unstructured =
libmesh_cast_ref<UnstructuredMesh&>(mesh_i);
mesh_union_unstructured.copy_nodes_and_elements(mesh_i_unstructured);
// then decrement node and element IDs of mesh_i to return to
original state
node_it = mesh_i.nodes_begin();
node_end = mesh_i.nodes_end();
for (; node_it != node_end; ++node_it)
{
Node *node = *node_it;
unsigned int new_id = node->id() - node_delta;
node->set_id(new_id);
}
elem_it = mesh_i.elements_begin();
elem_end = mesh_i.elements_end();
for (; elem_it != elem_end; ++elem_it)
{
Elem *elem = *elem_it;
unsigned int new_id = elem->id() - elem_delta;
elem->set_id(new_id);
}
}
}
return AutoPtr<MeshBase>(mesh_union);
}
------------------------------------------------------------------------------
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