Function t8_forest_element_face_neighbor

Function Documentation

t8_gloidx_t t8_forest_element_face_neighbor(t8_forest_t forest, t8_locidx_t ltreeid, const t8_element_t *elem, t8_element_t *neigh, const t8_eclass_t neigh_eclass, int face, int *neigh_face)

Construct the face neighbor of an element, possibly across tree boundaries.

Returns the global tree-id of the tree in which the neighbor element lies in.

Parameters:

  • forest – [in] The forest.

  • ltreeid – [in] The local tree in which the element lies.

  • elem – [in] The element to be considered.

  • neigh – [inout] On input an allocated element of the scheme of the face_neighbors eclass. On output, this element’s data is filled with the data of the face neighbor. If the neighbor does not exist the data could be modified arbitrarily.

  • neigh_eclass – [in] The eclass of neigh.

  • face – [in] The number of the face along which the neighbor should be constructed.

  • neigh_face – [out] The number of the face viewed from perspective of neigh. Can be nullptr, in which case the output is discarded.

Returns:

The global tree-id of the tree in which neigh is in. -1 if there exists no neighbor across that face. Domain boundary. -2 if the neighbor is not in a local tree or ghost tree. Process/Ghost boundary.