p4est  1.1
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
Data Fields
p4est_mesh_t Struct Reference

This structure contains complete mesh information on the forest. More...

#include <p4est_mesh.h>

Data Fields

p4est_locidx_t local_num_quadrants
p4est_locidx_t ghost_num_quadrants
 tree index for each local quad, NULL by default
int * ghost_to_proc
 processor for each ghost quad
 one index for each of the 4 faces
int8_t * quad_to_face
 encodes orientation/2:1 status
 stores half-size neighbors
 stores lists of per-level quads, NULL by default
p4est_locidx_t local_num_corners

Detailed Description

This structure contains complete mesh information on the forest.

It stores the locally relevant neighborhood, that is, all locally owned quadrants and one layer of adjacent ghost quadrants and their owners.

For each local quadrant, its tree number is stored in quad_to_tree. The quad_to_tree array is NULL by default and can be enabled using p4est_mesh_new_ext. For each ghost quadrant, its owner rank is stored in ghost_to_proc. For each level, an array of local quadrant numbers is stored in quad_level. The quad_level array is NULL by default and can be enabled using p4est_mesh_new_ext.

The quad_to_quad list stores one value for each local quadrant's face. This value is in 0..local_num_quadrants-1 for local quadrants, or in local_num_quadrants + (0..ghost_num_quadrants-1) for ghost quadrants. The quad_to_face list has equally many entries which are either:

  1. A value of v = 0..7 indicates one same-size neighbor. This value is decoded as v = r * 4 + nf, where nf = 0..3 is the neighbor's connecting face number and r = 0..1 is the relative orientation of the neighbor's face, see p4est_connectivity.h.
  2. A value of v = 8..23 indicates a double-size neighbor. This value is decoded as v = 8 + h * 8 + r * 4 + nf, where r and nf are as above and h = 0..1 is the number of the subface.
  3. A value of v = -8..-1 indicates two half-size neighbors. In this case the corresponding quad_to_quad index points into the quad_to_half array which stores two quadrant numbers per index, and the orientation of the smaller faces follows from 8 + v. The entries of quad_to_half encode between local and ghost quadrant in the same way as the quad_to_quad values described above. A quadrant on the boundary of the forest sees itself and its face number.

The quad_to_corner list stores corner neighbors that are not face neighbors. On the inside of a tree, there is precisely one such neighbor per corner. In this case, its index is encoded as described above for quad_to_quad. The neighbor's matching corner number is always diagonally opposite.

On the inside of an inter-tree face, we have precisely one corner neighbor. If a corner is an inter-tree corner, then the number of corner neighbors may be any non-negative number. In both cases, the quad_to_corner value is in local_num_quadrants + local_num_ghosts + [0 .. local_num_corners - 1] where the offset by local quadrants and ghosts is implicitly substracted. It indexes into corner_offset, which encodes a group of corner neighbors. Each group contains the quadrant numbers encoded as usual for quad_to_quad in corner_quad, and the corner number from the neighbor as corner_corner.

Intra-tree corners and corners across an inter-tree face are implemented. Other Inter-tree corners are NOT IMPLEMENTED and are assigned the value -2. Corners with no diagonal neighbor at all are assigned the value -1.

The documentation for this struct was generated from the following file: