Domain

IndexShape Class

The index shape class provides access to the index bounds of a mesh block. The bounds are split into several domains which can be accessed using a class enum IndexDomain. The IndexDomain can be:

entire:

which allows one to access the starting indices of the full meshblock including ghost zones

interior:

which allows access to the interior of the meshblock excluding ghost cells

inner_x1:

which accesses the ghost zones for “inner” face of a meshblock in the x1 direction

outer_x1:

which accesses the ghost zones for “outer” face of a meshblock in the x1 direction

inner_x2:

which accesses the ghost zones for “inner” face of a meshblock in the x2 direction

outer_x2:

which accesses the ghost zones for “outer” face of a meshblock in the x2 direction

inner_x3:

which accesses the ghost zones for “inner” face of a meshblock in the x3 direction

outer_x3:

which accesses the ghost zones for “outer” face of a meshblock in the x3 direction

The starting and ending indices of each dimension of the index shape can be accessed using the is, ie, js, je, ks, ke methods. Currently, access is limited to three dimensions, if needed it can be extended. In cases where the indices are called often it may be more conveneint to pull out the index bounds of a given domain. The IndexRange struct provides an easy way to group the indices together.

The IndexShape class also provides a means for accessing the number of cells in each dimension of each of the domains. This is provided with the ncellsi, ncellsj, and ncellsk methods.

Below is a diagram illustrating a 2d instance of an IndexShape which we will call cellbounds.

IndexRange Struct

The index range struct simply contains the starting and ending indices as well as a method for returning the total number of cells within the range.

Example Usage

The primary use case of the IndexShape occurs when indexing over the different dimensions. Assuming we have a meshblock pointer given as pmb e.g.

const IndexRange ib = pmb->cellbounds.GetBoundsI(IndexDomain::interior);
const IndexRange jb = pmb->cellbounds.GetBoundsJ(IndexDomain::interior);
const IndexRange kb = pmb->cellbounds.GetBoundsK(IndexDomain::interior);

for( int k = kb.s; k <= kb.e; k++ ){
  for( int j = jb.s; j <= jb.e; j++ ){
    for( int i = ib.s; i <= ib.e; i++ ){
      ... code ..
    }
  }
}