ScdInterface.hpp

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/** \file ScdInterface.hpp
 */
#ifndef SCD_INTERFACE
#define SCD_INTERFACE

#include "moab/Interface.hpp"
#include "moab/HomXform.hpp"

#include <iostream>
#include <vector>
#include <cassert>

#include "moab/win32_config.h"

namespace moab
{

class StructuredElementSeq;
class EntitySequence;
class ScdVertexData;
class EntitySequence;
class ScdBox;
class ParallelComm;

/** \class ScdInterface ScdInterface.hpp "moab/ScdInterface.hpp"
 * \brief A structured mesh interface for MOAB-based data
 *
 * Structured mesh in MOAB is created and accessed through the ScdInterface and ScdBox classes.
 *
 * \section Construction Construction and Representation
 * Structured mesh can be constructed in one of two ways.  First, a rectangular block of mesh,
 * both vertices and edges/quads/hexes, can be created in one shot, using the construct_box method.
 * In this case, there are single sequences of vertices/entities.  The second method for creating
 * structured mesh is to create the structured blocks of vertices and elements separately.  In
 * this case, different blocks of elements can share blocks of vertices, and each block of
 * elements has its own independent parametric space.  The algorithms behind this representation
 * are described in T. Tautges, "MOAB-SD: Integrated structured and unstructured mesh
 * representation", Eng. w Comp, vol 20 no. 3.
 *
 * Structured mesh is represented in MOAB down at the element sequence level, which is something
 * applications don't see.  In addition, when structured mesh is created, entity sets are also
 * created and tagged with information about the parametric space.  In particular, the BOX_DIMS
 * tag is used to indicate the lower and upper corners in parametric space (this
 * tag is integer size 6).  Structured mesh blocks are also available through ScdBox class objects
 * returned by ScdInterface.  These class objects should be treated only as references to the
 * structured mesh blocks; that is, the structured mesh referenced by these objects is not deleted
 * when the ScdBox instance is destroyed.  Functions for destroying the actual mesh are available
 * on this class, though.
 *
 * Structured mesh blocks are returned in the form of ScdBox class objects.  Each ScdBox instance
 * represents a rectangular block of vertices and possibly elements (edges, quads, or hexes).  The
 * edge/quad/hex entity handles for a ScdBox are guaranteed to be contiguous, starting at a starting
 * value which is also available through the ScdBox class.  However, vertex handles may or may not
 * be contiguous, depending on the construction method.  The start vertex handle is also available
 * from the ScdBox class.
 *
 * \section Parameters Parametric Space
 *
 * Each structured box has a parametric (ijk) space, which can be queried through the ScdBox
 * interface. For non-periodic boxes, the edge/quad/hex parameter bounds are one less in each
 * dimension than that of the vertices, otherwise they are the same as the vertex parameter bounds.
 * In a parallel representation, boxes are locally non-periodic by default, but global ids are
 * assigned such that the last set of vertices in a periodic direction match those of the first set
 * of vertices in that direction.
 *
 * Entity handles are allocated with the i parameter varying fastest, then j, then k.
 *
 * \section Per Periodic Meshes
 * Boxes can be periodic in i, or j, or both i and j.  If only i or j is periodic, the corresponding
 * mesh is a strip or an annular cylinder; if both i and j are periodic, the corresponding mesh is
 * an annular torus.  A box cannot be periodic in all three parameters.  If i and/or j is periodic,
 * and assuming IMIN/JMIN is zero, the parameter extents in the/each periodic direction (IMAX/JMAX)
 * for vertices and edges/faces/hexes are the same, and the vertices on the "top" end in the
 * periodic direction are at parameter value IMIN/JMIN.
 *
 * \section Par Parallel Representation
 *
 * For parallel structured meshes, each local mesh (the mesh on a given process) looks like a
 * non-periodic structured mesh, and there are both local and global parameters of the structured
 * mesh.  If the mesh is periodic in a given direction, the last process in the periodic direction
 * has local IMAX/JMAX that is one greater than the global IMAX/JMAX.
 *
 *
 * In parallel, the periodicity described in the previous paragraph is "local periodicity"; there is
 * also the notion of global periodicity.  For serial meshes, those concepts are the same.  In
 * parallel, a mesh can be locally non-periodic but globally periodic in a given direction.  In that
 * case, the local mesh is still non-periodic, i.e. the parametric extents for edges is one fewer
 * than that of vertices in that direction. However, vertices are given global ids such that they
 * match those of the parametric minimum in that direction. Geometric positions of the vertices at
 * the high end should still be greater than the ones just below.
 *
 * \section Adjs Adjacent Entities
 * This interface supports parametric access to intermediate-dimension entities, e.g. adjacent faces
 * and edges in a 3d mesh.  In this case, a direction parameter is added, to identify the parametric
 * direction of the entities being requested.  For example, to retrieve the faces adjacent to a hex
 * with parameters ijk, in the i parametric direction, you would use the parameters ijk0.  These
 * intermediate entities are not stored in a structured representation, but their parametric
 * positions can be evaluated based on their adjacencies to higher-dimensional entities.  Thanks to
 * Milad Fatenejad for the thinking behind this.
 *
 * \section Evaluation Evaluation
 * The ScdBox class provides functions for evaluating the mesh based on the ijk parameter space.
 * These functions are inlined where possible, for efficiency.
 */

//! struct for keeping parallel data in one place
class ScdParData
{
  public:
    ScdParData() : partMethod( NOPART ), pComm( NULL )
    {
        gDims[0] = gDims[1] = gDims[2] = gDims[3] = gDims[4] = gDims[5] = 0;
        gPeriodic[0] = gPeriodic[1] = gPeriodic[2] = 0;
        pDims[0] = pDims[1] = pDims[2] = 0;
    }

    //! Partition method enumeration; these strategies are described in comments for
    //! compute_partition_alljorkori, compute_partition_alljkbal, compute_partition_sqij,
    //! compute_partition_sqjk, and compute_partition_sqijk
    enum PartitionMethod
    {
        ALLJORKORI = 0,
        ALLJKBAL,
        SQIJ,
        SQJK,
        SQIJK,
        TRIVIAL,
        RCBZOLTAN,
        NOPART
    };

    //! Partition method names
    static MOAB_EXPORT const char* PartitionMethodNames[NOPART + 1];

    //! partition method used to partition global parametric space
    int partMethod;

    //! lower and upper corners of global box
    int gDims[6];

    //! is globally periodic in i or j or k
    int gPeriodic[3];

    //! number of procs in each direction
    int pDims[3];

    //! parallel communicator object for this par scd mesh
    ParallelComm* pComm;
};

class MOAB_EXPORT ScdInterface
{
  public:
    friend class ScdBox;

    //! Constructor
    /** Constructor; if find_boxes is true, this will search for entity sets marked as
     * structured blocks, based on the BOX_DIMS tag.  Structured mesh blocks will be stored
     * in this interface class for future retrieval.  Structured mesh blocks created through
     * this interface will also be stored here.
     * \param impl MOAB instance
     * \param find_boxes If true, search all the entity sets, caching the structured mesh blocks
     */
    ScdInterface( Interface* impl, bool find_boxes = false );

    // Destructor
    ~ScdInterface();

    //! Return the MOAB Interface instance *
    Interface* impl() const;

    //! Construct new structured mesh box, including both vertices and elements
    /** Parameter range
     * for vertex box is [low-high], for elements is [low-high).  Construct quads by passing
     * in low[2] == high[2], and edges by passing in low[1] == high[1] and low[2] == high[2].
     * The result is passed back in a ScdBox*, which is a *reference* to the box of structured mesh.
     * That is, the actual mesh is retained in MOAB when the ScdBox is destroyed.  To actually
     * destroy the mesh, call the destroy_mesh function on the ScdBox object first, before
     * destroying it. \param low Lower corner in parameter space \param high Higher corner in
     * parameter space \param coords Coordinates of vertices, interleaved (xyzxyz...); if NULL,
     * coords are set to parametric values \param num_coords Number of coordinate values \param
     * new_box Reference to box of structured mesh \param lperiodic[3] If lperiodic[s] != 0,
     * direction s is locally periodic \param par_data If non-NULL, this will get stored on the
     * ScdBox once created, contains info about global parallel nature of ScdBox across procs \param
     * assign_global_ids If true, assigns 1-based global ids to vertices using GLOBAL_ID_TAG_NAME
     * \param resolve_shared_ents If != -1, resolves shared entities up to and including dimension
     * equal to value
     */
    ErrorCode construct_box( HomCoord low, HomCoord high, const double* const coords, unsigned int num_coords,
                             ScdBox*& new_box, int* const lperiodic = NULL, ScdParData* const par_data = NULL,
                             bool assign_global_ids = false, int resolve_shared_ents = -1 );

    //! Create a structured sequence of vertices, quads, or hexes
    /** Starting handle for the sequence is available from the returned ScdBox.
     * If creating a structured quad or hex box, subsequent calls must be made to ScdBox::add_vbox,
     * until all the vertices have been filled in for the box.
     * \param low Lower corner of structured box
     * \param high Higher corner of structured box
     * \param type EntityType, one of MBVERTEX, MBEDGE, MBQUAD, MBHEX
     * \param starting_id Requested start id of entities
     * \param new_box Reference to the newly created box of entities
     * \param is_periodic[3] If is_periodic[s] is non-zero, mesh should be periodic in direction s
     * (s=[0,1,2])
     */
    ErrorCode create_scd_sequence( const HomCoord& low, const HomCoord& high, EntityType type, int starting_id,
                                   ScdBox*& new_box, int* is_periodic = NULL );

    //! Return all the structured mesh blocks in this MOAB instance, as ScdBox objects
    /** Return the structured blocks in this MOAB instance.  If these were not searched for
     * at instantiation time, then the search is done now.
     * \param boxes Vector of ScdBox objects representing structured mesh blocks
     */
    ErrorCode find_boxes( std::vector< ScdBox* >& boxes );

    //! Return all the structured mesh blocks in this MOAB instance, as entity set handles
    /** Return the structured blocks in this MOAB instance.  If these were not searched for
     * at instantiation time, then the search is done now.
     * \param boxes Range of entity set objects representing structured mesh blocks
     */
    ErrorCode find_boxes( Range& boxes );

    //! Return all the structured mesh blocks known by ScdInterface (does not search)
    /** Return the structured blocks in this ScdInterface instance.  Does not search for new boxes,
     * just returns the contents of the list.
     * \param boxes Structured boxes
     */
    ErrorCode get_boxes( std::vector< ScdBox* >& boxes );

    //! Return the tag marking the lower and upper corners of boxes
    /**
     * \param create_if_missing If the tag does not yet exist, create it
     */
    Tag box_dims_tag( bool create_if_missing = true );

    //! Return the tag marking the global lower and upper corners of boxes
    /**
     * \param create_if_missing If the tag does not yet exist, create it
     */
    Tag global_box_dims_tag( bool create_if_missing = true );

    //! Return the tag marking the partitioning method used to partition the box in parallel
    /**
     * \param create_if_missing If the tag does not yet exist, create it
     */
    Tag part_method_tag( bool create_if_missing = true );

    //! Return the tag marking whether box is periodic in i and j
    /**
     * \param create_if_missing If the tag does not yet exist, create it
     */
    Tag box_periodic_tag( bool create_if_missing = true );

    //! Return the tag marking the ScdBox for a set
    /**
     * \param create_if_missing If the tag does not yet exist, create it
     */
    Tag box_set_tag( bool create_if_missing = true );

    //! Return the ScdBox corresponding to the entity set passed in
    /** If the entity isn't a structured box set, NULL is returned.
     * \param eh Entity whose box is being queried
     */
    ScdBox* get_scd_box( EntityHandle eh );

    //! Compute a partition of structured parameter space
    /** Compute a partition of structured parameter space, based on data in the ScdParData
     * passed in.  Results are passed back in arguments, which application can set back into
     * par_data argument if they so desire.
     * \param np Number of processors
     * \param nr Rank of this processor
     * \param par_data ScdParData object that contains input global parameter space, desired
     *           partitioning method, and information about global periodicity.
     * \param ldims Local parameters for grid
     * \param lperiodic Whether or not a given dimension is locally periodic
     * \param pdims Number of procs in i, j, k directions
     */
    static ErrorCode compute_partition( int np, int nr, const ScdParData& par_data, int* ldims, int* lperiodic = NULL,
                                        int* pdims = NULL );

    //! Get information about the neighbor in the dijk[] direction, where dijk can be -1 or 1 for
    //! all 3 params
    /** Get information about the neighbor in the dijk[] direction, where dijk can be -1 or 1 for
     * all 3 params \param np (in) Total # procs \param nr Processor from which neighbor is
     * requested \param spd (in) ScdParData containing part method, gdims, gperiodic data \param
     * dijk(*) (in) Direction being queried, = +/-1 or 0 \param pto (out) Processor holding the
     * destination part \param rdims(6) (out) Parametric min/max of destination part \param
     * facedims(6) (out) Parametric min/max of interface between pfrom and pto; if at the max in a
     * periodic direction, set to global min of that direction \param across_bdy(3) (out) If
     * across_bdy[i] is -1(1), interface with pto is across periodic lower(upper) bdy in parameter
     * i, 0 otherwise
     */
    static ErrorCode get_neighbor( int np, int nr, const ScdParData& spd, const int* const dijk, int& pto, int* rdims,
                                   int* facedims, int* across_bdy );

    //! Tag vertices with sharing data for parallel representations
    /** Given the ParallelComm object to use, tag the vertices shared with other processors
     */
    ErrorCode tag_shared_vertices( ParallelComm* pcomm, EntityHandle seth );

    //! Tag vertices with sharing data for parallel representations
    /** Given the ParallelComm object to use, tag the vertices shared with other processors
     */
    ErrorCode tag_shared_vertices( ParallelComm* pcomm, ScdBox* box );

  protected:
    //! Remove the box from the list on ScdInterface
    ErrorCode remove_box( ScdBox* box );

    //! Add the box to the list on ScdInterface
    ErrorCode add_box( ScdBox* box );

  private:
    //! Create an entity set for a box, and tag with the parameters
    /** \param low Lower corner parameters for this box
     * \param high Upper corner parameters for this box
     * \param scd_set Entity set created
     * \param is_periodic[3] If is_periodic[s] is non-zero, mesh should be periodic in direction s
     * (s=[0,1,2])
     */
    ErrorCode create_box_set( const HomCoord& low, const HomCoord& high, EntityHandle& scd_set,
                              int* is_periodic = NULL );

    //! Compute a partition of structured parameter space
    /** Partitions the structured parametric space by partitioning j, k, or i only.
     * If j is greater than #procs, partition that, else k, else i.
     * For description of arguments, see ScdInterface::compute_partition.
     */
    inline static ErrorCode compute_partition_alljorkori( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                          int* lijk, int* lperiodic, int* pijk );

    //! Compute a partition of structured parameter space
    /** Partitions the structured parametric space by partitioning j, and possibly k,
     * seeking square regions of jk space
     * For description of arguments, see ScdInterface::compute_partition.
     */
    inline static ErrorCode compute_partition_alljkbal( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                        int* lijk, int* lperiodic, int* pijk );

    //! Compute a partition of structured parameter space
    /** Partitions the structured parametric space by seeking square ij partitions
     * For description of arguments, see ScdInterface::compute_partition.
     */
    inline static ErrorCode compute_partition_sqij( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                    int* lijk, int* lperiodic, int* pijk );

    //! Compute a partition of structured parameter space
    /** Partitions the structured parametric space by seeking square jk partitions
     * For description of arguments, see ScdInterface::compute_partition.
     */
    inline static ErrorCode compute_partition_sqjk( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                    int* lijk, int* lperiodic, int* pijk );

    //! Compute a partition of structured parameter space
    /** Partitions the structured parametric space by seeking square ijk partitions
     * For description of arguments, see ScdInterface::compute_partition.
     */
    inline static ErrorCode compute_partition_sqijk( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                     int* lijk, int* lperiodic, int* pijk );

    //! Get vertices shared with other processors
    /** Shared vertices returned as indices into each proc's handle space
     * \param box Box used to get parametric space info
     * \param procs Procs this proc shares vertices with
     * \param offsets Offsets into indices list for each proc
     * \param shared_indices local/remote indices of shared vertices
     */
    static ErrorCode get_shared_vertices( ParallelComm* pcomm, ScdBox* box, std::vector< int >& procs,
                                          std::vector< int >& offsets, std::vector< int >& shared_indices );

    static ErrorCode get_indices( const int* const ldims, const int* const rdims, const int* const across_bdy,
                                  int* face_dims, std::vector< int >& shared_indices );

    static ErrorCode get_neighbor_alljorkori( int np, int pfrom, const int* const gdims, const int* const gperiodic,
                                              const int* const dijk, int& pto, int* rdims, int* facedims,
                                              int* across_bdy );

    static ErrorCode get_neighbor_alljkbal( int np, int pfrom, const int* const gdims, const int* const gperiodic,
                                            const int* const dijk, int& pto, int* rdims, int* facedims,
                                            int* across_bdy );

    static ErrorCode get_neighbor_sqij( int np, int pfrom, const int* const gdims, const int* const gperiodic,
                                        const int* const dijk, int& pto, int* rdims, int* facedims, int* across_bdy );

    static ErrorCode get_neighbor_sqjk( int np, int pfrom, const int* const gdims, const int* const gperiodic,
                                        const int* const dijk, int& pto, int* rdims, int* facedims, int* across_bdy );

    static ErrorCode get_neighbor_sqijk( int np, int pfrom, const int* const gdims, const int* const gperiodic,
                                         const int* const dijk, int& pto, int* rdims, int* facedims, int* across_bdy );

    static int gtol( const int* gijk, int i, int j, int k );

    //! assign global ids to vertices in this box
    ErrorCode assign_global_ids( ScdBox* box );

    //! interface instance
    Interface* mbImpl;

    //! whether we've searched the database for boxes yet
    bool searchedBoxes;

    //! structured mesh blocks; stored as ScdBox objects, can get sets from those
    std::vector< ScdBox* > scdBoxes;

    //! tag representing whether box is periodic in i and j
    Tag boxPeriodicTag;

    //! tag representing box lower and upper corners
    Tag boxDimsTag;

    //! tag representing global lower and upper corners
    Tag globalBoxDimsTag;

    //! tag representing partition method
    Tag partMethodTag;

    //! tag pointing from set to ScdBox
    Tag boxSetTag;
};

class MOAB_EXPORT ScdBox
{
    friend class ScdInterface;

  public:
    //! Destructor
    ~ScdBox();

    //! Return the ScdInterface responsible for this box
    inline ScdInterface* sc_impl() const;

    //! Add a vertex box to this box
    /* Add a vertex box to the element sequence referenced by this box.  The passed in vbox must
     * be a vertex box, with parametric extents no larger than that of this box.  This vbox is
     * oriented to this box by matching parameters from1-from3 in vbox to to1-to3 in this box.
     * If bb_input is true, only the part of the vertex sequence between bb_min and bb_max is
     * referenced \param vbox The vertex box being added to this box \param from1 1st reference
     * point on vbox \param to1 1st reference point on this box \param from2 2nd reference point on
     * vbox \param to2 2nd reference point on this box \param from3 3rd reference point on vbox
     * \param to3 3rd reference point on this box
     * \param bb_input If true, subsequent parameters list extents of vbox referenced
     * \param bb_min Lower corner of rectangle referenced
     * \param bb_max Upper corner of rectangle referenced
     */
    ErrorCode add_vbox( ScdBox* vbox, HomCoord from1, HomCoord to1, HomCoord from2, HomCoord to2, HomCoord from3,
                        HomCoord to3, bool bb_input = false, const HomCoord& bb_min = HomCoord::getUnitv( 0 ),
                        const HomCoord& bb_max = HomCoord::getUnitv( 0 ) );
    // const HomCoord &bb_min = HomCoord::unitv[0],
    // const HomCoord &bb_max = HomCoord::unitv[0]);

    //! Return whether this box has all its vertices defined
    /** Tests whether vertex boxs added with add_vbox have completely defined the vertex parametric
     * space for this box.
     *
     */
    bool boundary_complete() const;

    //! Return highest topological dimension of box
    inline int box_dimension() const;

    //! Starting vertex handle for this box
    inline EntityHandle start_vertex() const;

    //! Starting entity handle for this box
    /** If this is a vertex box, the start vertex handle is returned.
     */
    inline EntityHandle start_element() const;

    //! Return the number of elements in the box
    /* Number of elements is (boxSize[0]-1)(boxSize[1]-1)(boxSize[2]-1)
     */
    inline int num_elements() const;

    //! Return the number of vertices in the box
    /* Number of vertices is boxSize[0] * boxSize[1] * boxSize[2]
     */
    inline int num_vertices() const;

    //! Return the parametric coordinates for this box
    /**
     * \return IJK parameters of lower and upper corners
     */
    inline const int* box_dims() const;

    //! Return the lower corner parametric coordinates for this box
    inline HomCoord box_min() const;

    //! Return the upper corner parametric coordinates for this box
    inline HomCoord box_max() const;

    //! Return the parameter extents for this box
    inline HomCoord box_size() const;

    //! Return the parametric extents for this box
    /**
     * \param ijk IJK extents of this box
     */
    inline void box_size( int* ijk ) const;

    //! Return the parametric extents for this box
    /**
     * \param i I extent of this box
     * \param j J extent of this box
     * \param k K extent of this box
     */
    void box_size( int& i, int& j, int& k ) const;

    //! Get the element at the specified coordinates
    /**
     * \param ijk Parametric coordinates being evaluated
     */
    EntityHandle get_element( const HomCoord& ijk ) const;

    //! Get the element at the specified coordinates
    /**
     * \param i Parametric coordinates being evaluated
     * \param j Parametric coordinates being evaluated
     * \param k Parametric coordinates being evaluated
     */
    EntityHandle get_element( int i, int j = 0, int k = 0 ) const;

    //! Get the vertex at the specified coordinates
    /**
     * \param ijk Parametric coordinates being evaluated
     */
    EntityHandle get_vertex( const HomCoord& ijk ) const;

    //! Get the vertex at the specified coordinates
    /**
     * \param i Parametric coordinates being evaluated
     * \param j Parametric coordinates being evaluated
     * \param k Parametric coordinates being evaluated
     */
    EntityHandle get_vertex( int i, int j = 0, int k = 0 ) const;

    //! Get parametric coordinates of the specified entity
    /** This function returns MB_ENTITY_NOT_FOUND if the entity is not
     * in this ScdBox.
     * \param ent Entity being queried
     * \param i Parametric coordinates returned
     * \param j Parametric coordinates returned
     * \param k Parametric coordinates returned
     * \param dir Parametric coordinate direction returned (in case of getting adjacent
     *            edges (2d, 3d) or faces (3d); not modified otherwise
     */
    ErrorCode get_params( EntityHandle ent, int& i, int& j, int& k, int& dir ) const;

    //! Get parametric coordinates of the specified entity, intermediate entities not allowed (no
    //! dir parameter)
    /** This function returns MB_ENTITY_NOT_FOUND if the entity is not
     * in this ScdBox, or MB_FAILURE if the entity is an intermediate-dimension entity.
     * \param ent Entity being queried
     * \param i Parametric coordinates returned
     * \param j Parametric coordinates returned
     * \param k Parametric coordinates returned
     */
    ErrorCode get_params( EntityHandle ent, int& i, int& j, int& k ) const;

    //! Get parametric coordinates of the specified entity
    /** This function returns MB_ENTITY_NOT_FOUND if the entity is not
     * in this ScdBox.
     * \param ent Entity being queried
     * \param ijkd Parametric coordinates returned (including direction, in case of
     *            getting adjacent edges (2d, 3d) or faces (3d))
     */
    ErrorCode get_params( EntityHandle ent, HomCoord& ijkd ) const;

    /** \brief Get the adjacent edge or face at a parametric location
     * This function gets the left (i=0), front (j=0), or bottom (k=0) edge or face for a parametric
     * element. Left, front, or bottom is indicated by dir = 0, 1, or 2, resp.  All edges and faces
     * in a structured mesh block can be accessed using these parameters. \param dim Dimension of
     * adjacent entity being requested \param i Parametric coordinates of cell being evaluated
     * \param j Parametric coordinates of cell being evaluated
     * \param k Parametric coordinates of cell being evaluated
     * \param dir Direction (0, 1, or 2), for getting adjacent edges (2d, 3d) or faces (3d)
     * \param ent Entity returned from this function
     * \param create_if_missing If true, creates the entity if it doesn't already exist
     */
    ErrorCode get_adj_edge_or_face( int dim, int i, int j, int k, int dir, EntityHandle& ent,
                                    bool create_if_missing = true ) const;

    //! Return whether the box contains the parameters passed in
    /**
     * \param i Parametric coordinates being evaluated
     * \param j Parametric coordinates being evaluated
     * \param k Parametric coordinates being evaluated
     */
    bool contains( int i, int j, int k ) const;

    //! Return whether the box contains the parameters passed in
    /**
     * \param i Parametric coordinates being evaluated
     * \param j Parametric coordinates being evaluated
     * \param k Parametric coordinates being evaluated
     */
    bool contains( const HomCoord& ijk ) const;

    //! Set/Get the entity set representing the box
    void box_set( EntityHandle this_set );
    EntityHandle box_set();

    //! Get coordinate arrays for vertex coordinates for a structured block
    /** Returns error if there isn't a single vertex sequence associated with this structured block
     * \param xc X coordinate array pointer returned
     * \param yc Y coordinate array pointer returned
     * \param zc Z coordinate array pointer returned
     */
    ErrorCode get_coordinate_arrays( double*& xc, double*& yc, double*& zc );

    //! Get read-only coordinate arrays for vertex coordinates for a structured block
    /** Returns error if there isn't a single vertex sequence associated with this structured block
     * \param xc X coordinate array pointer returned
     * \param yc Y coordinate array pointer returned
     * \param zc Z coordinate array pointer returned
     */
    ErrorCode get_coordinate_arrays( const double*& xc, const double*& yc, const double*& zc ) const;

    //! Return whether box is locally periodic in i
    /** Return whether box is locally periodic in i
     * \return True if box is locally periodic in i direction
     */
    bool locally_periodic_i() const;

    //! Return whether box is locally periodic in j
    /** Return whether box is locally periodic in j
     * \return True if box is locally periodic in j direction
     */
    bool locally_periodic_j() const;

    //! Return whether box is locally periodic in k
    /** Return whether box is locally periodic in k
     * \return True if box is locally periodic in k direction
     */
    bool locally_periodic_k() const;

    //! Set local periodicity
    /**
     * \param lperiodic Vector of ijk periodicities to set this box to
     */
    void locally_periodic( bool lperiodic[3] );

    //! Get local periodicity
    /**
     * \return Vector of ijk periodicities for this box
     */
    const int* locally_periodic() const;

    //! Return parallel data
    /** Return parallel data, if there is any
     * \return par_data Parallel data set on this box
     */
    ScdParData& par_data()
    {
        return parData;
    }

    //! Return parallel data
    /** Return parallel data, if there is any
     * \return par_data Parallel data set on this box
     */
    const ScdParData& par_data() const
    {
        return parData;
    }

    //! set parallel data
    /** Set parallel data for this box
     * \param par_data Parallel data to be set on this box
     */
    void par_data( const ScdParData& par_datap )
    {
        parData = par_datap;
    }

  private:
    //! Constructor
    /** Create a structured box instance; this constructor is private because it should only be
     * called from ScdInterface, a friend class.  This constructor takes two sequences, one of which
     * can be NULL.  If both sequences come in non-NULL, the first should be a VertexSequence*
     * corresponding to a structured vertex sequence and the second should be a
     * StructuredElementSeq*.  If the 2nd is NULL, the first can be either of those types.  The
     * other members of this class are taken from the sequences (e.g. parametric space) or the box
     * set argument.  Tags on the box set should be set from the caller. \param sc_impl A
     * ScdInterface instance \param box_set Entity set representing this rectangle \param seq1 An
     * EntitySequence (see ScdBox description) \param seq2 An EntitySequence (see ScdBox
     * description), or NULL
     */
    ScdBox( ScdInterface* sc_impl, EntityHandle box_set, EntitySequence* seq1, EntitySequence* seq2 = NULL );

    //! function to get vertex handle directly from sequence
    /** \param i Parameter being queried
     * \param j Parameter being queried
     * \param k Parameter being queried
     */
    EntityHandle get_vertex_from_seq( int i, int j, int k ) const;

    //! set the vertex sequence
    ErrorCode vert_dat( ScdVertexData* vert_dat );

    //! get the vertex sequence
    ScdVertexData* vert_dat() const;

    //! set the element sequence
    ErrorCode elem_seq( EntitySequence* elem_seq );

    //! get the element sequence
    StructuredElementSeq* elem_seq() const;

    //! Set the starting vertex handle for this box
    void start_vertex( EntityHandle startv );

    //! Set the starting entity handle for this box
    void start_element( EntityHandle starte );

    //! interface instance
    ScdInterface* scImpl;

    //! entity set representing this box
    EntityHandle boxSet;

    //! vertex sequence this box represents, if there's only one, otherwise they're
    //! retrieved from the element sequence
    ScdVertexData* vertDat;

    //! element sequence this box represents
    StructuredElementSeq* elemSeq;

    //! starting vertex handle for this box
    EntityHandle startVertex;

    //! starting element handle for this box
    EntityHandle startElem;

    //! lower and upper corners
    int boxDims[6];

    //! is locally periodic in i or j or k
    int locallyPeriodic[3];

    //! parallel data associated with this box, if any
    ScdParData parData;

    //! parameter extents
    HomCoord boxSize;

    //! convenience parameters, (boxSize[1]-1)*(boxSize[0]-1) and boxSize[0]-1
    int boxSizeIJ;
    int boxSizeIJM1;
    int boxSizeIM1;
};

inline ErrorCode ScdInterface::compute_partition( int np, int nr, const ScdParData& par_data, int* ldims,
                                                  int* lperiodic, int* pdims )
{
    ErrorCode rval = MB_SUCCESS;
    switch( par_data.partMethod )
    {
        case ScdParData::ALLJORKORI:
        case -1:
            rval = compute_partition_alljorkori( np, nr, par_data.gDims, par_data.gPeriodic, ldims, lperiodic, pdims );
            break;
        case ScdParData::ALLJKBAL:
            rval = compute_partition_alljkbal( np, nr, par_data.gDims, par_data.gPeriodic, ldims, lperiodic, pdims );
            break;
        case ScdParData::SQIJ:
            rval = compute_partition_sqij( np, nr, par_data.gDims, par_data.gPeriodic, ldims, lperiodic, pdims );
            break;
        case ScdParData::SQJK:
            rval = compute_partition_sqjk( np, nr, par_data.gDims, par_data.gPeriodic, ldims, lperiodic, pdims );
            break;
        case ScdParData::SQIJK:
            rval = compute_partition_sqijk( np, nr, par_data.gDims, par_data.gPeriodic, ldims, lperiodic, pdims );
            break;
        default:
            rval = MB_FAILURE;
            break;
    }

    return rval;
}

inline ErrorCode ScdInterface::compute_partition_alljorkori( int np, int nr, const int gijk[6],
                                                             const int* const gperiodic, int* ldims, int* lperiodic,
                                                             int* pijk )
{
    // partition *the elements* over the parametric space; 1d partition for now, in the j, k, or i
    // parameters
    int tmp_lp[3], tmp_pijk[3];
    if( !lperiodic ) lperiodic = tmp_lp;
    if( !pijk ) pijk = tmp_pijk;

    for( int i = 0; i < 3; i++ )
        lperiodic[i] = gperiodic[i];

    if( np == 1 )
    {
        if( ldims )
        {
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            ldims[1] = gijk[1];
            ldims[4] = gijk[4];
            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
        }
        pijk[0] = pijk[1] = pijk[2] = 1;
    }
    else
    {
        if( gijk[4] - gijk[1] > np )
        {
            // partition j over procs
            int dj    = ( gijk[4] - gijk[1] ) / np;
            int extra = ( gijk[4] - gijk[1] ) % np;
            ldims[1]  = gijk[1] + nr * dj + std::min( nr, extra );
            ldims[4]  = ldims[1] + dj + ( nr < extra ? 1 : 0 );

            if( gperiodic[1] && np > 1 )
            {
                lperiodic[1] = 0;
                ldims[4]++;
            }

            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            pijk[0] = pijk[2] = 1;
            pijk[1]           = np;
        }
        else if( gijk[5] - gijk[2] > np )
        {
            // partition k over procs
            int dk    = ( gijk[5] - gijk[2] ) / np;
            int extra = ( gijk[5] - gijk[2] ) % np;
            ldims[2]  = gijk[2] + nr * dk + std::min( nr, extra );
            ldims[5]  = ldims[2] + dk + ( nr < extra ? 1 : 0 );

            ldims[1] = gijk[1];
            ldims[4] = gijk[4];
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            pijk[0] = pijk[1] = 1;
            pijk[2]           = np;
        }
        else if( gijk[3] - gijk[0] > np )
        {
            // partition i over procs
            int di    = ( gijk[3] - gijk[0] ) / np;
            int extra = ( gijk[3] - gijk[0] ) % np;
            ldims[0]  = gijk[0] + nr * di + std::min( nr, extra );
            ldims[3]  = ldims[0] + di + ( nr < extra ? 1 : 0 );

            if( gperiodic[0] && np > 1 )
            {
                lperiodic[0] = 0;
                ldims[3]++;
            }

            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
            ldims[1] = gijk[1];
            ldims[4] = gijk[4];

            pijk[1] = pijk[2] = 1;
            pijk[0]           = np;
        }
        else
        {
            // Couldn't find a suitable partition...
            return MB_FAILURE;
        }
    }

    return MB_SUCCESS;
}

inline ErrorCode ScdInterface::compute_partition_alljkbal( int np, int nr, const int gijk[6],
                                                           const int* const gperiodic, int* ldims, int* lperiodic,
                                                           int* pijk )
{
    int tmp_lp[3], tmp_pijk[3];
    if( !lperiodic ) lperiodic = tmp_lp;
    if( !pijk ) pijk = tmp_pijk;

    for( int i = 0; i < 3; i++ )
        lperiodic[i] = gperiodic[i];

    if( np == 1 )
    {
        if( ldims )
        {
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            ldims[1] = gijk[1];
            ldims[4] = gijk[4];
            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
        }
        pijk[0] = pijk[1] = pijk[2] = 1;
    }
    else
    {
        // improved, possibly 2-d partition
        std::vector< double > kfactors;
        kfactors.push_back( 1 );
        int K = gijk[5] - gijk[2];
        for( int i = 2; i < K; i++ )
            if( !( K % i ) && !( np % i ) ) kfactors.push_back( i );
        kfactors.push_back( K );

        // compute the ideal nj and nk
        int J          = gijk[4] - gijk[1];
        double njideal = sqrt( ( (double)( np * J ) ) / ( (double)K ) );
        double nkideal = ( njideal * K ) / J;

        int nk, nj;
        if( nkideal < 1.0 )
        {
            nk = 1;
            nj = np;
        }
        else
        {
            std::vector< double >::iterator vit = std::lower_bound( kfactors.begin(), kfactors.end(), nkideal );
            if( vit == kfactors.begin() )
                nk = 1;
            else
                nk = (int)*( --vit );
            nj = np / nk;
        }

        int dk = K / nk;
        int dj = J / nj;

        ldims[2] = gijk[2] + ( nr % nk ) * dk;
        ldims[5] = ldims[2] + dk;

        int extra = J % nj;

        ldims[1] = gijk[1] + ( nr / nk ) * dj + std::min( nr / nk, extra );
        ldims[4] = ldims[1] + dj + ( nr / nk < extra ? 1 : 0 );

        ldims[0] = gijk[0];
        ldims[3] = gijk[3];

        if( gperiodic[1] && np > 1 )
        {
            lperiodic[1] = 0;
            if( nr / nk == nj - 1 ) { ldims[1]++; }
        }

        pijk[0] = 1;
        pijk[1] = nj;
        pijk[2] = nk;
    }

    return MB_SUCCESS;
}

inline ErrorCode ScdInterface::compute_partition_sqij( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                       int* ldims, int* lperiodic, int* pijk )
{
    int tmp_lp[3], tmp_pijk[3];
    if( !lperiodic ) lperiodic = tmp_lp;
    if( !pijk ) pijk = tmp_pijk;

    // square IxJ partition

    for( int i = 0; i < 3; i++ )
        lperiodic[i] = gperiodic[i];

    if( np == 1 )
    {
        if( ldims )
        {
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            ldims[1] = gijk[1];
            ldims[4] = gijk[4];
            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
        }
        pijk[0] = pijk[1] = pijk[2] = 1;
    }
    else
    {
        std::vector< double > pfactors, ppfactors;
        for( int i = 2; i <= np / 2; i++ )
            if( !( np % i ) )
            {
                pfactors.push_back( i );
                ppfactors.push_back( ( (double)( i * i ) ) / np );
            }
        pfactors.push_back( np );
        ppfactors.push_back( (double)np );

        // ideally, Px/Py = I/J
        double ijratio = ( (double)( gijk[3] - gijk[0] ) ) / ( (double)( gijk[4] - gijk[1] ) );

        unsigned int ind                        = 0;
        std::vector< double >::iterator optimal = std::lower_bound( ppfactors.begin(), ppfactors.end(), ijratio );
        if( optimal == ppfactors.end() ) { ind = ppfactors.size() - 1; }
        else
        {
            ind = optimal - ppfactors.begin();
            if( ind && fabs( ppfactors[ind - 1] - ijratio ) < fabs( ppfactors[ind] - ijratio ) ) ind--;
        }

        // VARIABLES DESCRIBING THE MESH:
        // pi, pj = # procs in i and j directions
        // nri, nrj = my proc's position in i, j directions
        // I, J = # edges/elements in i, j directions
        // iextra, jextra = # procs having extra edge in i/j direction
        // top_i, top_j = if true, I'm the last proc in the i/j direction
        // i, j = # edges locally in i/j direction, *not* including one for iextra/jextra
        int pi = pfactors[ind];
        int pj = np / pi;

        int I = ( gijk[3] - gijk[0] ), J = ( gijk[4] - gijk[1] );
        int iextra = I % pi, jextra = J % pj, i = I / pi, j = J / pj;
        int nri = nr % pi, nrj = nr / pi;

        if( ldims )
        {
            ldims[0] = gijk[0] + i * nri + std::min( iextra, nri );
            ldims[3] = ldims[0] + i + ( nri < iextra ? 1 : 0 );
            ldims[1] = gijk[1] + j * nrj + std::min( jextra, nrj );
            ldims[4] = ldims[1] + j + ( nrj < jextra ? 1 : 0 );

            ldims[2] = gijk[2];
            ldims[5] = gijk[5];

            if( gperiodic[0] && pi > 1 )
            {
                lperiodic[0] = 0;
                if( nri == pi - 1 ) ldims[3]++;
            }
            if( gperiodic[1] && pj > 1 )
            {
                lperiodic[1] = 0;
                if( nrj == pj - 1 ) ldims[4]++;
            }
        }

        pijk[0] = pi;
        pijk[1] = pj;
        pijk[2] = 1;
    }

    return MB_SUCCESS;
}

inline ErrorCode ScdInterface::compute_partition_sqjk( int np, int nr, const int gijk[6], const int* const gperiodic,
                                                       int* ldims, int* lperiodic, int* pijk )
{
    int tmp_lp[3], tmp_pijk[3];
    if( !lperiodic ) lperiodic = tmp_lp;
    if( !pijk ) pijk = tmp_pijk;

    // square JxK partition
    for( int i = 0; i < 3; i++ )
        lperiodic[i] = gperiodic[i];

    if( np == 1 )
    {
        if( ldims )
        {
            ldims[0] = gijk[0];
            ldims[3] = gijk[3];
            ldims[1] = gijk[1];
            ldims[4] = gijk[4];
            ldims[2] = gijk[2];
            ldims[5] = gijk[5];
        }
        pijk[0] = pijk[1] = pijk[2] = 1;
    }
    else
    {
        std::vector< double > pfactors, ppfactors;
        for( int p = 2; p <= np; p++ )
            if( !( np % p ) )
            {
                pfactors.push_back( p );
                ppfactors.push_back( ( (double)( p * p ) ) / np );
            }

        // ideally, Pj/Pk = J/K
        int pj, pk;
        if( gijk[5] == gijk[2] )
        {
            pk = 1;
            pj = np;
        }
        else
        {
            double jkratio = ( (double)( gijk[4] - gijk[1] ) ) / ( (double)( gijk[5] - gijk[2] ) );

            std::vector< double >::iterator vit = std::lower_bound( ppfactors.begin(), ppfactors.end(), jkratio );
            if( vit == ppfactors.end() )
                --vit;
            else if( vit != ppfactors.begin() && fabs( *( vit - 1 ) - jkratio ) < fabs( ( *vit ) - jkratio ) )
                --vit;
            int ind = vit - ppfactors.begin();

            pj = 1;
            if( ind >= 0 && !pfactors.empty() ) pfactors[ind];
            pk = np / pj;
        }

        int K = ( gijk[5] - gijk[2] ), J = ( gijk[4] - gijk[1] );
        int jextra = J % pj, kextra = K % pk, j = J / pj, k = K / pk;
        int nrj = nr % pj, nrk = nr / pj;
        ldims[1] = gijk[1] + j * nrj + std::min( jextra, nrj );
        ldims[4] = ldims[1] + j + ( nrj < jextra ? 1 : 0 );
        ldims[2] = gijk[2] + k * nrk + std::min( kextra, nrk );
        ldims[5] = ldims[2] + k + ( nrk < kextra ? 1 : 0 );

        ldims[0] = gijk[0];
        ldims[3] = gijk[3];

        if( gperiodic[1] && pj > 1 )
        {
            lperiodic[1] = 0;
            if( nrj == pj - 1 ) ldims[4]++;
        }

        pijk[0] = 1;
        pijk[1] = pj;
        pijk[2] = pk;
    }

    return MB_SUCCESS;
}

inline ErrorCode ScdInterface::compute_partition_sqijk( int np, int nr, const int* const gijk,
                                                        const int* const gperiodic, int* ldims, int* lperiodic,
                                                        int* pijk )
{
    if( gperiodic[0] || gperiodic[1] || gperiodic[2] ) return MB_FAILURE;

    int tmp_lp[3], tmp_pijk[3];
    if( !lperiodic ) lperiodic = tmp_lp;
    if( !pijk ) pijk = tmp_pijk;

    // square IxJxK partition

    for( int i = 0; i < 3; i++ )
        lperiodic[i] = gperiodic[i];

    if( np == 1 )
    {
        if( ldims )
            for( int i = 0; i < 6; i++ )
                ldims[i] = gijk[i];
        pijk[0] = pijk[1] = pijk[2] = 1;
        return MB_SUCCESS;
    }

    std::vector< int > pfactors;
    pfactors.push_back( 1 );
    for( int i = 2; i <= np / 2; i++ )
        if( !( np % i ) ) pfactors.push_back( i );
    pfactors.push_back( np );

    // test for IJ, JK, IK
    int IJK[3], dIJK[3];
    for( int i = 0; i < 3; i++ )
        IJK[i] = std::max( gijk[3 + i] - gijk[i], 1 );
    // order IJK from lo to hi
    int lo = 0, hi = 0;
    for( int i = 1; i < 3; i++ )
    {
        if( IJK[i] < IJK[lo] ) lo = i;
        if( IJK[i] > IJK[hi] ) hi = i;
    }
    if( lo == hi ) hi = ( lo + 1 ) % 3;
    int mid = 3 - lo - hi;
    // search for perfect subdivision of np that balances #cells
    int perfa_best = -1, perfb_best = -1;
    double ratio = 0.0;
    for( int po = 0; po < (int)pfactors.size(); po++ )
    {
        for( int pi = po; pi < (int)pfactors.size() && np / ( pfactors[po] * pfactors[pi] ) >= pfactors[pi]; pi++ )
        {
            int p3 =
                std::find( pfactors.begin(), pfactors.end(), np / ( pfactors[po] * pfactors[pi] ) ) - pfactors.begin();
            if( p3 == (int)pfactors.size() || pfactors[po] * pfactors[pi] * pfactors[p3] != np )
                continue;  // po*pi should exactly factor np
            assert( po <= pi && pi <= p3 );
            // by definition, po <= pi <= p3
            double minl =
                       std::min( std::min( IJK[lo] / pfactors[po], IJK[mid] / pfactors[pi] ), IJK[hi] / pfactors[p3] ),
                   maxl =
                       std::max( std::max( IJK[lo] / pfactors[po], IJK[mid] / pfactors[pi] ), IJK[hi] / pfactors[p3] );
            if( minl / maxl > ratio )
            {
                ratio      = minl / maxl;
                perfa_best = po;
                perfb_best = pi;
            }
        }
    }
    if( perfa_best == -1 || perfb_best == -1 ) return MB_FAILURE;

    // VARIABLES DESCRIBING THE MESH:
    // pijk[i] = # procs in direction i
    // numr[i] = my proc's position in direction i
    // dIJK[i] = # edges/elements in direction i
    // extra[i]= # procs having extra edge in direction i
    // top[i] = if true, I'm the last proc in direction i

    pijk[lo]     = pfactors[perfa_best];
    pijk[mid]    = pfactors[perfb_best];
    pijk[hi]     = ( np / ( pfactors[perfa_best] * pfactors[perfb_best] ) );
    int extra[3] = { 0, 0, 0 }, numr[3];
    for( int i = 0; i < 3; i++ )
    {
        dIJK[i]  = IJK[i] / pijk[i];
        extra[i] = IJK[i] % pijk[i];
    }
    numr[2] = nr / ( pijk[0] * pijk[1] );
    int rem = nr % ( pijk[0] * pijk[1] );
    numr[1] = rem / pijk[0];
    numr[0] = rem % pijk[0];
    for( int i = 0; i < 3; i++ )
    {
        extra[i]     = IJK[i] % dIJK[i];
        ldims[i]     = gijk[i] + numr[i] * dIJK[i] + std::min( extra[i], numr[i] );
        ldims[3 + i] = ldims[i] + dIJK[i] + ( numr[i] < extra[i] ? 1 : 0 );
    }

    return MB_SUCCESS;
}

inline int ScdInterface::gtol( const int* gijk, int i, int j, int k )
{
    return ( ( k - gijk[2] ) * ( gijk[3] - gijk[0] + 1 ) * ( gijk[4] - gijk[1] + 1 ) +
             ( j - gijk[1] ) * ( gijk[3] - gijk[0] + 1 ) + i - gijk[0] );
}

inline ErrorCode ScdInterface::get_indices( const int* const ldims, const int* const rdims, const int* const across_bdy,
                                            int* face_dims, std::vector< int >& shared_indices )
{
    // check for going across periodic bdy and face_dims not in my ldims (I'll always be on top in
    // that case)...
    if( across_bdy[0] > 0 && face_dims[0] != ldims[3] )
        face_dims[0] = face_dims[3] = ldims[3];
    else if( across_bdy[0] < 0 && face_dims[0] != ldims[0] )
        face_dims[0] = face_dims[3] = ldims[0];
    if( across_bdy[1] > 0 && face_dims[1] != ldims[4] )
        face_dims[1] = face_dims[4] = ldims[4];
    else if( across_bdy[1] < 0 && face_dims[1] != ldims[1] )
        face_dims[0] = face_dims[3] = ldims[1];

    for( int k = face_dims[2]; k <= face_dims[5]; k++ )
        for( int j = face_dims[1]; j <= face_dims[4]; j++ )
            for( int i = face_dims[0]; i <= face_dims[3]; i++ )
                shared_indices.push_back( gtol( ldims, i, j, k ) );

    if( across_bdy[0] > 0 && face_dims[0] != rdims[0] )
        face_dims[0] = face_dims[3] = rdims[0];
    else if( across_bdy[0] < 0 && face_dims[0] != rdims[3] )
        face_dims[0] = face_dims[3] = rdims[3];
    if( across_bdy[1] > 0 && face_dims[1] != rdims[1] )
        face_dims[1] = face_dims[4] = rdims[1];
    else if( across_bdy[1] < 0 && face_dims[1] != rdims[4] )
        face_dims[0] = face_dims[3] = rdims[4];

    for( int k = face_dims[2]; k <= face_dims[5]; k++ )
        for( int j = face_dims[1]; j <= face_dims[4]; j++ )
            for( int i = face_dims[0]; i <= face_dims[3]; i++ )
                shared_indices.push_back( gtol( rdims, i, j, k ) );

    return MB_SUCCESS;
}

inline ErrorCode ScdInterface::get_neighbor( int np, int pfrom, const ScdParData& spd, const int* const dijk, int& pto,
                                             int* rdims, int* facedims, int* across_bdy )
{
    if( !dijk[0] && !dijk[1] && !dijk[2] )
    {
        // not going anywhere, return
        pto = -1;
        return MB_SUCCESS;
    }

    switch( spd.partMethod )
    {
        case ScdParData::ALLJORKORI:
        case -1:
            return get_neighbor_alljorkori( np, pfrom, spd.gDims, spd.gPeriodic, dijk, pto, rdims, facedims,
                                            across_bdy );
        case ScdParData::ALLJKBAL:
            return get_neighbor_alljkbal( np, pfrom, spd.gDims, spd.gPeriodic, dijk, pto, rdims, facedims, across_bdy );
        case ScdParData::SQIJ:
            return get_neighbor_sqij( np, pfrom, spd.gDims, spd.gPeriodic, dijk, pto, rdims, facedims, across_bdy );
        case ScdParData::SQJK:
            return get_neighbor_sqjk( np, pfrom, spd.gDims, spd.gPeriodic, dijk, pto, rdims, facedims, across_bdy );
        case ScdParData::SQIJK:
            return get_neighbor_sqijk( np, pfrom, spd.gDims, spd.gPeriodic, dijk, pto, rdims, facedims, across_bdy );
        default:
            break;
    }

    return MB_FAILURE;
}

inline ErrorCode ScdInterface::tag_shared_vertices( ParallelComm* pcomm, EntityHandle seth )
{
    ScdBox* box = get_scd_box( seth );
    if( !box )
    {
        // look for contained boxes
        Range tmp_range;
        ErrorCode rval = mbImpl->get_entities_by_type( seth, MBENTITYSET, tmp_range );
        if( MB_SUCCESS != rval ) return rval;
        for( Range::iterator rit = tmp_range.begin(); rit != tmp_range.end(); ++rit )
        {
            box = get_scd_box( *rit );
            if( box ) break;
        }
    }

    if( !box ) return MB_FAILURE;

    return tag_shared_vertices( pcomm, box );
}

inline ScdInterface* ScdBox::sc_impl() const
{
    return scImpl;
}

inline EntityHandle ScdBox::start_vertex() const
{
    return startVertex;
}

inline void ScdBox::start_vertex( EntityHandle startv )
{
    startVertex = startv;
}

inline EntityHandle ScdBox::start_element() const
{
    return startElem;
}

inline void ScdBox::start_element( EntityHandle starte )
{
    startElem = starte;
}

inline int ScdBox::num_elements() const
{
    if( !startElem ) return 0;  // not initialized yet

    /* for a structured mesh, total number of elements is obtained by multiplying
        number of elements in each direction
      number of elements in each direction is given by number of vertices in that direction minus 1
      if periodic in that direction, the last vertex is the same as first one, count one more
      element
      */
    int num_e_i = ( -1 == boxSize[0] || 1 == boxSize[0] ) ? 1 : boxSize[0] - 1;
    if( locallyPeriodic[0] ) ++num_e_i;

    int num_e_j = ( -1 == boxSize[1] || 1 == boxSize[1] ) ? 1 : boxSize[1] - 1;
    if( locallyPeriodic[1] ) ++num_e_j;

    int num_e_k = ( -1 == boxSize[2] || 1 == boxSize[2] ) ? 1 : boxSize[2] - 1;
    if( locallyPeriodic[2] ) ++num_e_k;

    return num_e_i * num_e_j * num_e_k;
}

inline int ScdBox::num_vertices() const
{
    return boxSize[0] * ( !boxSize[1] ? 1 : boxSize[1] ) * ( !boxSize[2] ? 1 : boxSize[2] );
}

inline const int* ScdBox::box_dims() const
{
    return boxDims;
}

inline HomCoord ScdBox::box_min() const
{
    return HomCoord( boxDims, 3 );
}

inline HomCoord ScdBox::box_max() const
{
    return HomCoord( boxDims + 3, 3 );
}

inline HomCoord ScdBox::box_size() const
{
    return boxSize;
}

inline void ScdBox::box_size( int* ijk ) const
{
    ijk[0] = boxSize[0];
    ijk[1] = boxSize[1];
    ijk[2] = boxSize[2];
}

inline void ScdBox::box_size( int& i, int& j, int& k ) const
{
    i = boxSize[0];
    j = boxSize[1];
    k = boxSize[2];
}

inline EntityHandle ScdBox::get_element( int i, int j, int k ) const
{
    return ( !startElem
                 ? 0
                 : startElem + ( k - boxDims[2] ) * boxSizeIJM1 + ( j - boxDims[1] ) * boxSizeIM1 + i - boxDims[0] );
}

inline EntityHandle ScdBox::get_element( const HomCoord& ijk ) const
{
    return get_element( ijk[0], ijk[1], ijk[2] );
}

inline EntityHandle ScdBox::get_vertex( int i, int j, int k ) const
{
    return ( vertDat
                 ? startVertex + ( boxDims[2] == -1 && boxDims[5] == -1 ? 0 : ( k - boxDims[2] ) ) * boxSizeIJ +
                       ( boxDims[1] == -1 && boxDims[4] == -1 ? 0 : ( j - boxDims[1] ) ) * boxSize[0] + i - boxDims[0]
                 : get_vertex_from_seq( i, j, k ) );
}

inline EntityHandle ScdBox::get_vertex( const HomCoord& ijk ) const
{
    return get_vertex( ijk[0], ijk[1], ijk[2] );
}

inline bool ScdBox::contains( const HomCoord& ijk ) const
{
    return ( ijk >= HomCoord( boxDims, 3 ) && ijk <= HomCoord( boxDims + 3, 3 ) );
}

inline bool ScdBox::contains( int i, int j, int k ) const
{
    return contains( HomCoord( i, j, k ) );
}

inline void ScdBox::box_set( EntityHandle this_set )
{
    boxSet = this_set;
}

inline EntityHandle ScdBox::box_set()
{
    return boxSet;
}

inline ScdVertexData* ScdBox::vert_dat() const
{
    return vertDat;
}

inline StructuredElementSeq* ScdBox::elem_seq() const
{
    return elemSeq;
}

inline ErrorCode ScdBox::get_params( EntityHandle ent, int& i, int& j, int& k, int& dir ) const
{
    HomCoord hc;
    ErrorCode rval = get_params( ent, hc );
    if( MB_SUCCESS == rval )
    {
        i   = hc[0];
        j   = hc[1];
        k   = hc[2];
        dir = hc[3];
    }

    return rval;
}

inline ErrorCode ScdBox::get_params( EntityHandle ent, int& i, int& j, int& k ) const
{
    HomCoord hc;
    ErrorCode rval = get_params( ent, hc );
    if( MB_SUCCESS == rval )
    {
        i = hc[0];
        j = hc[1];
        k = hc[2];
    }

    return rval;
}

inline bool ScdBox::locally_periodic_i() const
{
    return locallyPeriodic[0];
}

inline bool ScdBox::locally_periodic_j() const
{
    return locallyPeriodic[1];
}

inline bool ScdBox::locally_periodic_k() const
{
    return locallyPeriodic[2];
}

inline void ScdBox::locally_periodic( bool lperiodic[3] )
{
    for( int i = 0; i < 3; i++ )
        locallyPeriodic[i] = lperiodic[i];
}

inline const int* ScdBox::locally_periodic() const
{
    return locallyPeriodic;
}

std::ostream& operator<<( std::ostream& str, const ScdParData& pd );

}  // namespace moab
#endif