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libMeshb helper functions

The source file libMeshb7_helpers.c is a collection additional functions that you may include in your code. These functions are of higher level than the libMeshb which is a low level I/O library. Consequently, they may not be of interest to everyone and are not part of the library itself.

This higher-level code offers some data structures that store multiple fields (files, tables, information) as well as a high-level procedure to perform on these structures (open, allocate and read a whole mesh file with a single call for example).

You can either include the C file in your project or pick-up some functions and structures that suit your needs.

Define the size of your integers and real numbers

Two data kinds are defined to easily switch from 32-bit and 64-bit integers and reals. This convention is used throughout the helper procedures.

itg should be used to define all integers instead of using int or long, its default size is 32 bits (int32_t) and you only need to add the compiling flag -DINT64 to switch all itg to 64-bit (int64_t).

fpn should be used to define all reals instead of using float or double, its default size is 64 bits (double) and you only need to add the compiling flag -DREAL32 to switch all itg to 32-bit (float).

Polyhedral mesh structure

To easily handle arbitrary degree polygons and polyhedra, a new set of keywords have been added:

  • GmfBoundaryPolygonHeaders
  • GmfBoundaryPolygonVertices
  • GmfInnerPolygonHeaders
  • GmfInnerPolygonVertices
  • GmfPolyhedraHeaders
  • GmfPolyhedraFaces

All the tables pointers and sizes can be conveniently stored in this dedicated structure.

typedef struct
{
   int64_t  MshIdx;
   itg      NmbBndHdr, (*BndHdrTab)[2], NmbBndVer, *BndVerTab;
   itg      NmbInrHdr, (*InrHdrTab)[2], NmbInrVer, *InrVerTab;
   itg      NmbVolHdr, (*VolHdrTab)[2], NmbVolFac, *VolFacTab;
}PolMshSct;

  • MshIdx stores the mesh file index this structure if associated with.

  • NmbBndHdr: number of lines in the GmfBoundaryPolygonHeaders keyword (number of boundary polygons).

  • BndHdrTab: table of polygon headers that give the index of the polygon's vertices table in BndVerTab and a material reference.

  • NmbBndVer: total size of compounded boundary polygons vertices (GmfBoundaryPolygonVertices).

  • BndVerTab: table of vertex indices of all boundary polygons.

  • NmbInrHdr: number of lines in the GmfInnerPolygonHeaders keyword (number of inner polygons referenced by polyhedra).

  • InrHdrTab: table of polygon headers that give the index of the polygon's vertices table in InrVerTab and a material reference.

  • NmbInrVer: total size of compounded inner polygons vertices (GmfInnerPolygonVertices).

  • InrVerTab: table of vertex indices of all inner polygons.

  • NmbVolHdr: number of lines in the GmfPolyhedraHeaders keyword (number of polyhedra).

  • VolHdrTab: table of polyhedra headers that give the index of the element face index table in VolFacTab and a material reference.

  • NmbVolFac: total size of compounded polyhedra faces (GmfPolyhedraFaces).

  • VolFacTab: table of polygons indices of all polyhedra.

GmfAllocatePolyghedralStructure

Synopsis: this function only allocate memories but does not read the data from the mesh file.

  • input: the index of an already opened mesh file that contains polygons or polyhedra.
  • output: a PolMshSct structure set up with the table sizes and pointers to allocated memory.

GmfFreePolyghedralStructure

Synopsis: free all tables and the structure itself.

  • input: a pointer to an allocated PolMshSct structure.

GmfReadBoundaryPolygons

Synopsis: reads the two keywords' fields, GmfBoundaryPolygonHeaders and GmfBoundaryPolygonVertices, into the polyhedra structure's tables.

  • input: a pointer to an allocated PolMshSct structure.
  • output: 0 in case of failure and 1 otherwise.

GmfReadPolyhedra

Synopsis: reads the four keywords' fields, GmfInnerPolygonHeaders, GmfInnerPolygonVertices, GmfPolyhedraHeaders and GmfPolyhedraFaces, into the polyhedra structure's tables.

  • input: a pointer to an allocated PolMshSct structure.
  • output: 0 in case of failure and 1 otherwise.

GmfGetBoundaryPolygon

Synopsis: extract a polygon's vertex list from the main global table and copy them to your local table.

  • input: a pointer to an allocated PolMshSct structure, the index of a boundary polygonal face, a pointer to a table of itg that you have previously allocated with at least 256 entries.
  • output: the polygon's number of vertices is the function's returned value (0 in case of failure) and the provided table is filled with the polygons' vertex indices.

GmfGetInnerPolygon

Same procedure as above but for inner polygons only.

GmfGetPolyhedron

Synopsis: extract a polyhedron's face list from the main global table and copy them to your local table.

  • input: a pointer to an allocated PolMshSct structure, the index of a polyhedral element, a pointer to a table of itg that you have previously allocated with at least 256 entries.
  • output: the polyhedron's number of faces is the function's returned value (0 in case of failure) and the provided table is filled with the polyhedron's face indices.