The methods described in section \ref mesh do not take into account information about
\c polygonal and \c polyhedral cells contained in a MESH object.
-Indeed, in the MEDMEM library, the connectivity data
-for these elements are stored separately . Therefore,
-the methods that give access to this data are slightly different from
-those of section \ref mesh.
+Indeed, in the MEDMEM library, the connectivity data for these
+elements are stored the same way as connectivity of standard
+elements. Therefore, the methods that give access to this data are
+same as those of section \ref mesh.
-Also, the polygon and the polyhedra case differ in nature,
+The polygon and the polyhedra case differ in nature,
because in 3D, the list of nodes is not sufficient
to described the shape of an element. A descending
cell>face>nodes connectivity has to be established
\image latex polygon_connectivity_small.eps "Example for polygon connectivity"
-- The standard element connectivity table writes : {2, 6, 7, 3, 3, 7, 8, 4 }
-- The standard element connectivity index table writes : {1, 5, 9 }
-- The polygon element connectivity table writes : {1, 2, 3, 4, 5 }
-- The polygon element connectivity index table writes : {1, 6 }
+- The connectivity table writes : {2, 6, 7, 3, 3, 7, 8, 4, 1, 2, 3, 4, 5 }
+- The connectivity index table writes : {1, 5, 9, 14 }
\section polyhedron_conn Polyhedron connectivity
For polyhedra, in the nodal connectivity case,
-one more array is required, because a
-list of nodes does not suffice to describe a general polyhedron.
-A general polyhedron is therefore described by a list of faces,
-each of those being described by a list of nodes.
+list of nodes does not suffice to describe a general polyhedron;
+information of connectivity of each face is needed.
+A general polyhedron is therefore described by a list of nodes of
+all faces with -1 as separator between faces.
Let us consider an example with the two tetrahedra represented on
figure \ref fig_polyhedron_connectivity , the left one
\image html polyhedron_connectivity_small.png "Example for polyhedron connectivity. Node numbers are written with a normal font, while face numbers are written in italic font."
\image latex polyhedron_connectivity_small.eps "Example for polyhedron connectivity. Node numbers are written with a normal font, while face numbers are written in italic font."
-- The standard element index connectivity table writes : {1, 5 }
-- The standard element connectivity table writes : {1, 2, 3, 4 }
-- The polyhedra face connectivity index table writes :{1, 5}
-- The polyhedra connectivity index table writes : {1, 4, 7, 10, 13}
-- The polyhedra connectivity (face/node connectivity) table writes : {2, 3, 5, 2, 4, 5, 4, 5, 3, 2, 3, 4}
-
-Note that as they are not needed as such, the face numberings are not stored
-in any array. Only the number of nodes per face is implicitly stored
-in the polyhedra face connectivity index table.
+- The connectivity table writes : {1, 2, 3, 4, 2, 5, 3, -1, 2, 4, 5, -1, 4, 3, 5, -1, 2, 3, 4}
+- The index connectivity table writes : {1, 5, 20 }
If there are two \c MED_POLYHEDRA elements that share a common face,
the list of nodes is repeated twice in the polyhedron connectivity
-array.
-
-\section poly_outline Outline
-The methods associated to polygons/polyhedra are located in the following classes :
-- access methods are stored in MESH : \ref MESH_poly
-- creation methods are in MESHING : \ref MESHING_poly
+array but with reversed order.
\section poly_example Example
The following example illustrates the creation method for a mesh that
contains polygons and/or polyhedra :
\include test_MEDMEM_MeshingPoly.cxx
-*/
\ No newline at end of file
+*/
