Table 6.180—DRM_Mesh_Face_Table

Property

Description

Superclass

· <DRM Data Table>

Class

· <DRM Mesh Face Table>

Subclass

· none

Definition

A two-dimensional <DRM Data Table> which defines the face elements of a <DRM Finite Element Mesh> instance in terms of vertex numbers in the ordered <DRM Vertex> component list of the <DRM Finite Element Mesh> and, optionally, the topology of the face elements. The size of the first dimension is provided in the field value total_mesh_faces while the size of the second dimension is provided in the field value max_node_and_rings.

The first data element specifies, for cell i, j, the index in the ordered <DRM Vertex> list of the <DRM Vertex> representing the jth node of the ith mesh face. If the ith mesh face contains less than j nodes, so that j is greater than the number of the last listed node of mesh face i, then the cell data element contains zero (0). The edges of each mesh face i are implicitly defined by pairing node j to node j + 1.

If the field value topology_present is set to True, then the <DRM Finite Element Mesh> will contain a second data element in the cell data.  The second data element defines surface topology by indicating, for each edge (j, j + 1) of mesh face i, the index of mesh face k (if any) that is adjacent to mesh face i along the edge. A value of 0 indicates an "outside" or "universal" adjacency. A value of i for mesh face i indicates that the edge is artificially connecting an inside perimeter ring to another perimeter ring.

For a given mesh face element index i and mesh face node index j, the (i, j)-th cell gives the vertex number that comprises the j-th node of the i-th mesh face. The mesh face vertices are listed (j index) in clockwise order around the outer perimeter of the mesh face, starting and ending with a first vertex. If inner perimeter rings are present, the vertex list along the second axis continues with inner perimeter vertices in counter-clockwise order starting and ending with a first vertex on each inner ring.

Example(s)

· Consider six <DRM Vertex> instances, used to define a <DRM Mesh Face Table>, where the mesh would be diagrammed as follows.

In this example, there are six <DRM Vertex> instances forming the nodes of the mesh, which has three mesh faces (A, B, C).

The corresponding <DRM Mesh Face Table>, without surface topology, would be organized as follows, where each individual cell contains a vertex number.

	Vertex Index
Face Index	1	2	3	4	5
1 (Mesh Face A)	1	2	4	1	0
2 (Mesh Face B)	2	3	6	5	2
3 (Mesh Face C)	4	2	5	4	0

· Consider the <DRM Mesh Face Table> from the previous example, with the addition of surface topology (i.e., topology_present set to TRUE). In this instance, each individual cell contains a {vertex number, adjacent mesh face number} pair.

	Vertex Index
Face Index	1	2	3	4	5
1 (Mesh Face A)	1, 0	2, 3	4, 0	1, 0	0, 0
2 (Mesh Face B)	2, 0	3, 0	6, 0	5, 3	2, 0
3 (Mesh Face C)	4, 1	2, 2	5, 0	4, 0	0, 0

Inherited field elements

field_name	range	Field_Data_Type
none

Field elements

field_name	range	Field_Data_Type
total_mesh_faces		Integer_Positive
max_nodes_and_rings^1		Integer_Positive
topology_present		Boolean

Associated to (one-way) (inherited)

· none

Associated to (one-way)

· none

Associated by (one-way) (inherited)

· none

Associated by (one-way)

· none

Associated with (two-way) (inherited)

· none

Associated with (two-way)

· none

Composed of (two-way) (inherited)

· zero or more {ordered} <DRM Image Mapping Function>s 

· zero or one <DRM Time Constraints Data>

Composed of (two-way)

· none

Composed of (two-way metadata) (inherited)

· zero or one <DRM Access>

· zero or more <DRM Browse Media>s

· zero or one <DRM Citation>

· zero or more <DRM Cross Reference>s

· zero or one <DRM Data Quality>

· zero or one <DRM Description>

· zero or one <DRM Keywords>

· zero or one <DRM Point Of Contact>

Composed of (two-way metadata)

· none

Component of (two-way) (inherited)

· zero or one <DRM Data Table Library>

· zero or more <DRM Property Grid>s

Component of (two-way)

· one <DRM Finite Element Mesh>

Constraints

· Index codes within tables

Notes

¹ max_nodes_and_rings is the sum of the maximum number of nodes in any one face element in the table and the maximum number of perimeter rings in any one face element.  If all the face elements have simply connected perimeters, the maximum number of perimeter rings is one.

Class diagram

<DRM Mesh Face Table>