Entity Sets (Group)

Overview

The Group class maintains lists of active entities such as elements and nodes and child entities such as element faces and edges. The terms “element” and “node” will be used as generic terms in place of “cell” and “vertex” which are typically used in reference to block structured grids.

Users of a Group object may set or query for active entities. The Group class also supports Boolean operations so that entity subsets may be combined, intersected, copied, etc. Normally the active entities in a Group object are set by a function in another class such as getFaceGroup() in the Mesh class. The functions associated with a Group object are the following.

Definition
- define() - Define parent and child entities
- inquire() - Inquire parent and child entities
Set, manipulate and query active entities
- isNodeActive() - Query for active node
- isElementActive() - Query for active element
- isElementEntityActive() - Query for active element edge or face
- all() - Set all entities active
- clear() - Set all entities inactive
- complement() - Reverse entity activities
- count() - Count active entities
- createFromIdTranslator() - Convert IdTranslator object
- initializeIndexIteration() - Initialize NextIndex function
- nextIndex() - Get next active entity index
- setIndex() - Set entity as active or inactive
- getIndex() - Get entity activity by index
- setIndices() - Set entities as active or inactive
- entityFlagSetCount() - Get number of entity flags by index
- setEntityFlag() - Set entity flag by index and number
- getEntityFlag() - Get entity flag by index and number
- setName() - Set name string
- getName() - Get name string
- setType() - Set type
- getType() - Get type
- setSpecificType() - Set specific type
- getSpecificType() - Get specific type
General functions
- getErrorCode() - Get error code
- copy() - Copy a Group

Define parent and child entity types and parent entity size with define() . Currently allowable entity types are parent element and node, and child face and edge. The child entity type is optional. The following four combinations are permitted (1) element, (2) element face, (3) element edge, and (4) node. If the exact number of parent entities to be entered into a Group object is unknown, then make an initial estimate, (0 is allowed), and call define() with that estimate. The Group object will adjust memory dynamically if required.

The actual data structures used to hold active entity flags are private to the Group object. The user accesses active entities in a Group using a suite of functions. These functions fall into three basic categories, (1) query for the activity flags of a particular entity by index, (2) query for the activity flag of a particular entity by index and edge or face number, (3) query for the index of the “next” active entity.

The activity flags which are returned for basic element and node entities, using getIndex() for example, are returned as the low order bit in an integer data type. For non polygonal or polyhedral finite element shapes the flags for element faces are returned encoded as the low order 6 bits in an integer. Each bit set indicates that the associated element face (numbered 1 to 6 in a hexahedron for example) is active. The flags for element edges are returned encoded as the low order 12 bits in an integer. Each bit set indicates that the associated element edge (numbered 1 to 12 in a hexahedron for example) is active. For polygonal and polyhedral shapes (POLYGON and POLYHEDRON) the integer activity index only encodes the activity flags for the first 32 edges or faces. The function getEntityFlag() has been designed to query any activity flag individually by index and edge or face number.

The functions isNodeActive(), isElementActive() , and isElementEntityActive() are designed to test for activity flag(s) and return the flag as the return value of the function.

Boolean and other Operations on Group objects may be performed using all(), clear(), copy() and complement(). The createFromIdTranslator() function may be used to convert an ordered list of identifiers in an IdTranslator object into a set of active entity flags in a Group object.

As a convenience, a name string may be associated with the Group object using setName(). The functions setType(), getType() and setSpecificType() , getSpecificType() may be used to set useful integer data which describe the general and specific types of the group. These integers are usually set to the values associated with the element associations ELEMENT_TYPE and ELEMENT_SPECIFIC_TYPE respectively.

Class Members Descriptions

The currently available Group enumerations and functions are described in detail in this section.

class Group

Object for Entity Sets management.

Public Types

enum class Operation

Group operation type for combining or modifying groups.

Values:

enumerator SET: Set/replace group contents.

enumerator INSERT: Insert/add to group.

enumerator REMOVE: Remove from group.

enumerator MASK: Apply mask operation.

Public Functions

HOOPS_CAE_EXTERN ErrorCode getErrorCode ()

Return the current ErrorCode of the Group object.

Returns:	`ErrorCode` - The current error code, or `NONE` if no error.

HOOPS_CAE_EXTERN Status define (int entityCount, EntityType entityType, EntityType entitySubtype)

Specify the number of parent entities and type of parent and child entities. A child entity type may be specified if element faces or element edges are to be managed by the group. If purely elements or nodes are to be managed by the group, then entitySubtype should be set to NONE . This function call initializes all entities to be inactive.

Parameters:	nodeIndex – Index of node entity
Returns:	The activity flag for the node

Parameters:	elementIndex – Index of element entity
Returns:	The activity flag for the element

Parameters:	elementEntityIndex – Index of element entity elementEntityNumber – Element edge or face number
Returns:	The activity flag for the element edge or face

Entity Sets (Group)

Overview

Class Members Descriptions

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