IFC 4.3.x development

8.18.3.17 IfcTopologyRepresentation

Change log

IFC4

modificationswhere_rules WR21 definitionChanged from sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc2x3.ifctopologicalrepresentationitem' in typeof(temp)))) = 0 to sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4.ifctopologicalrepresentationitem' in typeof(temp)))) = 0

IFC4X1

modificationswhere_rules WR21 definitionChanged from sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4.ifctopologicalrepresentationitem' in typeof(temp)))) = 0 to sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4x1.ifctopologicalrepresentationitem' in typeof(temp)))) = 0

IFC4X2

modificationswhere_rules WR21 definitionChanged from sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4x1.ifctopologicalrepresentationitem' in typeof(temp)))) = 0 to sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4x2.ifctopologicalrepresentationitem' in typeof(temp)))) = 0

IFC4X3_RC3

modificationswhere_rules WR21 definitionChanged from sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4x2.ifctopologicalrepresentationitem' in typeof(temp)))) = 0 to sizeof(query(temp <* self\IfcRepresentation.Items | not('ifc4x3_rc3.ifctopologicalrepresentationitem' in typeof(temp)))) = 0

8.18.3.17.1 Semantic definitions at the entity

IfcTopologyRepresentation represents the concept of a particular topological representation of a product or a product component within a representation context. This representation context does not need to be (but may be) a geometric representation context. Several representation types for shape representation are included as predefined types:

Vertex topological vertex representation (with or without assigned geometry)
Edge topological edge representation (with or without assigned geometry)
Path topological path representation (with or without assigned geometry)
Face topological face representation (with or without assigned geometry)
Shell topological shell representation (with or without assigned geometry)
Undefined no constraints imposed

The representation type is given as a string value at the inherited attribute 'RepresentationType'.

HISTORY  New entity in IFC2x2.

Formal Propositions

WR21

Only topological representation items should be used.

WR22

A representation type should be given to the topology representation.

WR23

Checks the proper use of Items according to the RepresentationType.

# Attribute Type Description
IfcRepresentation
1 ContextOfItems IfcRepresentationContext Definition of the representation context for which the different subtypes of representation are valid.
2 RepresentationIdentifierOPTIONAL IfcLabel The optional identifier of the representation as used within a project.
3 RepresentationType OPTIONAL IfcLabel The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation.

The supported values for context type are to be specified by implementers agreements.
4 Items SET [1:?] OF IfcRepresentationItem Set of geometric representation items that are defined for this representation.
RepresentationMap SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added
LayerAssignments SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the whole representation to a single or multiple layer(s). The LayerAssigments can be overridden by LayerAssigments of the IfcRepresentationItem's within the list of Items.

> NOTE  Implementation agreements can restrict the maximum number of layer assignments to 1.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added
OfProductRepresentation SET [0:?] OF IfcProductRepresentation FOR Representations Reference to the product representations to which this individual representation applies. In most cases it is the reference to one or many product shapes, to which this shape representation is applicable.

> IFC4 CHANGE Inverse relationship cardinality relaxed to be 0:N.
IfcShapeModel
OfShapeAspect SET [0:1] OF IfcShapeAspect FOR ShapeRepresentations Reference to the shape aspect, for which it is the shape representation.

8.18.3.17.1 Entity inheritance

dot_inheritance IfcTopologyRepresentation IfcTopologyRepresentation IfcShapeModel IfcShapeModel IfcTopologyRepresentation->IfcShapeModel IfcShapeRepresentation IfcShapeRepresentation IfcShapeRepresentation->IfcShapeModel IfcRepresentation IfcRepresentation IfcShapeModel->IfcRepresentation IfcStyleModel IfcStyleModel IfcStyleModel->IfcRepresentation

8.18.3.17.2 Formal representations

ENTITY IfcTopologyRepresentation
 SUBTYPE OF (IfcShapeModel);
 WHERE
	WR21 : SIZEOF(QUERY(temp <* SELF\IfcRepresentation.Items | 
  NOT('IFC4X3_DEV.IFCTOPOLOGICALREPRESENTATIONITEM' IN TYPEOF(temp))
)) = 0

;
	WR22 : EXISTS(SELF\IfcRepresentation.RepresentationType);
	WR23 : IfcTopologyRepresentationTypes(SELF\IfcRepresentation.RepresentationType, SELF\IfcRepresentation.Items);
END_ENTITY;