8.18.3.20 IfcTopologyRepresentation
8.18.3.20.1 Semantic definition
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:
| Type | Description |
|---|---|
| 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'.
8.18.3.20.2 Entity inheritance
8.18.3.20.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRepresentation (7) | |||
| 1 | ContextOfItems | IfcRepresentationContext |
Definition of the representation context for which the different subtypes of representation are valid. |
| 2 | RepresentationIdentifier | OPTIONAL 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. |
| LayerAssignments | SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItems |
Assignment 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. |
|
| 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. |
|
| 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. |
|
| Click to show 7 hidden inherited attributes Click to hide 7 inherited attributes | |||
| IfcShapeModel (1) | |||
| OfShapeAspect | SET [0:1] OF IfcShapeAspect FOR ShapeRepresentations |
Reference to the shape aspect, for which it is the shape representation. |
|
8.18.3.20.4 Formal propositions
| Name | Description |
|---|---|
| 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. |
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8.18.3.20.5 Formal representation
ENTITY IfcTopologyRepresentation
SUBTYPE OF (IfcShapeModel);
WHERE
WR21 : SIZEOF(QUERY(temp <* SELF\IfcRepresentation.Items |
NOT('IFC4X4_DEV_20260525.IFCTOPOLOGICALREPRESENTATIONITEM' IN TYPEOF(temp))
)) = 0;
WR22 : EXISTS(SELF\IfcRepresentation.RepresentationType);
WR23 : IfcTopologyRepresentationTypes(SELF\IfcRepresentation.RepresentationType, SELF\IfcRepresentation.Items);
END_ENTITY;
