IFC 4.3.x development

8.8.3.21 IfcGeometricSet

Change log

IFC4

additionswhere_rulesConsistentDim
deletionswhere_rulesWR21

8.8.3.21.1 Semantic definitions at the entity

The IfcGeometricSet is used for the exchange of shape representation consisting of (2D or 3D) points, curves, and surfaces, which do not have a topological structure (such as connected face sets or shells), are not tessellated and are not solid models (such as swept solids, CSG or Brep).

NOTE  Definition from ISO/CD 10303-42:
This entity is intended for the transfer of models when a topological structure is not available.

NOTE  Entity adapted from geometric_set defined in ISO 10303-42.

HISTORY  New entity in IFC2x.

8.8.3.21.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignmentSET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.



> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
IfcGeometricRepresentationItem
IfcGeometricSet
1 Elements SET [1:?] OF IfcGeometricSetSelect The geometric elements which make up the geometric set, these may be points, curves or surfaces; but are required to be of the same coordinate space dimensionality.
Dim INVALID The space dimensionality of this class, it is identical to the first element in the set. A where rule ensures that all elements have the same dimensionality.

8.8.3.21.2 Entity inheritance

dot_inheritance IfcGeometricCurveSet IfcGeometricCurveSet IfcGeometricSet IfcGeometricSet IfcGeometricCurveSet->IfcGeometricSet IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcGeometricSet->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.8.3.21.3 Formal representations

ENTITY IfcGeometricSet
 SUPERTYPE OF (ONEOF
	(IfcGeometricCurveSet))
 SUBTYPE OF (IfcGeometricRepresentationItem);
	Elements : SET [1:?] OF IfcGeometricSetSelect;
 DERIVE
	 Dim : IfcDimensionCount := Elements[1].Dim;
 WHERE
	ConsistentDim : SIZEOF(QUERY(Temp <* Elements |
  Temp.Dim <> Elements[1].Dim))
= 0;
END_ENTITY;