IFC 4.3.0.1 (IFC4X3) development

8.8.3.21 IfcGeometricSet

8.8.3.21.1 Semantic definition

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).

8.8.3.21.2 Entity inheritance

8.8.3.21.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

Assignment 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.

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.

Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcGeometricSet (2)
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 IfcDimensionCount

This attribute is formally derived.

Elements[1].Dim

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.

Table 8.8.3.21.A

8.8.3.21.4 Formal propositions

Name Description
ConsistentDim

All elements within a geometric set shall have the same dimensionality.

SIZEOF(QUERY(Temp <* Elements |
  Temp.Dim <> Elements[1].Dim))
= 0
Table 8.8.3.21.B

8.8.3.21.5 Formal representation

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;

8.8.3.21.6 References

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8.8.3.21.7 Changelog

  • where rule, ConsistentDim
  • where rule, WR21