IFC 4.3.x development

8.9.3.43 IfcOffsetCurveByDistances

Change log

IFC4X1

added

IFC4X3_RC3

modificationsattributes OffsetValues definitionChanged from list[1:?] of IfcDistanceExpression to list[1:?] of IfcPointByDistanceExpression

8.9.3.43.1 Semantic definitions at the entity

An IfcOffsetCurveByDistances is a curve defined by a list of offsets along its BasisCurve. If only one offset is provided, it indicates a constant offset along the extents of the basis curve.

Figure 1 illustrates eight instances of IfcOffsetCurveByDistances (in green) defined relative to an IfcAlignmentCurve (in blue).

"spatial structure"

8.9.3.43.1 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
IfcCurve
Dim INVALID The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.
IfcOffsetCurve
1 BasisCurve IfcCurve The curve that is being offset.
IfcOffsetCurveByDistances
2 OffsetValues LIST [1:?] OF IfcPointByDistanceExpression List of sequential points described relative to the basis curve. If the offsets do not span the full extent of the basis curve (e.g. if the list contains only one item), then the lateral and vertical offsets implicitly continue with the same value towards the head and tail of the basis curve.
3 Tag OPTIONAL IfcLabel Optional identifier of the curve, which may be used to correlate points from a variable cross-section.

8.9.3.43.2 Entity inheritance

dot_inheritance IfcOffsetCurveByDistances IfcOffsetCurveByDistances IfcOffsetCurve IfcOffsetCurve IfcOffsetCurveByDistances->IfcOffsetCurve IfcOffsetCurve2D IfcOffsetCurve2D IfcOffsetCurve2D->IfcOffsetCurve IfcCurve IfcCurve IfcOffsetCurve->IfcCurve IfcOffsetCurve3D IfcOffsetCurve3D IfcOffsetCurve3D->IfcOffsetCurve IfcCurve_children 7 more... IfcCurve_children->IfcCurve IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcCurve->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.9.3.43.3 Formal representations

ENTITY IfcOffsetCurveByDistances
 SUBTYPE OF (IfcOffsetCurve);
	OffsetValues : LIST [1:?] OF IfcPointByDistanceExpression;
	Tag : OPTIONAL IfcLabel;
END_ENTITY;