IFC (IFC4X3) development IfcOffsetCurveByDistances Semantic definition

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 illustrates eight instances of IfcOffsetCurveByDistances (in green) defined relative to an IfcGradientCurve (in blue).

spatial structure
Figure — Offset curve by distances
spatial structure
Figure — Usage of OffsetValues Entity inheritance 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.

IfcCurve (1)
* Dim IfcDimensionCount

This attribute is formally derived.


The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.

IfcOffsetCurve (1)
1 BasisCurve IfcCurve

The curve that is being offset.

Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcOffsetCurveByDistances (2)
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.

Table Formal representation

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

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