IFC 4.3.x development

8.9.3.64 IfcSegmentedReferenceCurve

Change log

IFC4X3_RC3

added

8.9.3.64.1 Semantic definitions at the entity

A segmented reference curve is constructed from a referenced base curve (BaseCurve) that should in most cases (there can be exceptions) be used for positioning of a list of IfcCurveSegment occurrences. The type of the base curve that IfcCurveSegment references provides the information of the interpolation method between the start point of the segment and its end point defined by the segment length of the IfcCurveSegment.ParentCurve.

The parametrization of IfcSegmentReferenceCurve is based on the parametrization of BaseCurve and is not altered by the Segments.

Figure 1 shows a cross section of a IfcSegmentedReferenceCurve usage for an alignmnent representation featuring cant

"segmented reference curve usage"

8.9.3.64.1 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.
IfcBoundedCurve
IfcCompositeCurve
1 Segments LIST [1:?] OF IfcSegment The component bounded curves, their transitions and senses. The transition attribute for the last segment defines the transition between the end of the last segment and the start of the first; this transition attribute may take the value discontinuous, which indicates an open curve.

> NOTE : For IfcGradientCurve and IfcSegmentedReferenceCurve the segments define the interpolation between segment start and and segment end.
2 SelfIntersect IfcLogical Indication of whether the curve intersects itself or not; this is for information only.
NSegments INVALID The number of component curves.
ClosedCurve INVALID Indication whether the curve is closed or not; this is derived from the transition code of the last segment.
IfcSegmentedReferenceCurve
3 BaseCurve IfcBoundedCurve
4 EndPoint OPTIONAL IfcPlacement

8.9.3.64.2 Entity inheritance

dot_inheritance IfcSegmentedReferenceCurve IfcSegmentedReferenceCurve IfcCompositeCurve IfcCompositeCurve IfcSegmentedReferenceCurve->IfcCompositeCurve IfcCompositeCurveOnSurface IfcCompositeCurveOnSurface IfcCompositeCurveOnSurface->IfcCompositeCurve IfcBoundedCurve IfcBoundedCurve IfcCompositeCurve->IfcBoundedCurve IfcGradientCurve IfcGradientCurve IfcGradientCurve->IfcCompositeCurve IfcBoundedCurve_children 5 more... IfcBoundedCurve_children->IfcBoundedCurve IfcCurve IfcCurve IfcBoundedCurve->IfcCurve 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

8.9.3.64.3 Formal representations

ENTITY IfcSegmentedReferenceCurve
 SUBTYPE OF (IfcCompositeCurve);
	BaseCurve : IfcBoundedCurve;
	EndPoint : OPTIONAL IfcPlacement;
END_ENTITY;