IFC 4.3.x development

8.9.3.9 IfcBoundaryCurve

Change log

IFC4

added

8.9.3.9.1 Semantic definitions at the entity

An IfcBoundaryCurve defines a curve acting as the boundary of a surface.

NOTE  Definition according to ISO/CD 10303-42:1992
A boundary curve is a type of bounded curve suitable for the definition of a surface boundary.

NOTE  Entity adapted from boundary_curve defined in ISO10303-42.

HISTORY  New entity in IFC4.

Formal Propositions

IsClosed

The derived ClosedCurve attribute of IfcCompositeCurve supertype shall be TRUE.

# 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.
IfcCompositeCurveOnSurface
BasisSurface INVALID The surface on which the composite curve is defined.

8.9.3.9.1 Entity inheritance

dot_inheritance IfcOuterBoundaryCurve IfcOuterBoundaryCurve IfcBoundaryCurve IfcBoundaryCurve IfcOuterBoundaryCurve->IfcBoundaryCurve IfcCompositeCurveOnSurface IfcCompositeCurveOnSurface IfcBoundaryCurve->IfcCompositeCurveOnSurface IfcCompositeCurve IfcCompositeCurve IfcCompositeCurveOnSurface->IfcCompositeCurve IfcGradientCurve IfcGradientCurve IfcGradientCurve->IfcCompositeCurve IfcBoundedCurve IfcBoundedCurve IfcCompositeCurve->IfcBoundedCurve IfcSegmentedReferenceCurve IfcSegmentedReferenceCurve IfcSegmentedReferenceCurve->IfcCompositeCurve IfcBoundedCurve_children 4 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

8.9.3.9.2 Formal representations

ENTITY IfcBoundaryCurve
 SUPERTYPE OF (ONEOF
	(IfcOuterBoundaryCurve))
 SUBTYPE OF (IfcCompositeCurveOnSurface);
 WHERE
	IsClosed : SELF\IfcCompositeCurve.ClosedCurve;
END_ENTITY;