IFC 4.3.x development

8.9.3.25 IfcCurve

8.9.3.25.1 Semantic definitions at the entity

An IfcCurve is a curve in two-dimensional or three-dimensional space. It includes definitions for bounded and unbounded curves.

NOTE  Definition according to ISO 10303-42:
A curve can be envisioned as the path of a point moving in its coordinate space.

NOTE Entity adapted from curve defined in ISO 10303-42

HISTORY  New entity in IFC1.0

Informal Propositions:

  1. A curve shall be arcwise connected
  2. A curve shall have an arc length greater than zero.

8.9.3.25.1 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.

8.9.3.25.2 Entity inheritance

dot_inheritance IfcCurve_children 7 more... IfcCurve IfcCurve 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

8.9.3.25.3 Formal representations

ENTITY IfcCurve
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcBoundedCurve
	,IfcConic
	,IfcLine
	,IfcOffsetCurve
	,IfcPcurve
	,IfcPolynomialCurve
	,IfcSpiral
	,IfcSurfaceCurve))
 SUBTYPE OF (IfcGeometricRepresentationItem);
 DERIVE
	 Dim : IfcDimensionCount := IfcCurveDim(SELF);
END_ENTITY;