IFC 4.3.x development

8.9.3.47 IfcPcurve

Change log

IFC4

added

8.9.3.47.1 Semantic definitions at the entity

The IfcPcurve is a curve defined within the parameter space of its reference surface.

NOTE  Definition according to ISO/CD 10303-42:1992
A pcurve is a curve which lies on the basis of a surface and is defined in the parameter space of that surface. The basis curve is a curve defined in the two-dimensional parametric space of a reference basis surface. Although it is defined by a curve in two dimensional space, the variables involved are u and v, which occur in the parametric representation of the referenced surface, rather than the x, y, Cartesian coordinates. The basis curve is only defined within the parametric range of the surface.

NOTE  Entity adapted from pcurve in ISO 10303-42.

HISTORY  New entity in IFC4.

8.9.3.47.1 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.
IfcPcurve
1 BasisSurface IfcSurface
2 ReferenceCurve IfcCurve

8.9.3.47.2 Entity inheritance

dot_inheritance IfcPcurve IfcPcurve IfcCurve IfcCurve IfcPcurve->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

8.9.3.47.3 Formal representations

ENTITY IfcPcurve
 SUBTYPE OF (IfcCurve);
	BasisSurface : IfcSurface;
	ReferenceCurve : IfcCurve;
 WHERE
	DimIs2D : ReferenceCurve.Dim = 2;
END_ENTITY;