IfcPcurve

Natural language names
Kurve im Parameterraum einer Fläche
Pcurve
Courbe basée sur une surface
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4 4.0.0.0
    IfcPcurveADDED
Semantic definitions at the entity
Entity definition

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.

Attribute definitions
#AttributeTypeCardinalityDescription G
1BasisSurfaceIfcSurface X
2ReferenceCurveIfcCurve X
Formal Propositions
RuleDescription
DimIs2DThe dimensionality of the parameter space curve shall be 2.
Inherited definitions from supertypes
Entity inheritance IfcCurve IfcGeometricRepresentationItem IfcRepresentationItem
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRepresentationItem
LayerAssignmentIfcPresentationLayerAssignment
@AssignedItems
S[0:1]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.
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.
X
StyledByItemIfcStyledItem
@Item
S[0:1]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.
X
IfcGeometricRepresentationItem
IfcCurve
Dim
:=IfcCurveDim(SELF)
IfcDimensionCountThe space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. X
IfcPcurve
1BasisSurfaceIfcSurface X
2ReferenceCurveIfcCurve X
Formal representations
XML Specification
 <xs:element name="IfcPcurve" type="ifc:IfcPcurve" substitutionGroup="ifc:IfcCurve" nillable="true"/>
 <xs:complexType name="IfcPcurve">
  <xs:complexContent>
   <xs:extension base="ifc:IfcCurve">
    <xs:sequence>
     <xs:element name="BasisSurface" type="ifc:IfcSurface" nillable="true"/>
     <xs:element name="ReferenceCurve" type="ifc:IfcCurve" nillable="true"/>
    </xs:sequence>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcPcurve
 SUBTYPE OF (IfcCurve);
  BasisSurface : IfcSurface;
  ReferenceCurve : IfcCurve;
 WHERE
  DimIs2D : ReferenceCurve.Dim = 2;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcSurfaceCurve IfcCurveOnSurface

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