IfcCurve

BACnet MVD

#### IfcCurve

Natural language names

| Kurve
| Curve
| Courbe

##### Semantic definitions at the entity

Entity definition

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.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
| Dim :=IfcCurveDim(SELF) | IfcDimensionCount |  | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRepresentationItem

LayerAssignment

IfcPresentationLayerAssignment
@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

StyledByItem

IfcStyledItem
@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

X

IfcGeometricRepresentationItem
IfcCurve
| Dim :=IfcCurveDim(SELF) | IfcDimensionCount |  | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcCurve" type="ifc:IfcCurve" abstract="true" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcCurve" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem"/>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcCurve
ABSTRACT SUPERTYPE OF(ONEOF(IfcBoundedCurve, IfcConic, IfcLine, IfcOffsetCurve2D, IfcOffsetCurve3D, IfcPcurve, IfcSurfaceCurve))
SUBTYPE OF (IfcGeometricRepresentationItem);
DERIVE
Dim : IfcDimensionCount := IfcCurveDim(SELF);
END_ENTITY;

EXPRESS-G diagram

`

References: IfcGridAxis IfcFixedReferenceSweptAreaSolid IfcSurfaceCurveSweptAreaSolid IfcSweptDiskSolid IfcGeometricSetSelect IfcCompositeCurveSegment IfcCurveBoundedPlane IfcOffsetCurve2D IfcOffsetCurve3D IfcPcurve IfcPointOnCurve IfcSurfaceCurve IfcTrimmedCurve IfcAnnotationFillArea IfcArbitraryClosedProfileDef IfcArbitraryProfileDefWithVoids IfcEdgeCurve

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