IfcOffsetCurveByDistances

Item	SPF	XML	Change	Description
IFC4x1 Final 4.1.0.0
IfcOffsetCurveByDistances			ADDED
IFC4x3_RC1 to IFC4x3_RC2
IfcOffsetCurveByDistances
OffsetValues	X	X	MODIFIED	Type changed from IfcDistanceExpression to IfcPointByDistanceExpression.

Semantic definitions at the entity

Entity definition

An IfcOffsetCurveByDistances is a curve defined by a list of offsets along its BasisCurve. If only one offset is provided, it indicates a constant offset along the extents of the basis curve.

Figure 522 illustrates eight instances of IfcOffsetCurveByDistances (in green) defined relative to an IfcAlignmentCurve (in blue).

Figure 522 — Offset curve by distances

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
2	OffsetValues	IfcPointByDistanceExpression	L[1:?]	List of sequential points described relative to the basis curve. If the offsets do not span the full extent of the basis curve (e.g. if the list contains only one item), then the lateral and vertical offsets implicitly continue with the same value towards the head and tail of the basis curve.	X
3	Tag	IfcLabel	?	Optional identifier of the curve, which may be used to correlate points from a variable cross-section.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
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
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
IfcOffsetCurve
1	BasisCurve	IfcCurve		The curve that is being offset.	X
IfcOffsetCurveByDistances
2	OffsetValues	IfcPointByDistanceExpression	L[1:?]	List of sequential points described relative to the basis curve. If the offsets do not span the full extent of the basis curve (e.g. if the list contains only one item), then the lateral and vertical offsets implicitly continue with the same value towards the head and tail of the basis curve.	X
3	Tag	IfcLabel	?	Optional identifier of the curve, which may be used to correlate points from a variable cross-section.	X

Formal representations

XML Specification

 <xs:element name="IfcOffsetCurveByDistances" type="ifc:IfcOffsetCurveByDistances" substitutionGroup="ifc:IfcOffsetCurve" nillable="true"/>

 <xs:complexType name="IfcOffsetCurveByDistances">

  <xs:complexContent>

   <xs:extension base="ifc:IfcOffsetCurve">

    <xs:sequence>

     <xs:element name="OffsetValues">

      <xs:complexType>

       <xs:sequence>

        <xs:element ref="ifc:IfcPointByDistanceExpression" maxOccurs="unbounded"/>

       </xs:sequence>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcPointByDistanceExpression"/>

       <xs:attribute ref="ifc:cType" fixed="list"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

    <xs:attribute name="Tag" type="ifc:IfcLabel" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcOffsetCurveByDistances

 SUBTYPE OF (IfcOffsetCurve);

  OffsetValues : LIST [1:?] OF IfcPointByDistanceExpression;

  Tag : OPTIONAL IfcLabel;

END_ENTITY;

 EXPRESS-G diagram