IfcOffsetCurveByDistances

Natural language names
Offset Curve By Distances
Change log
ItemSPFXMLChangeDescription
IFC4x1 Release Candidate 3
    IfcOffsetCurveByDistancesADDED
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 377 illustrates eight instances of IfcOffsetCurveByDistances (in green) defined relative to an IfcAlignmentCurve (in blue).

spatial structure

Figure 377 — Offset curve by distances

Attribute definitions
#AttributeTypeCardinalityDescription G
2OffsetValuesIfcDistanceExpressionL[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
3TagIfcLabel? Optional identifier of the curve, which may be used to correlate points from a variable cross-section.X
Inherited definitions from supertypes
Entity inheritance IfcOffsetCurve 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
IfcOffsetCurve
1BasisCurveIfcCurve The curve that is being offset.X
IfcOffsetCurveByDistances
2OffsetValuesIfcDistanceExpressionL[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
3TagIfcLabel? Optional identifier of the curve, which may be used to correlate points from a variable cross-section.X
Examples
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:IfcDistanceExpression" maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcDistanceExpression"/>
       <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 IfcDistanceExpression;
  Tag : OPTIONAL IfcLabel;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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