IfcSpiral

Item	SPF	XML	Change	Description
IFC4x3_RC2 to IFC4x3_RC3
IfcSpiral			ADDED

Semantic definitions at the entity

Entity definition

Spirals are curves that revolve around a point while increasing its length. In general, these curves are parameterized in the following way: x = r(φ) cosφ y = r(φ) sinφ

In the case of the clothoid and higher order transition spirals, the parametrization is: x = ∫cos &Theta dl y = ∫sin &Theta dl

where &Theta is the deflection or bearing angle and dl the differential of the spiral length.

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
1	Position	IfcAxis2Placement			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
IfcSpiral
1	Position	IfcAxis2Placement			X

Formal representations

XML Specification

 <xs:element name="IfcSpiral" type="ifc:IfcSpiral" abstract="true" substitutionGroup="ifc:IfcCurve" nillable="true"/>

 <xs:complexType name="IfcSpiral" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcCurve">

    <xs:sequence>

     <xs:element name="Position">

      <xs:complexType>

       <xs:group ref="ifc:IfcAxis2Placement"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcSpiral

 ABSTRACT SUPERTYPE OF(ONEOF(IfcClothoid, IfcCosineSpiral, IfcSecondOrderPolynomialSpiral, IfcSeventhOrderPolynomialSpiral, IfcSineSpiral, IfcThirdOrderPolynomialSpiral))

 SUBTYPE OF (IfcCurve);

  Position : IfcAxis2Placement;

END_ENTITY;

 EXPRESS-G diagram