8.9.3.66 IfcSpiral

ABSTRACT This definition may not be instantiated

8.9.3.66.1 Semantic 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.

8.9.3.66.2 Entity inheritance

8.9.3.66.3 Attributes

#	Attribute	Type	Description
IfcRepresentationItem (2)
	LayerAssignment	SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems	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.
	StyledByItem	SET [0:1] OF IfcStyledItem FOR Item	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.
IfcCurve (1)
*	Dim	IfcDimensionCount	This attribute is formally derived. `IfcCurveDim(SELF)` The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.
Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes
IfcSpiral (1)
1	Position	IfcAxis2Placement	No description available.

Table 8.9.3.66.A

8.9.3.66.4 Formal representation

ENTITY IfcSpiral
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcClothoid
	,IfcCosineSpiral
	,IfcSecondOrderPolynomialSpiral
	,IfcSeventhOrderPolynomialSpiral
	,IfcSineSpiral
	,IfcThirdOrderPolynomialSpiral))
 SUBTYPE OF (IfcCurve);
	Position : IfcAxis2Placement;
END_ENTITY;