IfcCircle

Semantic definitions at the entity

Entity definition

An IfcCircle is a curve consisting of a set of points having equal distance from the center.

NOTE A circular arc segment is defined by using the IfcTrimmedCurve with BasisCurve being an IfcCircle.

Figure 516 illustrates the definition of IfcCircle within a three-dimensional position coordinate system placed within the object coordinate system of an element.

Figure 516 — Circle layout

NOTE Definition according to ISO/CD 10303-42:1992
A circle is defined by a radius and the location and orientation of the circle. Interpretation of data should be as follows:
C = SELF\IfcConic.Position.Location  
x = SELF\IfcConic.Position.P[1]  
y = SELF\IfcConic.Position.P[2]  
z = SELF\IfcConic.Position.P[3]  
R = Radius
and the circle is parameterized as

The parameterization range is 0 ≤ u ≤ 2π (0 ≤ u ≤ 360 degree).
In the placement coordinate system defined above, the circle is the equation C = 0, where

The positive sense of the circle at any point is in the tangent direction, T, to the curve at the point, where

NOTE Entity adapted from circle defined in ISO 10303-42

HISTORY New entity in IFC1.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
2	Radius	IfcPositiveLengthMeasure		The radius of the circle, which shall be greater than zero.	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
IfcConic
1	Position	IfcAxis2Placement		The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes."	X
IfcCircle
2	Radius	IfcPositiveLengthMeasure		The radius of the circle, which shall be greater than zero.	X

Formal representations

XML Specification

 <xs:element name="IfcCircle" type="ifc:IfcCircle" substitutionGroup="ifc:IfcConic" nillable="true"/>

 <xs:complexType name="IfcCircle">

  <xs:complexContent>

   <xs:extension base="ifc:IfcConic">

    <xs:attribute name="Radius" type="ifc:IfcPositiveLengthMeasure" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcCircle

 SUBTYPE OF (IfcConic);

  Radius : IfcPositiveLengthMeasure;

END_ENTITY;

 EXPRESS-G diagram

	Kreis
	Circle
	Cercle