IfcCircle

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: An IfcCircle 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 £2p (or 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 A circular arc is defined by using the trimmed curve (IfcTrimmedCurve) entity in conjunction with the circle (IfcCircle) entity as the BasisCurve.

NOTE Corresponding STEP entity: circle, please refer to ISO/IS 10303-42:1994, p. 38 for the final definition of the formal standard.

HISTORY New class in IFC Release 1.0

Illustration:

Definition of the IfcCircle within the (in this case three-dimensional) position coordinate system.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
2	Radius	IfcPositiveLengthMeasure	[1:1]	The radius of the circle, which shall be greater than zero.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcCurve
	Dim :=IfcCurveDim(SELF)	IfcDimensionCount	[1:1]	The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.	X
IfcConic
1	Position	IfcAxis2Placement	[1:1]	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	[1:1]	The radius of the circle, which shall be greater than zero.	X

Formal representations

XSD 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