#### IfcCircle

Natural language names

##### 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

`

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