IfcCircle

BACnet MVD

#### IfcCircle

Natural language names

| Kreis
| Circle
| Cercle

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

Figure 315 — 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 | B
--- | --- | --- | --- | --- | ---
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 | B
--- | --- | --- | --- | --- | ---
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

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 | 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

`

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