8.9.3.18 IfcCircle
8.9.3.18.1 Semantic definition
An IfcCircle is a curve consisting of a set of points having equal distance from the center.
Figure 8.9.3.18.A illustrates the definition of IfcCircle within a three-dimensional position coordinate system placed within the object coordinate system of an element.
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
The circle is parameterized as
$$ \lambda(u) = C + R(\cos(u)x + \sin(u)y) $$
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
$$ C(x,y,z) = x^2 + y^2 - R^2 $$
The positive sense of the circle at any point is in the tangent direction, T, to the curve at the point, where
$$ T = (-C_y,C_x,0) $$
8.9.3.18.2 Entity inheritance
-
- IfcCurve
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlacement
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcSurface
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
8.9.3.18.3 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. |
|
| 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. |
|
| IfcCurve (1) | |||
| * | Dim | IfcDimensionCount |
This attribute is formally derived. The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. |
| IfcConic (1) | |||
| 1 | Position | IfcAxis2Placement |
The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes." |
| Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
| IfcCircle (1) | |||
| 2 | Radius | IfcPositiveLengthMeasure |
The radius of the circle, which shall be greater than zero. |
8.9.3.18.4 Examples
-
Figure 8.9.3.18.B -
Figure 8.9.3.18.C -
Figure 8.9.3.18.D -
Figure 8.9.3.18.E -
Figure 8.9.3.18.F -
Figure 8.9.3.18.G -
Figure 8.9.3.18.H
8.9.3.18.5 Formal representation
ENTITY IfcCircle
SUBTYPE OF (IfcConic);
Radius : IfcPositiveLengthMeasure;
END_ENTITY;