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.
A circular arc segment is defined by using the IfcTrimmedCurve with BasisCurve being an IfcCircle.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
$$ T = (-C_y,C_x,0) $$
New entity in IFC1.08.9.3.18.2 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. The inverse attribute LayerAssignments has been added. The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. |
|
| 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. The inverse attribute StyledByItem has been added. |
|
| 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;