8.9.3.18 IfcCircle

AbV ⓘ

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.

axis1 placement — Figure 8.9.3.18.A — Circle layout

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

$λ (u) = C + R (\cos (u) x + \sin (u) y)$

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

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. 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.
	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. IFC2x3-CHANGE The inverse attribute StyledByItem has been added.
IfcCurve (1)
*	Dim	IfcDimensionCount	This attribute is formally derived. `IfcCurveDim(SELF)` 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
IfcCircle (1)
2	Radius	IfcPositiveLengthMeasure	The radius of the circle, which shall be greater than zero.

Table 8.9.3.18.I

8.9.3.18.4 Examples

Figure 8.9.3.18.B

Linear Placement Of Signal
Figure 8.9.3.18.C

Fixed Reference Swept Area Solid
Figure 8.9.3.18.D

Sectioned Solid Horizontal
Figure 8.9.3.18.E

Beam Varying Extrusion Paths
Figure 8.9.3.18.F

Beam Revolved Solid
Figure 8.9.3.18.G

Curve Parameters In Degrees
Figure 8.9.3.18.H

Curve Parameters In Radians

8.9.3.18.5 Formal representation

 ENTITY IfcCircle
 SUBTYPE OF (IfcConic);
	Radius : IfcPositiveLengthMeasure;
END_ENTITY;

8.9.3.18.6 References

IfcConic

	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

	ENTITY IfcCircle
	SUBTYPE OF (IfcConic);
	Radius : IfcPositiveLengthMeasure;
	END_ENTITY;