An IfcCircle is a curve consisting of a set of points having equal distance from the center.
Figure 220.127.116.11.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 y = SELF\IfcConic.Position.P z = SELF\IfcConic.Position.P 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
$$ T = (-C_y,C_x,0) $$
|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.
This attribute is formally derived.
The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes."
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The radius of the circle, which shall be greater than zero.
ENTITY IfcCircle SUBTYPE OF (IfcConic); Radius : IfcPositiveLengthMeasure; END_ENTITY;