Ellipse | |
Ellipse | |
Ellipse |
An IfcEllipse is a curve consisting of a set of points whose distances to two fixed points add to the same constant.
The inherited SELF\IfcConic.Position.Location is the center of the IfcEllipse, and the inherited SELF\IfcConic.Position.Position.P[1] is the direction of the SemiAxis1.
Definition of the IfcEllipse within the a three-dimensional position coordinate system is shown in Figure 342. It is placed within the object coordinate system of an element of which it is a representation. |
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Figure 342 — Ellipse placement and parameterization |
NOTE An elliptical arc segment is defined by using the IfcTrimmedCurve with BasisCurve
NOTE Definition according to ISO/CD 10303-42:1992
An ellipse is a conic section defined by the lengths of the semi-major and semi-minor diameters and the position (center or mid point of the line joining the foci) and orientation of the curve. Interpretation of the data shall be as follows:C = position.location
x = position.p[1]
y = position.p[2]
z = position.p[3]
R1 = semi axis 1
R2 = semi axis 2and the ellipse is parameterized as:
The parameterization range is 0 ≤ u <≤ 2π (0 ≤ u ≤ 360 degree). In the placement coordinate system defined above, the ellipse is the equation C = 0, where
The positive sense of the ellipse at any point is in the tangent direction, T, to the curve at the point, where
NOTE Entity adapted from ellipse defined in ISO 10303-42
HISTORY New entity in IFC1.0
# | Attribute | Type | Cardinality | Description | C |
---|---|---|---|---|---|
2 | SemiAxis1 | IfcPositiveLengthMeasure | [1:1] | The first radius of the ellipse which shall be positive. Placement.Axes[1] gives the direction of the SemiAxis1. | X |
3 | SemiAxis2 | IfcPositiveLengthMeasure | [1:1] | The second radius of the ellipse which shall be positive. | X |
# | Attribute | Type | Cardinality | Description | C |
---|---|---|---|---|---|
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. | 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. | X | |
IfcGeometricRepresentationItem | |||||
IfcCurve | |||||
Dim :=IfcCurveDim(SELF) | IfcDimensionCount | [1:1] | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | |
IfcConic | |||||
1 | Position | IfcAxis2Placement | [1:1] | The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes." | X |
IfcEllipse | |||||
2 | SemiAxis1 | IfcPositiveLengthMeasure | [1:1] | The first radius of the ellipse which shall be positive. Placement.Axes[1] gives the direction of the SemiAxis1. | X |
3 | SemiAxis2 | IfcPositiveLengthMeasure | [1:1] | The second radius of the ellipse which shall be positive. | X |
<xs:element name="IfcEllipse" type="ifc:IfcEllipse" substitutionGroup="ifc:IfcConic" nillable="true"/>
<xs:complexType name="IfcEllipse">
<xs:complexContent>
<xs:extension base="ifc:IfcConic">
<xs:attribute name="SemiAxis1" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
<xs:attribute name="SemiAxis2" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
ENTITY IfcEllipse
SUBTYPE OF (IfcConic);
SemiAxis1 : IfcPositiveLengthMeasure;
SemiAxis2 : IfcPositiveLengthMeasure;
END_ENTITY;