8.9.3.72 IfcThirdOrderPolynomialSpiral
8.9.3.72.1 Semantic definition
The IfcThirdOrderPolynomialSpiral is a specialization of IfcSpiral. The curvature κ and radius of the curvature ρ, at any point of the curve, are related to the arc length s by the third order formulae:
Interpretation of the parameters:
C = SELF\IfcSpiral.Position.Location x = SELF\IfcSpiral.Position.P[1] y = SELF\IfcSpiral.Position.P[2] A3 = CubicTerm A2 = QuadraticTerm A1 = LinearTerm A0 = ContantTerm
and the third order polynomial spiral is parameterized as:
where:
and the parametric range is: -∞ < u < ∞.
8.9.3.72.2 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
8.9.3.72.3 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. |
IfcSpiral (1) | |||
1 | Position | IfcAxis2Placement |
No description available. |
Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
IfcThirdOrderPolynomialSpiral (4) | |||
2 | CubicTerm | IfcLengthMeasure |
The constant that defines the cubic term in the equation which defines the relation between curvature and arc length for the curve. |
3 | QuadraticTerm | OPTIONAL IfcLengthMeasure |
The constant that defines the quadratic term in the equation which defines the relation between curvature and arc length for the curve. |
4 | LinearTerm | OPTIONAL IfcLengthMeasure |
The constant that defines the linear term in the equation which defines the relation between curvature and arc length for the curve. |
5 | ConstantTerm | OPTIONAL IfcLengthMeasure |
The constant that defines the constant term in the equation which defines the relation between curvature and arc length for the curve. |
8.9.3.72.4 Formal representation
ENTITY IfcThirdOrderPolynomialSpiral
SUBTYPE OF (IfcSpiral);
CubicTerm : IfcLengthMeasure;
QuadraticTerm : OPTIONAL IfcLengthMeasure;
LinearTerm : OPTIONAL IfcLengthMeasure;
ConstantTerm : OPTIONAL IfcLengthMeasure;
END_ENTITY;