| Item | SPF | XML | Change | Description | IFC4x3_RC2 to IFC4x3_RC3 |
|---|---|---|---|---|
| IfcThirdOrderPolynomialSpiral | MODIFIED | Name changed from IfcBlossCurve to IfcThirdOrderPolynomialSpiral. | ||
| Position | MODIFIED | Instantiation changed to OPTIONAL. | ||
| QubicTerm | X | X | MODIFIED | Name changed from CurveLength to QubicTerm. Type changed from IfcPositiveLengthMeasure to IfcLengthMeasure. |
| QuadraticTerm | X | X | MODIFIED | Name changed from Radius to QuadraticTerm. Type changed from IfcPositiveLengthMeasure to IfcLengthMeasure. Instantiation changed to OPTIONAL. |
| LinearTerm | ADDED | IFC4x3_RC3 to IFC4x3_RC4 | ||
| IfcThirdOrderPolynomialSpiral | ||||
| CubicTerm | X | MODIFIED | Name changed from QubicTerm to CubicTerm. | |
| ConstantTerm | ADDED |
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 = ContantTermand the third order polynomial spiral is parameterized as:
where:
and the parametric range is: -∞ < u < ∞.
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| 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. | X | |
| 3 | QuadraticTerm | IfcLengthMeasure | ? | The constant that defines the quadratic term in the equation which defines the relation between curvature and arc length for the curve. | X |
| 4 | LinearTerm | IfcLengthMeasure | ? | The constant that defines the linear term in the equation which defines the relation between curvature and arc length for the curve. | X |
| 5 | ConstantTerm | IfcLengthMeasure | ? | The constant that defines the constant term in the equation which defines the relation between curvature and arc length for the curve. | X |
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| 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.
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. | 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.
IFC2x3 CHANGE The inverse attribute StyledByItem has been added. | X | |
| IfcGeometricRepresentationItem | |||||
| IfcCurve | |||||
| Dim :=IfcCurveDim(SELF) | IfcDimensionCount | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | ||
| IfcSpiral | |||||
| 1 | Position | IfcAxis2Placement | X | ||
| IfcThirdOrderPolynomialSpiral | |||||
| 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. | X | |
| 3 | QuadraticTerm | IfcLengthMeasure | ? | The constant that defines the quadratic term in the equation which defines the relation between curvature and arc length for the curve. | X |
| 4 | LinearTerm | IfcLengthMeasure | ? | The constant that defines the linear term in the equation which defines the relation between curvature and arc length for the curve. | X |
| 5 | ConstantTerm | IfcLengthMeasure | ? | The constant that defines the constant term in the equation which defines the relation between curvature and arc length for the curve. | X |
<xs:element name="IfcThirdOrderPolynomialSpiral" type="ifc:IfcThirdOrderPolynomialSpiral" substitutionGroup="ifc:IfcSpiral" nillable="true"/>
<xs:complexType name="IfcThirdOrderPolynomialSpiral">
<xs:complexContent>
<xs:extension base="ifc:IfcSpiral">
<xs:attribute name="CubicTerm" type="ifc:IfcLengthMeasure" use="optional"/>
<xs:attribute name="QuadraticTerm" type="ifc:IfcLengthMeasure" use="optional"/>
<xs:attribute name="LinearTerm" type="ifc:IfcLengthMeasure" use="optional"/>
<xs:attribute name="ConstantTerm" type="ifc:IfcLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
ENTITY IfcThirdOrderPolynomialSpiral
SUBTYPE OF (IfcSpiral);
CubicTerm : IfcLengthMeasure;
QuadraticTerm : OPTIONAL IfcLengthMeasure;
LinearTerm : OPTIONAL IfcLengthMeasure;
ConstantTerm : OPTIONAL IfcLengthMeasure;
END_ENTITY;
EXPRESS-G diagram
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