IFC 4.3.0.1 (IFC4X3_TC1)

4.7.1.2.8 Parabolic Transition Segment

The parabolic transition segment is modelled with IfcPolynomialCurve with certain restrictions. The size of the attribute CoefficientsY is restricted to 3. The quadratic term is on position 3. In general, the CoefficietsX size would be restricted to 2 and values specified as [0, 1]. This produces the following result:

y = CoefficientsX[3]*x², where other values in CoefficientsY are 0.

The following diagram shows the generic classes and relationships used when applying this concept.

G IfcCurveSegment IfcCurveSegment      LayerAssignment [0:1]      StyledByItem [0:1] 1. Transition [1:1]      UsingCurves [1:?] 2. Placement [1:1] 3. SegmentStart [1:1] 4. SegmentLength [1:1] 5. ParentCurve [1:1] IfcPolynomialCurve IfcPolynomialCurve      LayerAssignment [0:1]      StyledByItem [0:1] 1. Position [1:1] 2. CoefficientsX [2:?] 3. CoefficientsY [2:?] 4. CoefficientsZ [2:?] IfcCurveSegment:ParentCurve1->IfcPolynomialCurve:IfcPolynomialCurve0 IfcReal_0 IfcReal IfcPolynomialCurve:CoefficientsX1->IfcReal_0:IfcReal0 IfcReal_1 IfcReal IfcPolynomialCurve:CoefficientsY1->IfcReal_1:IfcReal0
Figure 4.7.1.2.8.A