4.2.2.1.4 Cosine Spiral Transition Segment
The cosine spiral transition segment is a special case of a spiral where the curvature rate of change is a cosine function and the terms are dependent on the length L measured from the inflection point. The parameter value is defined as the deflection i.e. bearing angle &Theta.
The values of its individual terms dependent on segment length L:
CosineTerm = L
ConstantTerm = 1
The following diagram shows the generic classes and relationships used when applying this concept.
G
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>
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]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCosineSpiral.htm'>IfcCosineSpiral</a>
IfcCosineSpiral
LayerAssignment
[0:1]
StyledByItem
[0:1]
1. Position
[1:1]
2. CosineTerm
[1:1]
3. ConstantTerm
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:ParentCurve1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCosineSpiral.htm'>IfcCosineSpiral</a>:IfcCosineSpiral0
IfcLengthMeasure_0
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:SegmentStart1->IfcLengthMeasure_0:IfcLengthMeasure0
IfcLengthMeasure_1
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:SegmentLength1->IfcLengthMeasure_1:IfcLengthMeasure0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcLengthMeasure.htm'>IfcLengthMeasure</a>
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCosineSpiral.htm'>IfcCosineSpiral</a>:CosineTerm1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcLengthMeasure.htm'>IfcLengthMeasure</a>:IfcLengthMeasure0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcReal.htm'>IfcReal</a>
IfcReal
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCosineSpiral.htm'>IfcCosineSpiral</a>:ConstantTerm1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcReal.htm'>IfcReal</a>:IfcReal0
Figure 4.2.2.1.4.A