4.2.2.1.1 Gradient Curve 
Curve geometry based on a 2D horizontal projection as an IfcCompositeCurve   referencing IfcCurveSegment   occurrences. The vertical profile is represented by another independent list of IfcCurveSegment   occurrences.
    The following diagram shows the generic classes and relationships used when applying this concept.
    
G 
 
IfcGradientCurve  
 
 
IfcGradientCurve  
 
 
 
 
      LayerAssignment 
 
 
[0:1] 
 
 
      StyledByItem 
 
 
[0:1] 
 
 
VerticalSegments 
 
 
 
 
1. Segments 
 
 
[1:?] 
 
 
2. SelfIntersect 
 
 
[1:1] 
 
 
3. BaseCurve 
 
 
[1:1] 
 
 
4. EndPoint 
 
 
[0:1] 
 
IfcCompositeCurve  
 
 
IfcCompositeCurve  
 
 
 
 
      LayerAssignment 
 
 
[0:1] 
 
 
      StyledByItem 
 
 
[0:1] 
 
 
CompositeSegments 
 
 
 
 
1. Segments 
 
 
[1:?] 
 
 
2. SelfIntersect 
 
 
[1:1] 
 
IfcGradientCurve :BaseCurve1->IfcCompositeCurve :IfcCompositeCurve0 
 
 
 
IfcCurveSegment_1 
 
 
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] 
 
IfcGradientCurve :Segments1->IfcCurveSegment_1:IfcCurveSegment0 
 
 
 
IfcCurveSegment_0 
 
 
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] 
 
IfcCompositeCurve :Segments1->IfcCurveSegment_0:IfcCurveSegment0 
 
 
 
Arc_Segment 
 
Arc Segment 
 
IfcCurveSegment_1->Arc_Segment 
 
 
 
Clothoid_Transition_Segment 
 
Clothoid Transition Segment 
 
IfcCurveSegment_1->Clothoid_Transition_Segment 
 
 
 
Linear_Segment 
 
Linear Segment 
 
IfcCurveSegment_1->Linear_Segment 
 
 
 
Parabolic_Transition_Segment 
 
Parabolic Transition Segment 
 
IfcCurveSegment_1->Parabolic_Transition_Segment 
 
 
 
IfcCurveSegment_0->Arc_Segment 
 
 
 
Bloss_Transition_Segment 
 
Bloss Transition Segment 
 
IfcCurveSegment_0->Bloss_Transition_Segment 
 
 
 
IfcCurveSegment_0->Clothoid_Transition_Segment 
 
 
 
Cosine_Spiral_Transition_Segment 
 
Cosine Spiral Transition Segment 
 
IfcCurveSegment_0->Cosine_Spiral_Transition_Segment 
 
 
 
Cubic_Transition_Segment 
 
Cubic Transition Segment 
 
IfcCurveSegment_0->Cubic_Transition_Segment 
 
 
 
Helmert_Transition_Segment 
 
Helmert Transition Segment 
 
IfcCurveSegment_0->Helmert_Transition_Segment 
 
 
 
IfcCurveSegment_0->Linear_Segment 
 
 
 
Sine_Spiral_Transition_Segment 
 
Sine Spiral Transition Segment 
 
IfcCurveSegment_0->Sine_Spiral_Transition_Segment 
 
 
 
Viennese_Bend_Transition_Segment 
 
Viennese Bend Transition Segment 
 
IfcCurveSegment_0->Viennese_Bend_Transition_Segment 
 
 
 
 
 Figure 4.2.2.1.1.A