The curve classes let you implement free-form curves, arcs, and path geometry that contain discontinuities (breaks or kinks in the smoothness of the curve) and that can be joined to form long, continuous curves. TGLoop derives from TGCurve. TGCurve and TGLoop can represent the geometry of all other 2-D geometry classes.
Curves are defined by NonUniform Rational BSplines (NURBs). Non-uniform means that the parameterization of the curve can be changed to allow kinks, gaps, and smooth joins. Rational means that rational polynomials are used to allow exact representations of circles, ellipses, and other conic sections. BSpline stands for Basis spline, which is a spline curve very similar to the Bézier curve, but provides more local control and continuity to give you better curve fitting and modeling.
TGCurve descends from TBaseCurve. TBaseCurve is a template class for TGCurve and TGCurve3D. It contains functionality common to TGCurve and TGCurve3D. The conic curve classes descend from TGCurve and TGCurve3D. The conic curve classes are geometries that you can use to create TGCurve and TGCurve3D geometries in a variety of arcs. See the heading "Conic curve classes" on page 96 for details.
See the heading "Curves, loops, and knot vectors" on page 79 for curve examples and a discussion of discontinuities, curves, control points, and curve continuity.
| TCurve | ApproximateLowerOrder | GetNumberOfKnots | NearestParametric | |
| ApproximateArcLengthReparameterizationCurve | GetNumberOfPoints | RaiseOrder | ||
| ApproximateParameterFromArcLength | GetOrder | Refine | ||
| ArcLength | GetPoint | RefineUniform | ||
| Concatenate | GetPoints | RefineToBeziers | ||
| DragPosition | GetSectionOfCurve | RefineToPinned | ||
| DragTangent | InsertKnot | ReverseDirection | ||
| Evaluate | IsBezier | SetOrder | ||
| GetControlPolyline | IsConsistent | SetPoint | ||
| GetKnot | IsEmpty | SetPoints | ||
| GetKnots | IsPinned | SetKnots | ||
| GetMinParameter | MakeCompatible | SetKnotScheme | ||
| GetMaxParameter | MakeDiscontinuity | |||
| GetNextDiscontinuity | MoveKnot |
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