Loops are closed curves for drawing filled curves. Loops derive from curves. TGCurve and TGLoop can represent the geometry of all other 2-D geometry classes because they have constructors that accept any 2-D geometry. To fill a loop, use one of the fill algorithms described under the heading "Fill algorithm for loops and polygons" on page 76.Discontinuities (breaks) in the curves of a loop are closed when the loop is drawn. For hit detection, the direction of each loop segment is used to determine whether a point is inside or outside the loop. For example, the letter "O" can be created from two concentric circles with the inner circle running in the opposite parametric direction from the outer circle. This way, points that lie between the two circles will be found to be on the letter.
See the heading "Curves, loops, and knot vectors" on page 79 for loop examples and for a discussion of discontinuities, curves, control points, and curve continuity.
| TLoop | ApproximateLowerOrder | GetPoints | NearestParametric | |
| ApproximateArcLengthReparameterizationCurve | GetMinParameter | RaiseOrder | ||
| ApproximateParameterFromArcLength | GetMaxParameter | Refine | ||
| ArcLength | GetNextDiscontinuity | RefineUniform | ||
| Concatenate | GetNumberOfPoints | RefineToBeziers | ||
| DragPosition | GetNumberOfKnots | RefineToPinned | ||
| DragTangent | GetSectionOfCurve | ReverseDirection | ||
| Evaluate | InsertKnot | SetEOFill | ||
| GetControlPolyline | IsBezier | SetOrder | ||
| GetEOFill | IsConsistent | SetPoint | ||
| GetKnot | IsPinned | SetPoints | ||
| GetKnots | IsEmpty | SetKnotScheme | ||
| GetOrder | IsEqual | SetKnots | ||
| GetPoint | MoveKnot | StartIndex |
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