include/opencascade/Law_BSplineKnotSplitting.hxx

0001 // Created on: 1997-01-17
0002 // Created by: Philippe MANGIN
0003 // Copyright (c) 1997-1999 Matra Datavision
0004 // Copyright (c) 1999-2014 OPEN CASCADE SAS
0005 //
0006 // This file is part of Open CASCADE Technology software library.
0007 //
0008 // This library is free software; you can redistribute it and/or modify it under
0009 // the terms of the GNU Lesser General Public License version 2.1 as published
0010 // by the Free Software Foundation, with special exception defined in the file
0011 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
0012 // distribution for complete text of the license and disclaimer of any warranty.
0013 //
0014 // Alternatively, this file may be used under the terms of Open CASCADE
0015 // commercial license or contractual agreement.
0016
0017 #ifndef _Law_BSplineKnotSplitting_HeaderFile
0018 #define _Law_BSplineKnotSplitting_HeaderFile
0019
0020 #include <Standard.hxx>
0021 #include <Standard_DefineAlloc.hxx>
0022 #include <Standard_Handle.hxx>
0023
0024 #include <Standard_Integer.hxx>
0025 #include <NCollection_Array1.hxx>
0026 #include <NCollection_HArray1.hxx>
0027 class Law_BSpline;
0028
0029 //! For a B-spline curve the discontinuities are localised at the
0030 //! knot values and between two knots values the B-spline is
0031 //! infinitely continuously differentiable.
0032 //! At a knot of range index the continuity is equal to:
0033 //! Degree - Mult (Index) where Degree is the degree of the
0034 //! basis B-spline functions and Mult the multiplicity of the knot
0035 //! of range Index.
0036 //! If for your computation you need to have B-spline curves with a
0037 //! minima of continuity it can be interesting to know between which
0038 //! knot values, a B-spline curve arc, has a continuity of given order.
0039 //! This algorithm computes the indexes of the knots where you should
0040 //! split the curve, to obtain arcs with a constant continuity given
0041 //! at the construction time. The splitting values are in the range
0042 //! [FirstUKnotValue, LastUKnotValue] (See class B-spline curve from
0043 //! package Geom).
0044 //! If you just want to compute the local derivatives on the curve you
0045 //! don't need to create the B-spline curve arcs, you can use the
0046 //! functions LocalD1, LocalD2, LocalD3, LocalDN of the class
0047 //! BSplineCurve.
0048 class Law_BSplineKnotSplitting
0049 {
0050 public:
0051   DEFINE_STANDARD_ALLOC
0052
0053   //! Locates the knot values which correspond to the segmentation of
0054   //! the curve into arcs with a continuity equal to ContinuityRange.
0055   //!
0056   //! Raised if ContinuityRange is not greater or equal zero.
0057   Standard_EXPORT Law_BSplineKnotSplitting(const occ::handle<Law_BSpline>& BasisLaw,
0058                                            const int                       ContinuityRange);
0059
0060   //! Returns the number of knots corresponding to the splitting.
0061   Standard_EXPORT int NbSplits() const;
0062
0063   //! Returns the indexes of the BSpline curve knots corresponding to
0064   //! the splitting.
0065   //!
0066   //! Raised if the length of SplitValues is not equal to NbSPlit.
0067   Standard_EXPORT void Splitting(NCollection_Array1<int>& SplitValues) const;
0068
0069   //! Returns the index of the knot corresponding to the splitting
0070   //! of range Index.
0071   //!
0072   //! Raised if Index < 1 or Index > NbSplits
0073   Standard_EXPORT int SplitValue(const int Index) const;
0074
0075 private:
0076   occ::handle<NCollection_HArray1<int>> splitIndexes;
0077 };
0078
0079 #endif // _Law_BSplineKnotSplitting_HeaderFile