OCCT

// Created on: 1996-03-12
// Created by: Bruno DUMORTIER
// Copyright (c) 1996-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _GeomConvert_BSplineCurveToBezierCurve_HeaderFile
#define _GeomConvert_BSplineCurveToBezierCurve_HeaderFile

#include <Standard.hxx>
#include <Standard_DefineAlloc.hxx>
#include <Standard_Handle.hxx>

#include <Standard_Integer.hxx>
#include <Geom_BezierCurve.hxx>
#include <NCollection_Array1.hxx>
class Geom_BSplineCurve;
class Geom_BezierCurve;

//! An algorithm to convert a BSpline curve into a series
//! of adjacent Bezier curves.
//! A BSplineCurveToBezierCurve object provides a framework for:
//! -   defining the BSpline curve to be converted
//! -   implementing the construction algorithm, and
//! -   consulting the results.
//! References :
//! Generating the Bezier points of B-spline curves and surfaces
//! (Wolfgang Bohm) CAD volume 13 number 6 november 1981
class GeomConvert_BSplineCurveToBezierCurve
{
public:
  DEFINE_STANDARD_ALLOC

  //! Computes all the data needed to convert the
  //! BSpline curve BasisCurve into a series of adjacent Bezier arcs.
  Standard_EXPORT GeomConvert_BSplineCurveToBezierCurve(
    const occ::handle<Geom_BSplineCurve>& BasisCurve);

  //! Computes all the data needed to convert
  //! the portion of the BSpline curve BasisCurve
  //! limited by the two parameter values U1 and U2 into a series of adjacent Bezier arcs.
  //! The result consists of a series of BasisCurve arcs
  //! limited by points corresponding to knot values of the curve.
  //! Use the available interrogation functions to ascertain
  //! the number of computed Bezier arcs, and then to
  //! construct each individual Bezier curve (or all Bezier curves).
  //! Note: ParametricTolerance is not used.
  //! Raises DomainError if U1 or U2 are out of the parametric bounds of the basis
  //! curve [FirstParameter, LastParameter]. The Tolerance criterion
  //! is ParametricTolerance.
  //! Raised if Abs (U2 - U1) <= ParametricTolerance.
  Standard_EXPORT GeomConvert_BSplineCurveToBezierCurve(
    const occ::handle<Geom_BSplineCurve>& BasisCurve,
    const double                          U1,
    const double                          U2,
    const double                          ParametricTolerance);

  //! Constructs and returns the Bezier curve of index
  //! Index to the table of adjacent Bezier arcs
  //! computed by this algorithm.
  //! This Bezier curve has the same orientation as the
  //! BSpline curve analyzed in this framework.
  //! Exceptions
  //! Standard_OutOfRange if Index is less than 1 or
  //! greater than the number of adjacent Bezier arcs
  //! computed by this algorithm.
  Standard_EXPORT occ::handle<Geom_BezierCurve> Arc(const int Index);

  //! Constructs all the Bezier curves whose data is
  //! computed by this algorithm and loads these curves into the Curves table.
  //! The Bezier curves have the same orientation as the
  //! BSpline curve analyzed in this framework.
  //! Exceptions
  //! Standard_DimensionError if the Curves array was
  //! not created with the following bounds:
  //! -   1 , and
  //! -   the number of adjacent Bezier arcs computed by
  //! this algorithm (as given by the function NbArcs).
  Standard_EXPORT void Arcs(NCollection_Array1<occ::handle<Geom_BezierCurve>>& Curves);

  //! This methode returns the bspline's knots associated to
  //! the converted arcs
  //! Raised if the length of Curves is not equal to
  //! NbArcs + 1
  Standard_EXPORT void Knots(NCollection_Array1<double>& TKnots) const;

  //! Returns the number of BezierCurve arcs.
  //! If at the creation time you have decomposed the basis curve
  //! between the parametric values UFirst, ULast the number of
  //! BezierCurve arcs depends on the number of knots included inside
  //! the interval [UFirst, ULast].
  //! If you have decomposed the whole basis B-spline curve the number
  //! of BezierCurve arcs NbArcs is equal to the number of knots less
  //! one.
  Standard_EXPORT int NbArcs() const;

private:
  occ::handle<Geom_BSplineCurve> myCurve;
};

#endif // _GeomConvert_BSplineCurveToBezierCurve_HeaderFile