OCCT

// Created on: 1992-01-30
// Created by: Didier PIFFAULT
// Copyright (c) 1992-1999 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 _TopTrans_CurveTransition_HeaderFile
#define _TopTrans_CurveTransition_HeaderFile

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

#include <gp_Dir.hxx>
#include <TopAbs_Orientation.hxx>
#include <TopAbs_State.hxx>

//! This algorithm is used to compute the transition
//! of a Curve intersecting a curvilinear boundary.
//!
//! The geometric elements are described locally at
//! the intersection point by a second order
//! development.
//!
//! The curve is described by the intersection point,
//! the tangent vector and the curvature.
//!
//! The boundary is described by a set of curve
//! elements, a curve element is either :
//!
//! - A curve.
//!
//! - A curve and an orientation called a half-curve,
//! the boundary of the curve is before or after the
//! intersection point depending on the orientation.
class TopTrans_CurveTransition
{
public:
  DEFINE_STANDARD_ALLOC

  //! Create an empty Curve Transition.
  Standard_EXPORT TopTrans_CurveTransition();

  //! Initialize a Transition with the local description
  //! of a Curve.
  Standard_EXPORT void Reset(const gp_Dir& Tgt, const gp_Dir& Norm, const double Curv);

  //! Initialize a Transition with the local description of a straight line.
  Standard_EXPORT void Reset(const gp_Dir& Tgt);

  //! Add a curve element to the boundary. If Or is
  //! REVERSED the curve is before the intersection,
  //! else if Or is FORWARD the curv is after the
  //! intersection and if Or is INTERNAL the
  //! intersection is in the middle of the curv.
  Standard_EXPORT void Compare(const double             Tole,
                               const gp_Dir&            Tang,
                               const gp_Dir&            Norm,
                               const double             Curv,
                               const TopAbs_Orientation S,
                               const TopAbs_Orientation Or);

  //! returns the state of the curve before the
  //! intersection, this is the position relative to the
  //! boundary of a point very close to the intersection
  //! on the negative side of the tangent.
  Standard_EXPORT TopAbs_State StateBefore() const;

  //! returns the state of the curve after the
  //! intersection, this is the position relative to the
  //! boundary of a point very close to the intersection
  //! on the positive side of the tangent.
  Standard_EXPORT TopAbs_State StateAfter() const;

private:
  //! Compare two curvature and return true if N1,C1 is
  //! before N2,C2 in the edge orientation
  Standard_EXPORT bool IsBefore(const double  Tole,
                                const double  Angl,
                                const gp_Dir& Nor1,
                                const double  Cur1,
                                const gp_Dir& Nor2,
                                const double  Cur2) const;

  //! Compare two angles at tolerance Tole
  Standard_EXPORT int Compare(const double Ang1, const double Ang2, const double Tole) const;

  gp_Dir             myTgt;
  gp_Dir             myNorm;
  double             myCurv;
  bool               Init;
  gp_Dir             TgtFirst;
  gp_Dir             NormFirst;
  double             CurvFirst;
  TopAbs_Orientation TranFirst;
  gp_Dir             TgtLast;
  gp_Dir             NormLast;
  double             CurvLast;
  TopAbs_Orientation TranLast;
};

#endif // _TopTrans_CurveTransition_HeaderFile