occt/src/Geom/Geom_OffsetCurve.hxx

// Created on: 1993-03-10
// Created by: JCV
// Copyright (c) 1993-1999 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 _Geom_OffsetCurve_HeaderFile
#define _Geom_OffsetCurve_HeaderFile

#include <Standard.hxx>
#include <Standard_Type.hxx>

#include <gp_Dir.hxx>
#include <Standard_Real.hxx>
#include <GeomAbs_Shape.hxx>
#include <Geom_Curve.hxx>
#include <Standard_Boolean.hxx>
#include <Standard_Integer.hxx>
#include <GeomEvaluator_OffsetCurve.hxx>

class Geom_Curve;
class Standard_ConstructionError;
class Standard_RangeError;
class Standard_NoSuchObject;
class Geom_UndefinedDerivative;
class Geom_UndefinedValue;
class gp_Dir;
class gp_Pnt;
class gp_Vec;
class gp_Trsf;
class Geom_Geometry;


class Geom_OffsetCurve;
DEFINE_STANDARD_HANDLE(Geom_OffsetCurve, Geom_Curve)


//! This class implements the basis services for an offset curve
//! in 3D space. The Offset curve in this package can be a self
//! intersecting curve even if the basis curve does not
//! self-intersect. The self intersecting portions are not deleted
//! at the construction time.
//! An offset curve is a curve at constant distance (Offset) from
//! a basis curve in a reference direction V. The offset curve
//! takes its parametrization from the basis curve.
//! The Offset curve is in the direction of the normal N
//! defined with the cross product  T^V, where the vector T
//! is given by the first derivative on the basis curve with
//! non zero length.
//! The distance offset may be positive or negative to indicate the
//! preferred side of the curve :
//! . distance offset >0 => the curve is in the direction of N
//! . distance offset <0 => the curve is in the direction of - N
//!
//! On the Offset curve :
//! Value (U) = BasisCurve.Value(U) + (Offset * (T ^ V)) / ||T ^ V||
//!
//! At any point the Offset direction V must not be parallel to the
//! vector T and the vector T must not have null length else the
//! offset curve is not defined. So the offset curve has not the
//! same continuity as the basis curve.
//!
//! Warnings :
//!
//! In this package we suppose that the continuity of the offset
//! curve is one degree less than the continuity of the basis
//! curve and we don't check that at any point ||T^V|| != 0.0
//!
//! So to evaluate the curve it is better to check that the offset
//! curve is well defined at any point because an exception could
//! be raised. The check is not done in this package at the creation
//! of the offset curve because the control needs the use of an
//! algorithm which cannot be implemented in this package.
//!
//! The OffsetCurve is closed if the first point and the last point
//! are the same (The distance between these two points is lower or
//! equal to the Resolution sea package gp) . The OffsetCurve can be
//! closed even if the basis curve is not closed.
class Geom_OffsetCurve : public Geom_Curve
{

public:

  

  //! C is the basis curve, Offset is the distance between <me> and
  //! the basis curve at any point. V defines the fixed reference
  //! direction (offset direction). If P is a point on the basis
  //! curve and T the first derivative with non zero length
  //! at this point, the corresponding point on the offset curve is
  //! in the direction of the vector-product N = V ^ T   where
  //! N is a unitary vector.
  //! If isNotCheckC0 = TRUE checking if basis curve has C0-continuity
  //! is not made.
  //! Warnings :
  //! In this package the entities are not shared. The OffsetCurve is
  //! built with a copy of the curve C. So when C is modified the
  //! OffsetCurve is not modified
  //!
  //! Raised if the basis curve C is not at least C1.
  //! Warnings :
  //! No check is done to know if ||V^T|| != 0.0 at any point.
  Standard_EXPORT Geom_OffsetCurve(const Handle(Geom_Curve)& C, const Standard_Real Offset, const gp_Dir& V, const Standard_Boolean isNotCheckC0 = Standard_False);
  
  //! Changes the orientation of this offset curve.
  //! As a result:
  //! - the basis curve is reversed,
  //! - the start point of the initial curve becomes the
  //! end point of the reversed curve,
  //! - the end point of the initial curve becomes the
  //! start point of the reversed curve, and
  //! - the first and last parameters are recomputed.
  Standard_EXPORT void Reverse() Standard_OVERRIDE;
  
  //! Computes the parameter on the reversed curve for
  //! the point of parameter U on this offset curve.
  Standard_EXPORT Standard_Real ReversedParameter (const Standard_Real U) const Standard_OVERRIDE;
  
  //! Changes this offset curve by assigning C
  //! as the basis curve from which it is built.
  //! If isNotCheckC0 = TRUE checking if basis curve
  //! has C0-continuity is not made.
  //! Exceptions
  //! Standard_ConstructionError if the curve C is not at least "C1" continuous.
  Standard_EXPORT void SetBasisCurve (const Handle(Geom_Curve)& C, const Standard_Boolean isNotCheckC0 = Standard_False);
  
  //! Changes this offset curve by assigning V as the
  //! reference vector used to compute the offset direction.
  Standard_EXPORT void SetDirection (const gp_Dir& V);
  
  //! Changes this offset curve by assigning D as the offset value.
  Standard_EXPORT void SetOffsetValue (const Standard_Real D);
  
  //! Returns the basis curve of this offset curve.
  //! Note: The basis curve can be an offset curve.
  Standard_EXPORT Handle(Geom_Curve) BasisCurve() const;
  
  //! Returns the global continuity of this offset curve as a
  //! value of the GeomAbs_Shape enumeration.
  //! The degree of continuity of this offset curve is equal
  //! to the degree of continuity of the basis curve minus 1.
  //! Continuity of the Offset curve :
  //! C0 : only geometric continuity,
  //! C1 : continuity of the first derivative all along the Curve,
  //! C2 : continuity of the second derivative all along the Curve,
  //! C3 : continuity of the third derivative all along the Curve,
  //! G1 : tangency continuity all along the Curve,
  //! G2 : curvature continuity all along the Curve,
  //! CN : the order of continuity is infinite.
  //! Warnings :
  //! Returns the continuity of the basis curve - 1.
  //! The offset curve must have a unique offset direction defined
  //! at any point.
  Standard_EXPORT GeomAbs_Shape Continuity() const Standard_OVERRIDE;
  
  //! Returns the reference vector of this offset curve.
  //! Value and derivatives
  //! Warnings :
  //! The exception UndefinedValue or UndefinedDerivative is
  //! raised if it is not possible to compute a unique offset
  //! direction.
  //! If T is the first derivative with not null length and
  //! V the offset direction the relation ||T(U) ^ V|| != 0
  //! must be satisfied to evaluate the offset curve.
  //! No check is done at the creation time and we suppose
  //! in this package that the offset curve is well defined.
  Standard_EXPORT const gp_Dir& Direction() const;
  
  //! Warning! this should not be called
  //! if the basis curve is not at least C1. Nevertheless
  //! if used on portion where the curve is C1, it is OK
  Standard_EXPORT void D0 (const Standard_Real U, gp_Pnt& P) const Standard_OVERRIDE;
  
  //! Warning! this should not be called
  //! if the continuity of the basis curve is not C2.
  //! Nevertheless, it's OK to use it  on portion
  //! where the curve is C2
  Standard_EXPORT void D1 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1) const Standard_OVERRIDE;
  
  //! Warning! this should not be called
  //! if the continuity of the basis curve is not C3.
  //! Nevertheless, it's OK to use it  on portion
  //! where the curve is C3
  Standard_EXPORT void D2 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1, gp_Vec& V2) const Standard_OVERRIDE;
  
  Standard_EXPORT void D3 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1, gp_Vec& V2, gp_Vec& V3) const Standard_OVERRIDE;
  

  //! The returned vector gives the value of the derivative
  //! for the order of derivation N.
  //!
  //! The following functions compute the value and derivatives
  //! on the offset curve and returns the derivatives on the
  //! basis curve too.
  //! The computation of the value and derivatives on the basis
  //! curve are used to evaluate the offset curve
  //!
  //! Warning:
  //! The exception UndefinedValue or UndefinedDerivative is
  //! raised if it is not possible to compute a unique offset
  //! direction.
  //! Raised if N < 1.
  Standard_EXPORT gp_Vec DN (const Standard_Real U, const Standard_Integer N) const Standard_OVERRIDE;

  //! Returns the value of the first parameter of this
  //! offset curve. The first parameter corresponds to the
  //! start point of the curve.
  //! Note: the first and last parameters of this offset curve
  //! are also the ones of its basis curve.
  Standard_EXPORT Standard_Real FirstParameter() const Standard_OVERRIDE;

  //! Returns the value of the last parameter of this
  //! offset curve. The last parameter
  //! corresponds to the end point.
  //! Note: the first and last parameters of this offset curve
  //! are also the ones of its basis curve.
  Standard_EXPORT Standard_Real LastParameter() const Standard_OVERRIDE;
  
  //! Returns the offset value of this offset curve.
  Standard_EXPORT Standard_Real Offset() const;
  
  //! Returns True if the distance between the start point
  //! and the end point of the curve is lower or equal to
  //! Resolution from package gp.
  Standard_EXPORT Standard_Boolean IsClosed() const Standard_OVERRIDE;
  
  //! Returns true if the degree of continuity of the basis
  //! curve of this offset curve is at least N + 1.
  //! This method answer True if the continuity of the basis curve
  //! is N + 1.  We suppose in this class that a normal direction
  //! to the basis curve (used to compute the offset curve) is
  //! defined at any point on the basis curve.
  //! Raised if N < 0.
  Standard_EXPORT Standard_Boolean IsCN (const Standard_Integer N) const Standard_OVERRIDE;
  
  //! Returns true if this offset curve is periodic, i.e. if the
  //! basis curve of this offset curve is periodic.
  Standard_EXPORT Standard_Boolean IsPeriodic() const Standard_OVERRIDE;
  
  //! Returns the period of this offset curve, i.e. the period
  //! of the basis curve of this offset curve.
  //! Exceptions
  //! Standard_NoSuchObject if the basis curve is not periodic.
  Standard_EXPORT virtual Standard_Real Period() const Standard_OVERRIDE;
  
  //! Applies the transformation T to this offset curve.
  //! Note: the basis curve is also modified.
  Standard_EXPORT void Transform (const gp_Trsf& T) Standard_OVERRIDE;
  
  //! Returns the  parameter on the  transformed  curve for
  //! the transform of the point of parameter U on <me>.
  //! me->Transformed(T)->Value(me->TransformedParameter(U,T))
  //! is the same point as
  //! me->Value(U).Transformed(T)
  //! This methods calls the basis curve method.
  Standard_EXPORT virtual Standard_Real TransformedParameter (const Standard_Real U, const gp_Trsf& T) const Standard_OVERRIDE;
  
  //! Returns a  coefficient to compute the parameter on
  //! the transformed  curve  for  the transform  of the
  //! point on <me>.
  //!
  //! Transformed(T)->Value(U * ParametricTransformation(T))
  //! is the same point as
  //! Value(U).Transformed(T)
  //! This methods calls the basis curve method.
  Standard_EXPORT virtual Standard_Real ParametricTransformation (const gp_Trsf& T) const Standard_OVERRIDE;
  
  //! Creates a new object which is a copy of this offset curve.
  Standard_EXPORT Handle(Geom_Geometry) Copy() const Standard_OVERRIDE;
  
  //! Returns continuity of the basis curve.
  Standard_EXPORT GeomAbs_Shape GetBasisCurveContinuity() const;




  DEFINE_STANDARD_RTTIEXT(Geom_OffsetCurve,Geom_Curve)

protected:




private:


  Handle(Geom_Curve) basisCurve;
  gp_Dir direction;
  Standard_Real offsetValue;
  GeomAbs_Shape myBasisCurveContinuity;
  Handle(GeomEvaluator_OffsetCurve) myEvaluator;

};







#endif // _Geom_OffsetCurve_HeaderFile