OCCT 8.0.1
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    Open CASCADE Technology Reference Manual 8.0.1
    Geom2d_Curve Class Referenceabstract

    The abstract class Curve describes the common behavior of curves in 2D space. The Geom2d package provides numerous concrete classes of derived curves, including lines, circles, conics, Bezier or BSpline curves, etc. The main characteristic of these curves is that they are parameterized. The Geom2d_Curve class shows: More...

    #include <Geom2d_Curve.hxx>

    Inheritance diagram for Geom2d_Curve:

    Data Structures

    struct  ResD1
     Result of D1 evaluation: point and first derivative. More...
    struct  ResD2
     Result of D2 evaluation: point and first two derivatives. More...
    struct  ResD3
     Result of D3 evaluation: point and first three derivatives. More...

    Public Member Functions

    virtual void Reverse ()=0
     Changes the direction of parametrization of <me>. The "FirstParameter" and the "LastParameter" are not changed but the orientation of the curve is modified. If the curve is bounded the StartPoint of the initial curve becomes the EndPoint of the reversed curve and the EndPoint of the initial curve becomes the StartPoint of the reversed curve.
    virtual double ReversedParameter (const double U) const =0
     Computes the parameter on the reversed curve for the point of parameter U on this curve. Note: The point of parameter U on this curve is identical to the point of parameter ReversedParameter(U) on the reversed curve.
    virtual double TransformedParameter (const double U, const gp_Trsf2d &T) const
     Computes the parameter on the curve transformed by T for the point of parameter U on this curve. Note: this function generally returns U but it can be redefined (for example, on a line).
    virtual double ParametricTransformation (const gp_Trsf2d &T) const
     Returns the coefficient required to compute the parametric transformation of this curve when transformation T is applied. This coefficient is the ratio between the parameter of a point on this curve and the parameter of the transformed point on the new curve transformed by T. Note: this function generally returns 1. but it can be redefined (for example, on a line).
    occ::handle< Geom2d_Curve > Reversed () const
     Creates a reversed duplicate Changes the orientation of this curve. The first and last parameters are not changed, but the parametric direction of the curve is reversed. If the curve is bounded:
    virtual double FirstParameter () const =0
     Returns the value of the first parameter. Warnings : It can be RealFirst or RealLast from package Standard if the curve is infinite.
    virtual double LastParameter () const =0
     Value of the last parameter. Warnings : It can be RealFirst or RealLast from package Standard if the curve is infinite.
    virtual bool IsClosed () const =0
     Returns true if the curve is closed. Examples : Some curves such as circle are always closed, others such as line are never closed (by definition). Some Curves such as OffsetCurve can be closed or not. These curves are considered as closed if the distance between the first point and the last point of the curve is lower or equal to the Resolution from package gp which is a fixed criterion independent of the application.
    virtual bool IsPeriodic () const =0
     Returns true if the parameter of the curve is periodic. It is possible only if the curve is closed and if the following relation is satisfied : for each parametric value U the distance between the point P(u) and the point P (u + T) is lower or equal to Resolution from package gp, T is the period and must be a constant. There are three possibilities : . the curve is never periodic by definition (SegmentLine) . the curve is always periodic by definition (Circle) . the curve can be defined as periodic (BSpline). In this case a function SetPeriodic allows you to give the shape of the curve. The general rule for this case is : if a curve can be periodic or not the default periodicity set is non periodic and you have to turn (explicitly) the curve into a periodic curve if you want the curve to be periodic.
    virtual double Period () const
     Returns the period of this curve. raises if the curve is not periodic.
    virtual GeomAbs_Shape Continuity () const =0
     It is the global continuity of the 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.
    virtual bool IsCN (const int N) const =0
     Returns true if the degree of continuity of this curve is at least N. Exceptions Standard_RangeError if N is less than 0.
    virtual gp_Pnt2d EvalD0 (const double U) const =0
     Computes the point of parameter U. Raises an exception on failure.
    virtual ResD1 EvalD1 (const double U) const =0
     Computes the point and first derivative at parameter U. Raises an exception if the curve continuity is not C1.
    virtual ResD2 EvalD2 (const double U) const =0
     Computes the point and first two derivatives at parameter U. Raises an exception if the curve continuity is not C2.
    virtual ResD3 EvalD3 (const double U) const =0
     Computes the point and first three derivatives at parameter U. Raises an exception if the curve continuity is not C3.
    virtual gp_Vec2d EvalDN (const double U, const int N) const =0
     Computes the Nth derivative at parameter U. Raises an exception if the curve continuity is not CN, or N < 1.
    void D0 (const double U, gp_Pnt2d &P) const
     Returns in P the point of parameter U.
    void D1 (const double U, gp_Pnt2d &P, gp_Vec2d &V1) const
     Returns the point P of parameter U and the first derivative V1.
    void D2 (const double U, gp_Pnt2d &P, gp_Vec2d &V1, gp_Vec2d &V2) const
     Returns the point P of parameter U, the first and second derivatives V1 and V2.
    void D3 (const double U, gp_Pnt2d &P, gp_Vec2d &V1, gp_Vec2d &V2, gp_Vec2d &V3) const
     Returns the point P of parameter U, the first, the second and the third derivative.
    gp_Vec2d DN (const double U, const int N) const
     Computes the Nth derivative vector.
    gp_Pnt2d Value (const double U) const
     Computes the point of parameter U on <me>. Implemented with D0.
    void DumpJson (Standard_OStream &theOStream, int theDepth=-1) const override
     Dumps the content of me into the stream.
    Public Member Functions inherited from Geom2d_Geometry
    void Mirror (const gp_Pnt2d &P)
     Performs the symmetrical transformation of a Geometry with respect to the point P which is the center of the symmetry and assigns the result to this geometric object.
    void Mirror (const gp_Ax2d &A)
     Performs the symmetrical transformation of a Geometry with respect to an axis placement which is the axis of the symmetry.
    void Rotate (const gp_Pnt2d &P, const double Ang)
     Rotates a Geometry. P is the center of the rotation. Ang is the angular value of the rotation in radians.
    void Scale (const gp_Pnt2d &P, const double S)
     Scales a Geometry. S is the scaling value.
    void Translate (const gp_Vec2d &V)
     Translates a Geometry. V is the vector of the translation.
    void Translate (const gp_Pnt2d &P1, const gp_Pnt2d &P2)
     Translates a Geometry from the point P1 to the point P2.
    virtual void Transform (const gp_Trsf2d &T)=0
     Transformation of a geometric object. This transformation can be a translation, a rotation, a symmetry, a scaling or a complex transformation obtained by combination of the previous elementaries transformations. (see class Transformation of the package Geom2d). The following transformations have the same properties as the previous ones but they don't modified the object itself. A copy of the object is returned.
    occ::handle< Geom2d_Geometry > Mirrored (const gp_Pnt2d &P) const
    occ::handle< Geom2d_Geometry > Mirrored (const gp_Ax2d &A) const
    occ::handle< Geom2d_Geometry > Rotated (const gp_Pnt2d &P, const double Ang) const
    occ::handle< Geom2d_Geometry > Scaled (const gp_Pnt2d &P, const double S) const
    occ::handle< Geom2d_Geometry > Transformed (const gp_Trsf2d &T) const
    occ::handle< Geom2d_Geometry > Translated (const gp_Vec2d &V) const
    occ::handle< Geom2d_Geometry > Translated (const gp_Pnt2d &P1, const gp_Pnt2d &P2) const
    virtual occ::handle< Geom2d_Geometry > Copy () const =0
    Public Member Functions inherited from Standard_Transient
     Standard_Transient ()
     Empty constructor.
     Standard_Transient (const Standard_Transient &)
     Copy constructor – does nothing.
    Standard_Transient & operator= (const Standard_Transient &)
     Assignment operator, needed to avoid copying reference counter.
    virtual ~Standard_Transient ()=default
     Destructor must be virtual.
    virtual const opencascade::handle< Standard_Type > & DynamicType () const
     Returns a type descriptor about this object.
    bool IsInstance (const opencascade::handle< Standard_Type > &theType) const
     Returns a true value if this is an instance of Type.
    bool IsInstance (const char *const theTypeName) const
     Returns a true value if this is an instance of TypeName.
    bool IsKind (const opencascade::handle< Standard_Type > &theType) const
     Returns true if this is an instance of Type or an instance of any class that inherits from Type. Note that multiple inheritance is not supported by OCCT RTTI mechanism.
    bool IsKind (const char *const theTypeName) const
     Returns true if this is an instance of TypeName or an instance of any class that inherits from TypeName. Note that multiple inheritance is not supported by OCCT RTTI mechanism.
    Standard_Transient * This () const
     Returns non-const pointer to this object (like const_cast). For protection against creating handle to objects allocated in stack or call from constructor, it will raise exception Standard_ProgramError if reference counter is zero.
    int GetRefCount () const noexcept
     Get the reference counter of this object.
    void IncrementRefCounter () noexcept
     Increments the reference counter of this object. Uses relaxed memory ordering since incrementing only requires atomicity, not synchronization with other memory operations.
    int DecrementRefCounter () noexcept
     Decrements the reference counter of this object; returns the decremented value. Uses release ordering for the decrement to ensure all writes to the object are visible before the count reaches zero. An acquire fence is added only when the count reaches zero, ensuring proper synchronization before deletion. This is more efficient than using acq_rel for every decrement.
    virtual void Delete () const
     Memory deallocator for transient classes.

    Additional Inherited Members

    typedef void base_type
     Returns a type descriptor about this object.
    static constexpr const char * get_type_name ()
     Returns a type descriptor about this object.
    static const opencascade::handle< Standard_Type > & get_type_descriptor ()
     Returns type descriptor of Standard_Transient class.

    Detailed Description

    The abstract class Curve describes the common behavior of curves in 2D space. The Geom2d package provides numerous concrete classes of derived curves, including lines, circles, conics, Bezier or BSpline curves, etc. The main characteristic of these curves is that they are parameterized. The Geom2d_Curve class shows:

    • how to work with the parametric equation of a curve in order to calculate the point of parameter u, together with the vector tangent and the derivative vectors of order 2, 3,..., N at this point;
    • how to obtain general information about the curve (for example, level of continuity, closed characteristics, periodicity, bounds of the parameter field);
    • how the parameter changes when a geometric transformation is applied to the curve or when the orientation of the curve is inverted. All curves must have a geometric continuity: a curve is at least "C0". Generally, this property is checked at the time of construction or when the curve is edited. Where this is not the case, the documentation explicitly states so. Warning The Geom2d package does not prevent the construction of curves with null length or curves which self-intersect.

    Member Function Documentation

    ◆ Continuity()

    virtual GeomAbs_Shape Geom2d_Curve::Continuity ( ) const
    pure virtual

    It is the global continuity of the 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.

    Implemented in Bisector_BisecAna, Bisector_BisecCC, Bisector_BisecPC, Geom2d_BezierCurve, Geom2d_BSplineCurve, Geom2d_Conic, Geom2d_Line, Geom2d_OffsetCurve, Geom2d_TrimmedCurve, Geom2dEval_AHTBezierCurve, Geom2dEval_ArchimedeanSpiralCurve, Geom2dEval_CircleInvoluteCurve, Geom2dEval_LogarithmicSpiralCurve, Geom2dEval_SineWaveCurve, and Geom2dEval_TBezierCurve.

    ◆ D0()

    void Geom2d_Curve::D0 ( const double U,
    gp_Pnt2d & P ) const
    inline

    Returns in P the point of parameter U.

    ◆ D1()

    void Geom2d_Curve::D1 ( const double U,
    gp_Pnt2d & P,
    gp_Vec2d & V1 ) const
    inline

    Returns the point P of parameter U and the first derivative V1.

    ◆ D2()

    void Geom2d_Curve::D2 ( const double U,
    gp_Pnt2d & P,
    gp_Vec2d & V1,
    gp_Vec2d & V2 ) const
    inline

    Returns the point P of parameter U, the first and second derivatives V1 and V2.

    ◆ D3()

    void Geom2d_Curve::D3 ( const double U,
    gp_Pnt2d & P,
    gp_Vec2d & V1,
    gp_Vec2d & V2,
    gp_Vec2d & V3 ) const
    inline

    Returns the point P of parameter U, the first, the second and the third derivative.

    ◆ DN()

    gp_Vec2d Geom2d_Curve::DN ( const double U,
    const int N ) const
    inline

    Computes the Nth derivative vector.

    ◆ DumpJson()

    ◆ EvalD0()

    ◆ EvalD1()

    ◆ EvalD2()

    virtual ResD2 Geom2d_Curve::EvalD2 ( const double U) const
    nodiscardpure virtual

    ◆ EvalD3()

    virtual ResD3 Geom2d_Curve::EvalD3 ( const double U) const
    nodiscardpure virtual

    ◆ EvalDN()

    virtual gp_Vec2d Geom2d_Curve::EvalDN ( const double U,
    const int N ) const
    nodiscardpure virtual

    ◆ FirstParameter()

    virtual double Geom2d_Curve::FirstParameter ( ) const
    pure virtual

    ◆ IsClosed()

    virtual bool Geom2d_Curve::IsClosed ( ) const
    pure virtual

    Returns true if the curve is closed. Examples : Some curves such as circle are always closed, others such as line are never closed (by definition). Some Curves such as OffsetCurve can be closed or not. These curves are considered as closed if the distance between the first point and the last point of the curve is lower or equal to the Resolution from package gp which is a fixed criterion independent of the application.

    Implemented in Bisector_BisecAna, Bisector_BisecCC, Bisector_BisecPC, Geom2d_BezierCurve, Geom2d_BSplineCurve, Geom2d_Circle, Geom2d_Ellipse, Geom2d_Hyperbola, Geom2d_Line, Geom2d_OffsetCurve, Geom2d_Parabola, Geom2d_TrimmedCurve, Geom2dEval_AHTBezierCurve, Geom2dEval_ArchimedeanSpiralCurve, Geom2dEval_CircleInvoluteCurve, Geom2dEval_LogarithmicSpiralCurve, Geom2dEval_SineWaveCurve, and Geom2dEval_TBezierCurve.

    ◆ IsCN()

    virtual bool Geom2d_Curve::IsCN ( const int N) const
    pure virtual

    ◆ IsPeriodic()

    virtual bool Geom2d_Curve::IsPeriodic ( ) const
    pure virtual

    Returns true if the parameter of the curve is periodic. It is possible only if the curve is closed and if the following relation is satisfied : for each parametric value U the distance between the point P(u) and the point P (u + T) is lower or equal to Resolution from package gp, T is the period and must be a constant. There are three possibilities : . the curve is never periodic by definition (SegmentLine) . the curve is always periodic by definition (Circle) . the curve can be defined as periodic (BSpline). In this case a function SetPeriodic allows you to give the shape of the curve. The general rule for this case is : if a curve can be periodic or not the default periodicity set is non periodic and you have to turn (explicitly) the curve into a periodic curve if you want the curve to be periodic.

    Implemented in Bisector_BisecAna, Bisector_BisecCC, Bisector_BisecPC, Geom2d_BezierCurve, Geom2d_BSplineCurve, Geom2d_Circle, Geom2d_Ellipse, Geom2d_Hyperbola, Geom2d_Line, Geom2d_OffsetCurve, Geom2d_Parabola, Geom2d_TrimmedCurve, Geom2dEval_AHTBezierCurve, Geom2dEval_ArchimedeanSpiralCurve, Geom2dEval_CircleInvoluteCurve, Geom2dEval_LogarithmicSpiralCurve, Geom2dEval_SineWaveCurve, and Geom2dEval_TBezierCurve.

    ◆ LastParameter()

    ◆ ParametricTransformation()

    virtual double Geom2d_Curve::ParametricTransformation ( const gp_Trsf2d & T) const
    virtual

    Returns the coefficient required to compute the parametric transformation of this curve when transformation T is applied. This coefficient is the ratio between the parameter of a point on this curve and the parameter of the transformed point on the new curve transformed by T. Note: this function generally returns 1. but it can be redefined (for example, on a line).

    Reimplemented in Geom2d_Line, Geom2d_OffsetCurve, Geom2d_Parabola, and Geom2d_TrimmedCurve.

    ◆ Period()

    virtual double Geom2d_Curve::Period ( ) const
    virtual

    Returns the period of this curve. raises if the curve is not periodic.

    Reimplemented in Geom2d_OffsetCurve, and Geom2d_TrimmedCurve.

    ◆ Reverse()

    virtual void Geom2d_Curve::Reverse ( )
    pure virtual

    Changes the direction of parametrization of <me>. The "FirstParameter" and the "LastParameter" are not changed but the orientation of the curve is modified. If the curve is bounded the StartPoint of the initial curve becomes the EndPoint of the reversed curve and the EndPoint of the initial curve becomes the StartPoint of the reversed curve.

    Implemented in Bisector_BisecAna, Bisector_BisecCC, Bisector_BisecPC, Geom2d_BezierCurve, Geom2d_BSplineCurve, Geom2d_Conic, Geom2d_Line, Geom2d_OffsetCurve, Geom2d_TrimmedCurve, Geom2dEval_AHTBezierCurve, Geom2dEval_ArchimedeanSpiralCurve, Geom2dEval_CircleInvoluteCurve, Geom2dEval_LogarithmicSpiralCurve, Geom2dEval_SineWaveCurve, and Geom2dEval_TBezierCurve.

    ◆ Reversed()

    occ::handle< Geom2d_Curve > Geom2d_Curve::Reversed ( ) const
    nodiscard

    Creates a reversed duplicate Changes the orientation of this curve. The first and last parameters are not changed, but the parametric direction of the curve is reversed. If the curve is bounded:

    • the start point of the initial curve becomes the end point of the reversed curve, and
    • the end point of the initial curve becomes the start point of the reversed curve.
    • Reversed creates a new curve.

    ◆ ReversedParameter()

    virtual double Geom2d_Curve::ReversedParameter ( const double U) const
    pure virtual

    Computes the parameter on the reversed curve for the point of parameter U on this curve. Note: The point of parameter U on this curve is identical to the point of parameter ReversedParameter(U) on the reversed curve.

    Implemented in Bisector_BisecAna, Bisector_BisecCC, Bisector_BisecPC, Geom2d_BezierCurve, Geom2d_BSplineCurve, Geom2d_Circle, Geom2d_Conic, Geom2d_Ellipse, Geom2d_Hyperbola, Geom2d_Line, Geom2d_OffsetCurve, Geom2d_Parabola, Geom2d_TrimmedCurve, Geom2dEval_AHTBezierCurve, Geom2dEval_ArchimedeanSpiralCurve, Geom2dEval_CircleInvoluteCurve, Geom2dEval_LogarithmicSpiralCurve, Geom2dEval_SineWaveCurve, and Geom2dEval_TBezierCurve.

    ◆ TransformedParameter()

    virtual double Geom2d_Curve::TransformedParameter ( const double U,
    const gp_Trsf2d & T ) const
    virtual

    Computes the parameter on the curve transformed by T for the point of parameter U on this curve. Note: this function generally returns U but it can be redefined (for example, on a line).

    Reimplemented in Geom2d_Line, Geom2d_OffsetCurve, Geom2d_Parabola, and Geom2d_TrimmedCurve.

    ◆ Value()

    gp_Pnt2d Geom2d_Curve::Value ( const double U) const

    Computes the point of parameter U on <me>. Implemented with D0.


    The documentation for this class was generated from the following file: