Geom_OffsetCurve Class Reference

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. More...

#include <Geom_OffsetCurve.hxx>

Inheritance diagram for Geom_OffsetCurve:

Public Member Functions
	Geom_OffsetCurve (const occ::handle< Geom_Curve > &C, const double Offset, const gp_Dir &V, const bool isNotCheckC0=false)
	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.
	Geom_OffsetCurve (const Geom_OffsetCurve &theOther)
	Copy constructor for optimized copying without validation.
bool	HasEvalRepresentation () const
	Returns true if an evaluation representation is attached.
const occ::handle< GeomEval_RepCurveDesc::Base > &	EvalRepresentation () const
	Returns the current evaluation representation descriptor (may be null).
void	SetEvalRepresentation (const occ::handle< GeomEval_RepCurveDesc::Base > &theDesc)
	Sets a new evaluation representation. Validates descriptor data and ensures no circular references.
void	ClearEvalRepresentation ()
	Removes the evaluation representation.
void	Reverse () final
	Changes the orientation of this offset curve. As a result:
double	ReversedParameter (const double U) const final
	Computes the parameter on the reversed curve for the point of parameter U on this offset curve.
void	SetBasisCurve (const occ::handle< Geom_Curve > &C, const bool isNotCheckC0=false)
	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.
void	SetDirection (const gp_Dir &V)
	Changes this offset curve by assigning V as the reference vector used to compute the offset direction.
void	SetOffsetValue (const double D)
	Changes this offset curve by assigning D as the offset value.
occ::handle< Geom_Curve >	BasisCurve () const
	Returns the basis curve of this offset curve. Note: The basis curve can be an offset curve.
GeomAbs_Shape	Continuity () const final
	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.
const gp_Dir &	Direction () const
	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.
gp_Pnt	EvalD0 (const double U) const final
	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.
Geom_Curve::ResD1	EvalD1 (const double U) const final
	Warning! this should not be called if the continuity of the basis curve is not C2. Nevertheless, it's OK to use it on a portion where the curve is C2.
Geom_Curve::ResD2	EvalD2 (const double U) const final
	Warning! this should not be called if the continuity of the basis curve is not C3. Nevertheless, it's OK to use it on a portion where the curve is C3.
Geom_Curve::ResD3	EvalD3 (const double U) const final
	Computes the point and first three derivatives at parameter U. Raises an exception if the curve continuity is not C3.
gp_Vec	EvalDN (const double U, const int N) const final
	The returned vector gives the value of the derivative for the order of derivation N.
double	FirstParameter () const final
	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.
double	LastParameter () const final
	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.
double	Offset () const
	Returns the offset value of this offset curve.
bool	IsClosed () const final
	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.
bool	IsCN (const int N) const final
	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.
bool	IsPeriodic () const final
	Returns true if this offset curve is periodic, i.e. if the basis curve of this offset curve is periodic.
double	Period () const final
	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.
void	Transform (const gp_Trsf &T) final
	Applies the transformation T to this offset curve. Note: the basis curve is also modified.
double	TransformedParameter (const double U, const gp_Trsf &T) const final
	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.
double	ParametricTransformation (const gp_Trsf &T) const final
	Returns a coefficient to compute the parameter on the transformed curve for the transform of the point on <me>.
occ::handle< Geom_Geometry >	Copy () const final
	Creates a new object which is a copy of this offset curve.
GeomAbs_Shape	GetBasisCurveContinuity () const
	Returns continuity of the basis curve.
void	DumpJson (Standard_OStream &theOStream, int theDepth=-1) const final
	Dumps the content of me into the stream.
Public Member Functions inherited from Geom_Curve
occ::handle< Geom_Curve >	Reversed () const
	Returns a copy of <me> reversed.
void	D0 (const double U, gp_Pnt &P) const
	Returns in P the point of parameter U.
void	D1 (const double U, gp_Pnt &P, gp_Vec &V1) const
	Returns the point P of parameter U and the first derivative V1.
void	D2 (const double U, gp_Pnt &P, gp_Vec &V1, gp_Vec &V2) const
	Returns the point P of parameter U, the first and second derivatives V1 and V2.
void	D3 (const double U, gp_Pnt &P, gp_Vec &V1, gp_Vec &V2, gp_Vec &V3) const
	Returns the point P of parameter U, the first, the second and the third derivative.
gp_Vec	DN (const double U, const int N) const
	The returned vector gives the value of the derivative for the order of derivation N.
gp_Pnt	Value (const double U) const
	Computes the point of parameter U on <me>.
Public Member Functions inherited from Geom_Geometry
void	Mirror (const gp_Pnt &P)
	Performs the symmetrical transformation of a Geometry with respect to the point P which is the center of the symmetry.
void	Mirror (const gp_Ax1 &A1)
	Performs the symmetrical transformation of a Geometry with respect to an axis placement which is the axis of the symmetry.
void	Mirror (const gp_Ax2 &A2)
	Performs the symmetrical transformation of a Geometry with respect to a plane. The axis placement A2 locates the plane of the symmetry : (Location, XDirection, YDirection).
void	Rotate (const gp_Ax1 &A1, const double Ang)
	Rotates a Geometry. A1 is the axis of the rotation. Ang is the angular value of the rotation in radians.
void	Scale (const gp_Pnt &P, const double S)
	Scales a Geometry. S is the scaling value.
void	Translate (const gp_Vec &V)
	Translates a Geometry. V is the vector of the translation.
void	Translate (const gp_Pnt &P1, const gp_Pnt &P2)
	Translates a Geometry from the point P1 to the point P2.
occ::handle< Geom_Geometry >	Mirrored (const gp_Pnt &P) const
occ::handle< Geom_Geometry >	Mirrored (const gp_Ax1 &A1) const
occ::handle< Geom_Geometry >	Mirrored (const gp_Ax2 &A2) const
occ::handle< Geom_Geometry >	Rotated (const gp_Ax1 &A1, const double Ang) const
occ::handle< Geom_Geometry >	Scaled (const gp_Pnt &P, const double S) const
occ::handle< Geom_Geometry >	Transformed (const gp_Trsf &T) const
occ::handle< Geom_Geometry >	Translated (const gp_Vec &V) const
occ::handle< Geom_Geometry >	Translated (const gp_Pnt &P1, const gp_Pnt &P2) const
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

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.

Constructor & Destructor Documentation

Geom_OffsetCurve() [1/2]

Geom_OffsetCurve::Geom_OffsetCurve	(	const occ::handle< Geom_Curve > &	C,
		const double	Offset,
		const gp_Dir &	V,
		const bool	isNotCheckC0 = false )

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.

Geom_OffsetCurve() [2/2]

Geom_OffsetCurve::Geom_OffsetCurve

(

const Geom_OffsetCurve &

theOther

)

Copy constructor for optimized copying without validation.

Parameters

[in]

theOther

the offset curve to copy from

Member Function Documentation

BasisCurve()

occ::handle< Geom_Curve > Geom_OffsetCurve::BasisCurve

(

)

const

Returns the basis curve of this offset curve. Note: The basis curve can be an offset curve.

ClearEvalRepresentation()

void Geom_OffsetCurve::ClearEvalRepresentation ( )

inline

Removes the evaluation representation.

Continuity()

GeomAbs_Shape Geom_OffsetCurve::Continuity ( ) const

finalvirtual

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.

Implements Geom_Curve.

Copy()

occ::handle< Geom_Geometry > Geom_OffsetCurve::Copy ( ) const

finalvirtual

Creates a new object which is a copy of this offset curve.

Implements Geom_Geometry.

Direction()

const gp_Dir & Geom_OffsetCurve::Direction

(

)

const

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.

DumpJson()

void Geom_OffsetCurve::DumpJson ( Standard_OStream & theOStream, int theDepth = -1 ) const

finalvirtual

Dumps the content of me into the stream.

Reimplemented from Geom_Curve.

EvalD0()

gp_Pnt Geom_OffsetCurve::EvalD0 ( const double U ) const

finalvirtual

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.

Implements Geom_Curve.

EvalD1()

Geom_Curve::ResD1 Geom_OffsetCurve::EvalD1 ( const double U ) const

finalvirtual

Warning! this should not be called if the continuity of the basis curve is not C2. Nevertheless, it's OK to use it on a portion where the curve is C2.

Implements Geom_Curve.

EvalD2()

Geom_Curve::ResD2 Geom_OffsetCurve::EvalD2 ( const double U ) const

finalvirtual

Warning! this should not be called if the continuity of the basis curve is not C3. Nevertheless, it's OK to use it on a portion where the curve is C3.

Implements Geom_Curve.

EvalD3()

Geom_Curve::ResD3 Geom_OffsetCurve::EvalD3 ( const double U ) const

finalvirtual

Computes the point and first three derivatives at parameter U. Raises an exception if the curve continuity is not C3.

Implements Geom_Curve.

EvalDN()

gp_Vec Geom_OffsetCurve::EvalDN ( const double U, const int N ) const

finalvirtual

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.

Implements Geom_Curve.

EvalRepresentation()

const occ::handle< GeomEval_RepCurveDesc::Base > & Geom_OffsetCurve::EvalRepresentation ( ) const

inline

Returns the current evaluation representation descriptor (may be null).

FirstParameter()

double Geom_OffsetCurve::FirstParameter ( ) const

finalvirtual

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.

Implements Geom_Curve.

GetBasisCurveContinuity()

GeomAbs_Shape Geom_OffsetCurve::GetBasisCurveContinuity

(

)

const

Returns continuity of the basis curve.

HasEvalRepresentation()

bool Geom_OffsetCurve::HasEvalRepresentation ( ) const

inline

Returns true if an evaluation representation is attached.

IsClosed()

bool Geom_OffsetCurve::IsClosed ( ) const

finalvirtual

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.

Implements Geom_Curve.

IsCN()

bool Geom_OffsetCurve::IsCN ( const int N ) const

finalvirtual

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.

Implements Geom_Curve.

IsPeriodic()

bool Geom_OffsetCurve::IsPeriodic ( ) const

finalvirtual

Returns true if this offset curve is periodic, i.e. if the basis curve of this offset curve is periodic.

Implements Geom_Curve.

LastParameter()

double Geom_OffsetCurve::LastParameter ( ) const

finalvirtual

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.

Implements Geom_Curve.

Offset()

double Geom_OffsetCurve::Offset

(

)

const

Returns the offset value of this offset curve.

ParametricTransformation()

double Geom_OffsetCurve::ParametricTransformation ( const gp_Trsf & T ) const

finalvirtual

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.

Reimplemented from Geom_Curve.

Period()

double Geom_OffsetCurve::Period ( ) const

finalvirtual

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.

Reimplemented from Geom_Curve.

Reverse()

void Geom_OffsetCurve::Reverse ( )

finalvirtual

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.

Implements Geom_Curve.

ReversedParameter()

double Geom_OffsetCurve::ReversedParameter ( const double U ) const

finalvirtual

Computes the parameter on the reversed curve for the point of parameter U on this offset curve.

Implements Geom_Curve.

SetBasisCurve()

void Geom_OffsetCurve::SetBasisCurve	(	const occ::handle< Geom_Curve > &	C,
		const bool	isNotCheckC0 = false )

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.

SetDirection()

void Geom_OffsetCurve::SetDirection

(

const gp_Dir &

V

)

Changes this offset curve by assigning V as the reference vector used to compute the offset direction.

SetEvalRepresentation()

void Geom_OffsetCurve::SetEvalRepresentation

(

const occ::handle< GeomEval_RepCurveDesc::Base > &

theDesc

)

Sets a new evaluation representation. Validates descriptor data and ensures no circular references.

SetOffsetValue()

void Geom_OffsetCurve::SetOffsetValue

(

const double

D

)

Changes this offset curve by assigning D as the offset value.

Transform()

void Geom_OffsetCurve::Transform ( const gp_Trsf & T )

finalvirtual

Applies the transformation T to this offset curve. Note: the basis curve is also modified.

Implements Geom_Geometry.

TransformedParameter()

double Geom_OffsetCurve::TransformedParameter ( const double U, const gp_Trsf & T ) const

finalvirtual

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.

Reimplemented from Geom_Curve.

---

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

• Geom_OffsetCurve.hxx