Open CASCADE Technology
6.5.4
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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>
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 Standard_Real | ReversedParameter (const Standard_Real 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 Standard_Real | TransformedParameter (const Standard_Real 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 Standard_Real | 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). | |
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 Standard_Real | 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 Standard_Real | LastParameter () const =0 |
Value of the last parameter. Warnings : It can be RealFirst or RealLast from package Standard if the curve is infinite | |
virtual Standard_Boolean | 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 wich is a fixed criterion independant of the application. | |
virtual Standard_Boolean | 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 Standard_Real | Period () const |
Returns thne 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 Standard_Boolean | IsCN (const Standard_Integer 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 void | D0 (const Standard_Real U, gp_Pnt2d &P) const =0 |
Returns in P the point of parameter U. If the curve is periodic then the returned point is P(U) with U = Ustart + (U - Uend) where Ustart and Uend are the parametric bounds of the curve. Raised only for the "OffsetCurve" if it is not possible to compute the current point. For example when the first derivative on the basis curve and the offset direction are parallel. | |
virtual void | D1 (const Standard_Real U, gp_Pnt2d &P, gp_Vec2d &V1) const =0 |
Returns the point P of parameter U and the first derivative V1. //! Raised if the continuity of the curve is not C1. | |
virtual void | D2 (const Standard_Real U, gp_Pnt2d &P, gp_Vec2d &V1, gp_Vec2d &V2) const =0 |
Returns the point P of parameter U, the first and second derivatives V1 and V2. //! Raised if the continuity of the curve is not C2. | |
virtual void | D3 (const Standard_Real U, gp_Pnt2d &P, gp_Vec2d &V1, gp_Vec2d &V2, gp_Vec2d &V3) const =0 |
Returns the point P of parameter U, the first, the second and the third derivative. //! Raised if the continuity of the curve is not C3. | |
virtual gp_Vec2d | DN (const Standard_Real U, const Standard_Integer N) const =0 |
For the point of parameter U of this curve, computes the vector corresponding to the Nth derivative. Exceptions StdFail_UndefinedDerivative if: | |
gp_Pnt2d | Value (const Standard_Real U) const |
Computes the point of parameter U on <me>. If the curve is periodic then the returned point is P(U) with U = Ustart + (U - Uend) where Ustart and Uend are the parametric bounds of the curve. it is implemented with D0. Raised only for the "OffsetCurve" if it is not possible to compute the current point. For example when the first derivative on the basis curve and the offset direction are parallel. |
virtual GeomAbs_Shape Geom2d_Curve::Continuity | ( | ) | const [pure virtual] |
virtual void Geom2d_Curve::D0 | ( | const Standard_Real | U, |
gp_Pnt2d & | P | ||
) | const [pure virtual] |
virtual void Geom2d_Curve::D1 | ( | const Standard_Real | U, |
gp_Pnt2d & | P, | ||
gp_Vec2d & | V1 | ||
) | const [pure virtual] |
virtual void Geom2d_Curve::D2 | ( | const Standard_Real | U, |
gp_Pnt2d & | P, | ||
gp_Vec2d & | V1, | ||
gp_Vec2d & | V2 | ||
) | const [pure virtual] |
virtual void Geom2d_Curve::D3 | ( | const Standard_Real | U, |
gp_Pnt2d & | P, | ||
gp_Vec2d & | V1, | ||
gp_Vec2d & | V2, | ||
gp_Vec2d & | V3 | ||
) | const [pure virtual] |
virtual gp_Vec2d Geom2d_Curve::DN | ( | const Standard_Real | U, |
const Standard_Integer | N | ||
) | const [pure virtual] |
Implemented in Geom2d_BSplineCurve, Geom2d_Hyperbola, Geom2d_BezierCurve, Geom2d_Ellipse, Geom2d_TrimmedCurve, Geom2d_OffsetCurve, Geom2d_Parabola, Bisector_BisecCC, Bisector_BisecPC, Geom2d_Line, Geom2d_Circle, and Bisector_BisecAna.
virtual Standard_Real Geom2d_Curve::FirstParameter | ( | ) | const [pure virtual] |
virtual Standard_Boolean Geom2d_Curve::IsClosed | ( | ) | const [pure virtual] |
virtual Standard_Boolean Geom2d_Curve::IsCN | ( | const Standard_Integer | N | ) | const [pure virtual] |
virtual Standard_Boolean Geom2d_Curve::IsPeriodic | ( | ) | const [pure virtual] |
virtual Standard_Real Geom2d_Curve::LastParameter | ( | ) | const [pure virtual] |
virtual Standard_Real Geom2d_Curve::ParametricTransformation | ( | const gp_Trsf2d & | T | ) | const [virtual] |
Reimplemented in Geom2d_OffsetCurve, Geom2d_TrimmedCurve, Geom2d_Parabola, and Geom2d_Line.
virtual Standard_Real Geom2d_Curve::Period | ( | ) | const [virtual] |
Reimplemented in Geom2d_OffsetCurve, and Geom2d_TrimmedCurve.
virtual void Geom2d_Curve::Reverse | ( | ) | [pure virtual] |
Handle_Geom2d_Curve Geom2d_Curve::Reversed | ( | ) | const |
virtual Standard_Real Geom2d_Curve::ReversedParameter | ( | const Standard_Real | U | ) | const [pure virtual] |
virtual Standard_Real Geom2d_Curve::TransformedParameter | ( | const Standard_Real | U, |
const gp_Trsf2d & | T | ||
) | const [virtual] |
Reimplemented in Geom2d_OffsetCurve, Geom2d_TrimmedCurve, Geom2d_Parabola, and Geom2d_Line.
gp_Pnt2d Geom2d_Curve::Value | ( | const Standard_Real | U | ) | const |