// 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_Curve_HeaderFile #define _Geom_Curve_HeaderFile #include #include #include #include #include #include #include class gp_Trsf; class gp_Pnt; class gp_Vec; class Geom_Curve; DEFINE_STANDARD_HANDLE(Geom_Curve, Geom_Geometry) //! The abstract class Curve describes the common //! behavior of curves in 3D space. The Geom 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 Geom_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 states so explicitly. //! Warning //! The Geom package does not prevent the //! construction of curves with null length or curves which //! self-intersect. class Geom_Curve : public Geom_Geometry { public: //! Changes the direction of parametrization of . //! 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. Standard_EXPORT virtual void Reverse() = 0; //! Returns the parameter on the reversed curve for //! the point of parameter U on . //! //! me->Reversed()->Value(me->ReversedParameter(U)) //! //! is the same point as //! //! me->Value(U) Standard_EXPORT virtual Standard_Real ReversedParameter (const Standard_Real U) const = 0; //! Returns the parameter on the transformed curve for //! the transform of the point of parameter U on . //! //! me->Transformed(T)->Value(me->TransformedParameter(U,T)) //! //! is the same point as //! //! me->Value(U).Transformed(T) //! //! This methods returns //! //! It can be redefined. For example on the Line. Standard_EXPORT virtual Standard_Real TransformedParameter (const Standard_Real U, const gp_Trsf& T) const; //! Returns a coefficient to compute the parameter on //! the transformed curve for the transform of the //! point on . //! //! Transformed(T)->Value(U * ParametricTransformation(T)) //! //! is the same point as //! //! Value(U).Transformed(T) //! //! This methods returns 1. //! //! It can be redefined. For example on the Line. Standard_EXPORT virtual Standard_Real ParametricTransformation (const gp_Trsf& T) const; //! Returns a copy of reversed. Standard_NODISCARD Standard_EXPORT Handle(Geom_Curve) Reversed() const; //! Returns the value of the first parameter. //! Warnings : //! It can be RealFirst from package Standard //! if the curve is infinite Standard_EXPORT virtual Standard_Real FirstParameter() const = 0; //! Returns the value of the last parameter. //! Warnings : //! It can be RealLast from package Standard //! if the curve is infinite Standard_EXPORT virtual Standard_Real LastParameter() const = 0; //! Returns true if the curve is closed. //! 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. Standard_EXPORT virtual Standard_Boolean IsClosed() const = 0; //! Is the parametrization of the curve 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. Standard_EXPORT virtual Standard_Boolean IsPeriodic() const = 0; //! Returns the period of this curve. //! Exceptions Standard_NoSuchObject if this curve is not periodic. Standard_EXPORT virtual Standard_Real Period() const; //! 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. Standard_EXPORT virtual GeomAbs_Shape Continuity() 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. Standard_EXPORT virtual Standard_Boolean IsCN (const Standard_Integer N) 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. Standard_EXPORT virtual void D0 (const Standard_Real U, gp_Pnt& P) const = 0; //! Returns the point P of parameter U and the first derivative V1. //! Raised if the continuity of the curve is not C1. Standard_EXPORT virtual void D1 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1) 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. Standard_EXPORT virtual void D2 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1, gp_Vec& V2) 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. Standard_EXPORT virtual void D3 (const Standard_Real U, gp_Pnt& P, gp_Vec& V1, gp_Vec& V2, gp_Vec& V3) const = 0; //! The returned vector gives the value of the derivative for the //! order of derivation N. //! Raised if the continuity of the curve is not CN. //! //! Raised if the derivative cannot be computed //! easily. e.g. rational bspline and n > 3. //! Raised if N < 1. Standard_EXPORT virtual gp_Vec DN (const Standard_Real U, const Standard_Integer N) const = 0; //! Computes the point of parameter U on . //! 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. Standard_EXPORT gp_Pnt Value (const Standard_Real U) const; //! Dumps the content of me into the stream Standard_EXPORT virtual void DumpJson (Standard_OStream& theOStream, Standard_Integer theDepth = -1) const Standard_OVERRIDE; DEFINE_STANDARD_RTTIEXT(Geom_Curve,Geom_Geometry) protected: private: }; #endif // _Geom_Curve_HeaderFile