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The copying permission statements at the beginning of source files updated to refer to LGPL. Copyright dates extended till 2014 in advance.
264 lines
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264 lines
10 KiB
Plaintext
-- Created on: 1993-03-24
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-- Created by: JCV
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-- Copyright (c) 1993-1999 Matra Datavision
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-- Copyright (c) 1999-2014 OPEN CASCADE SAS
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--
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-- This file is part of Open CASCADE Technology software library.
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--
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-- This library is free software; you can redistribute it and / or modify it
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-- under the terms of the GNU Lesser General Public version 2.1 as published
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-- by the Free Software Foundation, with special exception defined in the file
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-- OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
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-- distribution for complete text of the license and disclaimer of any warranty.
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--
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-- Alternatively, this file may be used under the terms of Open CASCADE
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-- commercial license or contractual agreement.
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deferred class Curve from Geom2d inherits Geometry from Geom2d
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--- Purpose : The abstract class Curve describes the common
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-- behavior of curves in 2D space. The Geom2d
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-- package provides numerous concrete classes of
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-- derived curves, including lines, circles, conics, Bezier
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-- or BSpline curves, etc.
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-- The main characteristic of these curves is that they
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-- are parameterized. The Geom2d_Curve class shows:
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-- - how to work with the parametric equation of a
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-- curve in order to calculate the point of parameter
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-- u, together with the vector tangent and the
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-- derivative vectors of order 2, 3,..., N at this point;
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-- - how to obtain general information about the curve
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-- (for example, level of continuity, closed
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-- characteristics, periodicity, bounds of the parameter field);
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-- - how the parameter changes when a geometric
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-- transformation is applied to the curve or when the
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-- orientation of the curve is inverted.
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-- All curves must have a geometric continuity: a curve is
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-- at least "C0". Generally, this property is checked at
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-- the time of construction or when the curve is edited.
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-- Where this is not the case, the documentation
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-- explicitly states so.
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-- Warning
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-- The Geom2d package does not prevent the
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-- construction of curves with null length or curves which
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-- self-intersect.
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uses Pnt2d from gp,
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Vec2d from gp,
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Trsf2d from gp,
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Shape from GeomAbs
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raises RangeError from Standard,
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NoSuchObject from Standard,
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UndefinedDerivative from Geom2d,
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UndefinedValue from Geom2d
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is
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Reverse (me : mutable)
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--- Purpose :
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-- Changes the direction of parametrization of <me>.
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-- The "FirstParameter" and the "LastParameter" are not changed
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-- but the orientation of the curve is modified. If the curve
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-- is bounded the StartPoint of the initial curve becomes the
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-- EndPoint of the reversed curve and the EndPoint of the initial
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-- curve becomes the StartPoint of the reversed curve.
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is deferred;
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ReversedParameter(me; U : Real) returns Real
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---Purpose: Computes the parameter on the reversed curve for
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-- the point of parameter U on this curve.
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-- Note: The point of parameter U on this curve is
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-- identical to the point of parameter
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-- ReversedParameter(U) on the reversed curve.
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is deferred;
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TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real
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---Purpose: Computes the parameter on the curve transformed by
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-- T for the point of parameter U on this curve.
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-- Note: this function generally returns U but it can be
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-- redefined (for example, on a line).
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is virtual;
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ParametricTransformation(me; T : Trsf2d from gp) returns Real
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---Purpose: Returns the coefficient required to compute the
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-- parametric transformation of this curve when
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-- transformation T is applied. This coefficient is the
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-- ratio between the parameter of a point on this curve
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-- and the parameter of the transformed point on the
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-- new curve transformed by T.
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-- Note: this function generally returns 1. but it can be
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-- redefined (for example, on a line).
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is virtual;
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Reversed (me) returns mutable like me
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--- Purpose : Creates a reversed duplicate Changes the orientation of this curve. The first and
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-- last parameters are not changed, but the parametric
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-- direction of the curve is reversed.
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-- If the curve is bounded:
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-- - the start point of the initial curve becomes the end
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-- point of the reversed curve, and
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-- - the end point of the initial curve becomes the start
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-- point of the reversed curve.
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-- - Reversed creates a new curve.
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is static;
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FirstParameter (me) returns Real
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--- Purpose : Returns the value of the first parameter.
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-- Warnings :
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-- It can be RealFirst or RealLast from package Standard
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-- if the curve is infinite
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is deferred;
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LastParameter (me) returns Real
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--- Purpose : Value of the last parameter.
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-- Warnings :
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-- It can be RealFirst or RealLast from package Standard
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-- if the curve is infinite
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is deferred;
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IsClosed (me) returns Boolean
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--- Purpose : Returns true if the curve is closed.
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-- Examples :
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-- Some curves such as circle are always closed, others such as line
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-- are never closed (by definition).
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-- Some Curves such as OffsetCurve can be closed or not. These curves
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-- are considered as closed if the distance between the first point
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-- and the last point of the curve is lower or equal to the Resolution
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-- from package gp wich is a fixed criterion independant of the
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-- application.
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is deferred;
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IsPeriodic (me) returns Boolean
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--- Purpose :
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-- Returns true if the parameter of the curve is periodic.
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-- It is possible only if the curve is closed and if the
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-- following relation is satisfied :
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-- for each parametric value U the distance between the point
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-- P(u) and the point P (u + T) is lower or equal to Resolution
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-- from package gp, T is the period and must be a constant.
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-- There are three possibilities :
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-- . the curve is never periodic by definition (SegmentLine)
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-- . the curve is always periodic by definition (Circle)
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-- . the curve can be defined as periodic (BSpline). In this case
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-- a function SetPeriodic allows you to give the shape of the
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-- curve. The general rule for this case is : if a curve can be
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-- periodic or not the default periodicity set is non periodic
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-- and you have to turn (explicitly) the curve into a periodic
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-- curve if you want the curve to be periodic.
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is deferred;
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Period (me) returns Real from Standard
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---Purpose: Returns thne period of this curve.
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raises
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NoSuchObject from Standard
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---Purpose: raises if the curve is not periodic
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is virtual;
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Continuity (me) returns Shape from GeomAbs
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--- Purpose :
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-- It is the global continuity of the curve :
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-- C0 : only geometric continuity,
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-- C1 : continuity of the first derivative all along the Curve,
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-- C2 : continuity of the second derivative all along the Curve,
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-- C3 : continuity of the third derivative all along the Curve,
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-- G1 : tangency continuity all along the Curve,
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-- G2 : curvature continuity all along the Curve,
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-- CN : the order of continuity is infinite.
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is deferred;
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IsCN (me; N : Integer) returns Boolean
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--- Purpose : Returns true if the degree of continuity of this curve is at least N.
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-- Exceptions Standard_RangeError if N is less than 0.
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raises RangeError
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is deferred;
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D0(me; U : Real; P : out Pnt2d)
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---Purpose: Returns in P the point of parameter U.
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-- If the curve is periodic then the returned point is P(U) with
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-- U = Ustart + (U - Uend) where Ustart and Uend are the
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-- parametric bounds of the curve.
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raises UndefinedValue
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---Purpose :
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-- Raised only for the "OffsetCurve" if it is not possible to
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-- compute the current point. For example when the first
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-- derivative on the basis curve and the offset direction
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-- are parallel.
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is deferred;
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D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d)
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--- Purpose :
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-- Returns the point P of parameter U and the first derivative V1.
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raises UndefinedDerivative
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--- Purpose : Raised if the continuity of the curve is not C1.
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is deferred;
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D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d)
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--- Purpose :
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-- Returns the point P of parameter U, the first and second
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-- derivatives V1 and V2.
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raises UndefinedDerivative
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--- Purpose : Raised if the continuity of the curve is not C2.
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is deferred;
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D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d)
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--- Purpose :
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-- Returns the point P of parameter U, the first, the second
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-- and the third derivative.
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raises UndefinedDerivative
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--- Purpose : Raised if the continuity of the curve is not C3.
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is deferred;
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DN (me; U : Real; N : Integer) returns Vec2d
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--- Purpose : For the point of parameter U of this curve, computes
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-- the vector corresponding to the Nth derivative.
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-- Exceptions
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-- StdFail_UndefinedDerivative if:
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-- - the continuity of the curve is not "CN", or
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-- - the derivative vector cannot be computed easily;
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-- this is the case with specific types of curve (for
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-- example, a rational BSpline curve where N is greater than 3).
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-- Standard_RangeError if N is less than 1.
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raises UndefinedDerivative,
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RangeError
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is deferred;
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Value (me; U : Real) returns Pnt2d
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--- Purpose : Computes the point of parameter U on <me>.
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-- If the curve is periodic then the returned point is P(U) with
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-- U = Ustart + (U - Uend) where Ustart and Uend are the
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-- parametric bounds of the curve.
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--
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-- it is implemented with D0.
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raises UndefinedValue
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--- Purpose :
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-- Raised only for the "OffsetCurve" if it is not possible to
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-- compute the current point. For example when the first
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-- derivative on the basis curve and the offset direction
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-- are parallel.
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is static;
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end;
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