[occt.git] / src / Geom2d / Geom2d_OffsetCurve.cdl

-- Created on: 1993-03-24
-- Created by: Philippe DAUTRY
-- 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.

class OffsetCurve from Geom2d inherits Curve from Geom2d

 
        --- Purpose :  
        --  This class implements the basis services for the creation,
        --  edition, modification and evaluation of planar offset curve.
        --  The offset curve is obtained by offsetting by distance along 
        --  the normal to a basis curve defined in 2D 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 and the offset curve takes its parametrization from
        --  the basis curve. The Offset curve is in the direction of the
        --  normal to the basis curve N.
        --  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 ^ Z)) / ||T ^ Z||
        --  where T is the tangent vector to the basis curve and Z the 
        --  direction of the normal vector to the plane of the curve,
        --  N = T ^ Z defines the offset direction and should not have 
        --  null length. 
        --  
        --  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^Z|| != 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. 

uses Dir2d    from gp,
     Pnt2d    from gp,
     Trsf2d   from gp,
     Vec2d    from gp,
     Curve    from Geom2d,
     Geometry from Geom2d,
     Shape    from GeomAbs


raises ConstructionError   from Standard,
       RangeError          from Standard,
       NoSuchObject        from Standard,
       UndefinedDerivative from Geom2d,
       UndefinedValue      from Geom2d,
       NotImplemented      from Standard


is


  Create (C : Curve from Geom2d;
          Offset : Real;
          isNotCheckC0 : Boolean = Standard_False)

  returns OffsetCurve
        --- Purpose : Constructs a curve offset from the basis curve C,
    	-- where Offset is the distance between the offset
    	-- curve and the basis curve at any point.
    	-- A point on the offset curve is built by measuring the
    	-- offset value along a normal vector at a point on C.
    	-- This normal vector is obtained by rotating the
    	-- vector tangential to C at 90 degrees in the
    	-- anti-trigonometric sense. The side of C on which
    	-- the offset value is measured is indicated by this
    	-- normal vector if Offset is positive, or in the inverse
    	-- sense if Offset is negative.
      -- 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 
	--  Warning!  if isNotCheckC0 = false, 
	    -- ConstructionError  raised if the basis curve C is not at least C1.
        --  No check is done to know if ||V^Z|| != 0.0 at any point.
     raises ConstructionError;

        
  Reverse (me : mutable);
        --- Purpose : Changes the direction of parametrization of <me>.
    	--     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.


  ReversedParameter(me; U : Real) returns Real;
    	---Purpose: Computes the parameter on the reversed curve for
    	-- the point of parameter U on this offset curve.


  SetBasisCurve ( me : mutable;
                  C : Curve from Geom2d;
                  isNotCheckC0 : Boolean = Standard_False)
     raises ConstructionError;
        --- Purpose : 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
		-- if isNotCheckC0 = false, 
    	-- Standard_ConstructionError if the curve C is not at least "C1" continuous.

  SetOffsetValue (me : mutable; D : Real);
        --- Purpose :  Changes this offset curve by assigning D as the offset value.
        
  BasisCurve (me) returns Curve from Geom2d;
        --- Purpose : Returns the basis curve of this offset curve. The basis curve can be an offset curve.
    	

  Continuity (me)  returns Shape from GeomAbs;
        --- Purpose :
        --  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 normal direction defined
        --  at any point.


        --- Purpose  : 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
        --  Z the direction normal to the plane of the curve, the
        --  relation ||T(U) ^ Z|| != 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.


  D0 (me; U : Real; P : out Pnt2d)
     raises UndefinedValue;
 	---Purpose:  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
 

  D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d)
     raises UndefinedDerivative;
        ---Purpose:  Warning! this should not be called 
        --           if the continuity of the basis curve is not C2.
        --           Nevertheless, it's OK to use it  on portion 
        --           where the curve is C2


  D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d)
     raises UndefinedDerivative;
        ---Purpose:  Warning!  This  should  not  be called 
        --           if the continuity of the basis curve is not C3.
        --           Nevertheless, it's OK to use it  on portion 
        --           where the curve is C3  

  D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d)
     raises UndefinedDerivative;

     	---Purpose:  Warning! This should not be called 
        --           if the continuity of the basis curve is not C4.
        --           Nevertheless, it's OK to use it  on portion 
        --           where the curve is C4          

  DN (me; U : Real; N : Integer)   returns Vec2d
        --- Purpose : The returned vector gives the value of the derivative
        --  for the order of derivation N.      
    	--  Warning! this should not be called 
    	--        raises  UndefunedDerivative   if the continuity of the basis curve is not CN+1.
        --           Nevertheless, it's OK to use it  on portion 
        --           where the curve is CN+1  
    	-- raises  RangeError if N < 1. 
   	-- raises  NotImplemented if N > 3. 
    
     raises UndefinedDerivative,

            RangeError,
            NotImplemented; 


        --- Purpose : 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
        --  Warnings :
        --  The exception UndefinedValue or UndefinedDerivative is 
        --  raised if it is not possible to compute a unique offset direction.


  Value (me; U : Real; P, Pbasis : out Pnt2d; V1basis : out Vec2d)
     raises UndefinedValue;

    	---Purpose:  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 
  

  D1 (me; U : Real; P, Pbasis : out Pnt2d;
      V1, V1basis, V2basis : out Vec2d)
     raises UndefinedDerivative;

        ---Purpose:  Warning! this should not be called 
        --           if the continuity of the basis curve is not C1.
        --           Nevertheless, it's OK to use it  on portion 
        --           where the curve is C1

  D2 (me; U : Real; P, Pbasis : out Pnt2d;  V1, V2, V1basis, V2basis, 
      V3basis : out Vec2d)
     raises UndefinedDerivative;

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

  FirstParameter (me)  returns Real;

  LastParameter (me)   returns Real;
    	---Purpose: Returns the value of the first or last parameter of this
    	-- offset curve. The first parameter corresponds to the
    	-- start point of the 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.
        
  Offset (me)          returns Real;
    	---Purpose: Returns the offset value of this offset curve.

  IsClosed (me)   returns Boolean;
        --- Purpose :
        --  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.


  IsCN (me; N : Integer)  returns Boolean
        --- Purpose : Is the order of continuity of the curve N ?
        --   Warnings :
        --  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.
     raises RangeError;
        --- Purpose : Raised if N < 0.


  IsPeriodic (me)  returns Boolean;
        --- Purpose : Is the parametrization of a curve is periodic ?
        --  If the basis curve is a circle or an ellipse the corresponding
        --  OffsetCurve is periodic. If the basis curve can't be periodic 
        --  (for example BezierCurve) the OffsetCurve can't be periodic.


  Period (me) returns Real from Standard
    	---Purpose: 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.
  raises  NoSuchObject from Standard
  is redefined;


  Transform (me : mutable; T : Trsf2d);
        ---Purpose : Applies the transformation T to this offset curve.
    	-- Note: the basis curve is also modified.

  TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real
	---Purpose: 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.
     is redefined;  

  ParametricTransformation(me; T : Trsf2d from gp) returns Real
	---Purpose: 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.
     is redefined;  


  Copy (me)  returns like me;
    	---Purpose: Creates a new object, which is a copy of this offset curve.   

  GetBasisCurveContinuity(me)
    returns Shape from GeomAbs;
    	---Purpose: Returns continuity of the basis curve.   
    
      
fields

  basisCurve  : Curve from Geom2d;
  offsetValue : Real;
  myBasisCurveContinuity : Shape from GeomAbs;

end;
Commit	Line	Data
b311480e	1	-- Created on: 1993-03-24
	2	-- Created by: Philippe DAUTRY
	3	-- Copyright (c) 1993-1999 Matra Datavision
973c2be1	4	-- Copyright (c) 1999-2014 OPEN CASCADE SAS
b311480e	5	--
973c2be1	6	-- This file is part of Open CASCADE Technology software library.
b311480e	7	--
d5f74e42	8	-- This library is free software; you can redistribute it and/or modify it under
d5f74e42	9	-- the terms of the GNU Lesser General Public License version 2.1 as published
973c2be1	10	-- by the Free Software Foundation, with special exception defined in the file
	11	-- OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
	12	-- distribution for complete text of the license and disclaimer of any warranty.
b311480e	13	--
973c2be1	14	-- Alternatively, this file may be used under the terms of Open CASCADE
973c2be1	15	-- commercial license or contractual agreement.
7fd59977	16
	17	class OffsetCurve from Geom2d inherits Curve from Geom2d
	18
	19
	20	--- Purpose :
	21	-- This class implements the basis services for the creation,
	22	-- edition, modification and evaluation of planar offset curve.
	23	-- The offset curve is obtained by offsetting by distance along
	24	-- the normal to a basis curve defined in 2D space.
	25	-- The offset curve in this package can be a self intersecting
	26	-- curve even if the basis curve does not self-intersect.
	27	-- The self intersecting portions are not deleted at the
	28	-- construction time.
	29	-- An offset curve is a curve at constant distance (Offset) from a
	30	-- basis curve and the offset curve takes its parametrization from
	31	-- the basis curve. The Offset curve is in the direction of the
	32	-- normal to the basis curve N.
	33	-- The distance offset may be positive or negative to indicate the
	34	-- preferred side of the curve :
	35	-- . distance offset >0 => the curve is in the direction of N
	36	-- . distance offset >0 => the curve is in the direction of - N
	37	-- On the Offset curve :
	38	-- Value(u) = BasisCurve.Value(U) + (Offset * (T ^ Z)) / \|\|T ^ Z\|\|
	39	-- where T is the tangent vector to the basis curve and Z the
	40	-- direction of the normal vector to the plane of the curve,
	41	-- N = T ^ Z defines the offset direction and should not have
	42	-- null length.
	43	--
	44	-- Warnings :
	45	-- In this package we suppose that the continuity of the offset
	46	-- curve is one degree less than the continuity of the
	47	-- basis curve and we don't check that at any point \|\|T^Z\|\| != 0.0
	48	--
	49	-- So to evaluate the curve it is better to check that the offset
	50	-- curve is well defined at any point because an exception could
	51	-- be raised. The check is not done in this package at the creation
	52	-- of the offset curve because the control needs the use of an
	53	-- algorithm which cannot be implemented in this package.
	54	-- The OffsetCurve is closed if the first point and the last point
	55	-- are the same (The distance between these two points is lower or
	56	-- equal to the Resolution sea package gp) . The OffsetCurve can be
	57	-- closed even if the basis curve is not closed.
	58
	59	uses Dir2d from gp,
	60	Pnt2d from gp,
	61	Trsf2d from gp,
	62	Vec2d from gp,
	63	Curve from Geom2d,
	64	Geometry from Geom2d,
	65	Shape from GeomAbs
	66
	67
	68	raises ConstructionError from Standard,
	69	RangeError from Standard,
	70	NoSuchObject from Standard,
	71	UndefinedDerivative from Geom2d,
	72	UndefinedValue from Geom2d,
	73	NotImplemented from Standard
	74
	75
	76
	77	is
	78
	79
3d58dc49	80	Create (C : Curve from Geom2d;
	81	Offset : Real;
	82	isNotCheckC0 : Boolean = Standard_False)
	83
	84	returns OffsetCurve
7fd59977	85	--- Purpose : Constructs a curve offset from the basis curve C,
	86	-- where Offset is the distance between the offset
	87	-- curve and the basis curve at any point.
	88	-- A point on the offset curve is built by measuring the
	89	-- offset value along a normal vector at a point on C.
	90	-- This normal vector is obtained by rotating the
	91	-- vector tangential to C at 90 degrees in the
	92	-- anti-trigonometric sense. The side of C on which
	93	-- the offset value is measured is indicated by this
	94	-- normal vector if Offset is positive, or in the inverse
	95	-- sense if Offset is negative.
3d58dc49	96	-- If isNotCheckC0 = TRUE checking if basis curve has C0-continuity
3d58dc49	97	-- is not made.
7fd59977	98	-- Warnings :
	99	-- In this package the entities are not shared. The OffsetCurve is
	100	-- built with a copy of the curve C. So when C is modified the
	101	-- OffsetCurve is not modified
3d58dc49	102	-- Warning! if isNotCheckC0 = false,
3d58dc49	103	-- ConstructionError raised if the basis curve C is not at least C1.
7fd59977	104	-- No check is done to know if \|\|V^Z\|\| != 0.0 at any point.
	105	raises ConstructionError;
	106
	107
	108
	109	Reverse (me : mutable);
	110	--- Purpose : Changes the direction of parametrization of <me>.
	111	-- As a result:
	112	-- - the basis curve is reversed,
	113	-- - the start point of the initial curve becomes the end
	114	-- point of the reversed curve,
	115	-- - the end point of the initial curve becomes the start
	116	-- point of the reversed curve, and
	117	-- - the first and last parameters are recomputed.
	118
	119
	120	ReversedParameter(me; U : Real) returns Real;
	121	---Purpose: Computes the parameter on the reversed curve for
	122	-- the point of parameter U on this offset curve.
	123
	124
3d58dc49	125	SetBasisCurve ( me : mutable;
	126	C : Curve from Geom2d;
	127	isNotCheckC0 : Boolean = Standard_False)
7fd59977	128	raises ConstructionError;
	129	--- Purpose : Changes this offset curve by assigning C as the
	130	-- basis curve from which it is built.
3d58dc49	131	-- If isNotCheckC0 = TRUE checking if basis curve has C0-continuity
3d58dc49	132	-- is not made.
7fd59977	133	-- Exceptions
3d58dc49	134	-- if isNotCheckC0 = false,
7fd59977	135	-- Standard_ConstructionError if the curve C is not at least "C1" continuous.
	136
	137	SetOffsetValue (me : mutable; D : Real);
	138	--- Purpose : Changes this offset curve by assigning D as the offset value.
	139
	140	BasisCurve (me) returns Curve from Geom2d;
	141	--- Purpose : Returns the basis curve of this offset curve. The basis curve can be an offset curve.
	142
	143
	144
	145	Continuity (me) returns Shape from GeomAbs;
	146	--- Purpose :
	147	-- Continuity of the Offset curve :
	148	-- C0 : only geometric continuity,
	149	-- C1 : continuity of the first derivative all along the Curve,
	150	-- C2 : continuity of the second derivative all along the Curve,
	151	-- C3 : continuity of the third derivative all along the Curve,
	152	-- G1 : tangency continuity all along the Curve,
	153	-- G2 : curvature continuity all along the Curve,
	154	-- CN : the order of continuity is infinite.
	155	-- Warnings :
	156	-- Returns the continuity of the basis curve - 1.
	157	-- The offset curve must have a unique normal direction defined
	158	-- at any point.
	159
	160
	161
	162
	163
	164	--- Purpose : Value and derivatives
	165	--
	166	-- Warnings :
	167	-- The exception UndefinedValue or UndefinedDerivative is
	168	-- raised if it is not possible to compute a unique offset
	169	-- direction.
	170	-- If T is the first derivative with not null length and
	171	-- Z the direction normal to the plane of the curve, the
	172	-- relation \|\|T(U) ^ Z\|\| != 0 must be satisfied to evaluate
	173	-- the offset curve.
	174	-- No check is done at the creation time and we suppose
	175	-- in this package that the offset curve is well defined.
	176
	177
	178	D0 (me; U : Real; P : out Pnt2d)
	179	raises UndefinedValue;
	180	---Purpose: Warning! this should not be called
	181	-- if the basis curve is not at least C1. Nevertheless
	182	-- if used on portion where the curve is C1, it is OK
	183
	184
	185
	186	D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d)
	187	raises UndefinedDerivative;
	188	---Purpose: Warning! this should not be called
	189	-- if the continuity of the basis curve is not C2.
	190	-- Nevertheless, it's OK to use it on portion
	191	-- where the curve is C2
	192
	193
	194
	195	D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d)
	196	raises UndefinedDerivative;
	197	---Purpose: Warning! This should not be called
	198	-- if the continuity of the basis curve is not C3.
199	-- Nevertheless, it's OK to use it on portion
200	-- where the curve is C3
201
202	D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d)
203	raises UndefinedDerivative;
204
205	---Purpose: Warning! This should not be called
206	-- if the continuity of the basis curve is not C4.
207	-- Nevertheless, it's OK to use it on portion
208	-- where the curve is C4
209
210	DN (me; U : Real; N : Integer) returns Vec2d
211	--- Purpose : The returned vector gives the value of the derivative
212	-- for the order of derivation N.
213	-- Warning! this should not be called
214	-- raises UndefunedDerivative if the continuity of the basis curve is not CN+1.
215	-- Nevertheless, it's OK to use it on portion
216	-- where the curve is CN+1
217	-- raises RangeError if N < 1.
218	-- raises NotImplemented if N > 3.
219
220	raises UndefinedDerivative,
221
222	RangeError,
223	NotImplemented;
224
225
226
227	--- Purpose : The following functions compute the value and derivatives
228	-- on the offset curve and returns the derivatives on the
229	-- basis curve too.
230	-- The computation of the value and derivatives on the basis
231	-- curve are used to evaluate the offset curve
232	-- Warnings :
233	-- The exception UndefinedValue or UndefinedDerivative is
234	-- raised if it is not possible to compute a unique offset direction.
235
236
237	Value (me; U : Real; P, Pbasis : out Pnt2d; V1basis : out Vec2d)
238	raises UndefinedValue;
239
240	---Purpose: Warning! this should not be called
241	-- if the basis curve is not at least C1. Nevertheless
242	-- if used on portion where the curve is C1, it is OK
243
244
245	D1 (me; U : Real; P, Pbasis : out Pnt2d;
246	V1, V1basis, V2basis : out Vec2d)
247	raises UndefinedDerivative;
248
249	---Purpose: Warning! this should not be called
250	-- if the continuity of the basis curve is not C1.
251	-- Nevertheless, it's OK to use it on portion
252	-- where the curve is C1
253
254	D2 (me; U : Real; P, Pbasis : out Pnt2d; V1, V2, V1basis, V2basis,
255	V3basis : out Vec2d)
256	raises UndefinedDerivative;
257
258	---Purpose: Warning! this should not be called
259	-- if the continuity of the basis curve is not C3.
260	-- Nevertheless, it's OK to use it on portion
261	-- where the curve is C3
262
263	FirstParameter (me) returns Real;
264
265	LastParameter (me) returns Real;
266	---Purpose: Returns the value of the first or last parameter of this
267	-- offset curve. The first parameter corresponds to the
268	-- start point of the curve. The last parameter
269	-- corresponds to the end point.
270	-- Note: the first and last parameters of this offset curve
271	-- are also the ones of its basis curve.
272
273	Offset (me) returns Real;
274	---Purpose: Returns the offset value of this offset curve.
275
276	IsClosed (me) returns Boolean;
277	--- Purpose :
278	-- Returns True if the distance between the start point
279	-- and the end point of the curve is lower or equal to
280	-- Resolution from package gp.
281
282
283	IsCN (me; N : Integer) returns Boolean
284	--- Purpose : Is the order of continuity of the curve N ?
285	-- Warnings :
286	-- This method answer True if the continuity of the basis curve
287	-- is N + 1. We suppose in this class that a normal direction
288	-- to the basis curve (used to compute the offset curve) is
289	-- defined at any point on the basis curve.
290	raises RangeError;
291	--- Purpose : Raised if N < 0.
292
293
294	IsPeriodic (me) returns Boolean;
295	--- Purpose : Is the parametrization of a curve is periodic ?
296	-- If the basis curve is a circle or an ellipse the corresponding
297	-- OffsetCurve is periodic. If the basis curve can't be periodic
298	-- (for example BezierCurve) the OffsetCurve can't be periodic.
299
300
301	Period (me) returns Real from Standard
302	---Purpose: Returns the period of this offset curve, i.e. the period
303	-- of the basis curve of this offset curve.
304	-- Exceptions
305	-- Standard_NoSuchObject if the basis curve is not periodic.
306	raises NoSuchObject from Standard
307	is redefined;
308
309
310	Transform (me : mutable; T : Trsf2d);
311	---Purpose : Applies the transformation T to this offset curve.
312	-- Note: the basis curve is also modified.
313
314	TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real
315	---Purpose: Returns the parameter on the transformed curve for
316	-- the transform of the point of parameter U on <me>.
317	--
318	-- me->Transformed(T)->Value(me->TransformedParameter(U,T))
319	--
320	-- is the same point as
321	--
322	-- me->Value(U).Transformed(T)
323	--
324	-- This methods calls the basis curve method.
325	is redefined;
326
327	ParametricTransformation(me; T : Trsf2d from gp) returns Real
328	---Purpose: Returns a coefficient to compute the parameter on
329	-- the transformed curve for the transform of the
330	-- point on <me>.
331	--
332	-- Transformed(T)->Value(U * ParametricTransformation(T))
333	--
334	-- is the same point as
335	--
336	-- Value(U).Transformed(T)
337	--
338	-- This methods calls the basis curve method.
339	is redefined;
340
341
342
6e33d3ce	343	Copy (me) returns like me;
3d58dc49	344	---Purpose: Creates a new object, which is a copy of this offset curve.
	345
	346	GetBasisCurveContinuity(me)
	347	returns Shape from GeomAbs;
	348	---Purpose: Returns continuity of the basis curve.
	349
	350
7fd59977	351	fields
	352
	353	basisCurve : Curve from Geom2d;
	354	offsetValue : Real;
3d58dc49	355	myBasisCurveContinuity : Shape from GeomAbs;
7fd59977	356
7fd59977	357	end;