-- Created on: 1992-10-08
-- Created by: Isabelle GRIGNON
-- Copyright (c) 1992-1999 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.

package Adaptor2d 

	---Purpose: The  Adaptor2d package   is  used to  help  defining
	--          reusable  geometric  algorithms. i.e.  that can be
	--          used on curves and surfaces.
	--          
	--          It defines general services for  objects :
	--          
	--          - the 2d curve.     Curve2d
	--          
	--          The services are :
	--          
	--           - Usual services found in Geom or Geom2d :
	--           
	--               * parameter range, value and derivatives, etc...
	--               
	--           - Continuity breakout services :
	--           
	--               * Allows to  divide a curve or  a surfaces in
	--               parts with a given derivation order.
	--               
	--           - Special geometries detection services :
	--           
	--               * Allows to  test  for special cases that can
	--               be processed more easily :
	--                 - Conics, Quadrics, Bezier, BSpline ...
	--                 
	--                 And to  get the correponding  data form the
	--                 package  gp  or   Geom.   The  special type
	--                 OtherCurve  means  that no special case has
	--                 been  detected  and the  algorithm  may use
	--                 only the evaluation methods (D0, D1, ...)
	--                 
	--            
	--          For   each category  Curve2d,  Curve,   Surface we
	--          define   three  classes,  we  illustrate  now  the
	--          principles  with the  Curve,  the same  applies to
	--          Curve2d and Surface.
	--          
	--          The  class Curve  is the   abstract root  for  all
	--          Curves used by algorithms,  it is handled by value
	--          and   provides as  deferred  methods  the services
	--          described above.
	--          
	--          Some  services  (breakout) requires  to create new
	--          curves,     this   leads   to   memory  allocation
	--          considerations (who create  the curve, who deletes
	--          it ?). To  solve this problem elegantly the  curve
	--          will  return a  HCurve, the    HCurve is a   curve
	--          handled by reference   so it will   be deallocated
	--          automatically when it is not used.
	--          
	--          A third class GenHCurve is provided, this class is
	--          generic and its utility   is to provide  automatic
	--          generation  of  the  HCurve  class  when you  have
	--          written the Curve class.
	--          
	--             
	--          * Let us show an example (with 2d curves) :
	--          
	--            Imagine an  algorithm to intersect  curves, this
	--            algorithms  is written to  process  Curve2d from
	--            Adaptor2d :
	--            
	--            A method may look like :
	--            
	--            Intersect(C1,C2 : Curve2d from Adaptor2d);
	--            
	--            Which will look like in C++
	--            
	--            Intersect(const Adaptor2d_Curve2d& C1,
	--                      const Adaptor2d_Curve2d& C2)
	--            {
	--             // you can call any method
	--             Standard_Real first1 = C1.FirstParameter();
	--             
	--             // but avoid  to copy in an Adaptor2d_Curve which
	--             // is an Abstract class, use a reference or a pointer
	--            
	--             const Adaptor2d_Curve& C  = C1;
	--             const Adaptor2d_Curve *pC = &C1;
	--             
	--             // If you  are interseted in Intervals you must
	--             // store them in a  HCurve to ensure they are kept
	--             // in memory. Then a referrence may be used.
	--             
	--             Handle(Adaptor2d_HCurve) HCI = C1.Interval(1);
	--             
	--             const Adaptor2d_Curve& CI = HCI->Curve();
	--             pC = &(HCI->Curve());
	--            
	--            
	--          *  The   Adaptor2d  provides  also  Generic  classes
	--          implementing algorithmic curves and surfaces.
	--          
	--              - IsoCurve       : Isoparametric curve on a surface.
	--              - CurveOnSurface :  2D curve in the parametric
	--              space of a surface.
	--              
	--              
	--              - OffsetCurve2d : 2d offset curve
	--              - ProjectedCurve : 3d curve projected on a plane
	--              - SurfaceOfLinearExtrusion 
	--              - SurfaceOfRevolution
	--              
	--              They are instantiated with HCurve, HSurface, HCurved2d

uses 
    Standard,
    MMgt,
    TColStd,
    GeomAbs,
    TColgp,
    gp,
    Geom2d,
    math

is

      deferred class Curve2d; 
       ---Purpose: Root of the 2d curve.

      pointer Curve2dPtr to Curve2d from Adaptor2d;

      deferred class HCurve2d;
        ---Purpose: deferred class for the  2d curves manipulated with
        --          Handle.

      generic class GenHCurve2d;
      	---Purpose: Generic  class  used to create a  curve inheriting
      	--          from HCurve2d.

              

      --
      --  The  following  classes  are  used  to  define  an  abstract
      --  simplified  "topology"  for  surfaces.   This  is   used  by
      --  algorithm as mass properties or surface intersections.
      --  


      class Line2d;

      class HLine2d instantiates GenHCurve2d(Line2d from Adaptor2d);
	---Purpose: Use by the TopolTool to trim a surface.
    
      --
      --  The   following  classes  provides  algorithmic   curves and
      --  surface, they are inheriting from  Curve and Surface and the
      --  correponding HCurve and HSurface is instantiated.
      --  
      --  



end Adaptor2d;