OCCT/src/Convert/Convert.cdl

-- Created on: 1991-10-10
-- Created by: Jean Claude VAUTHIER
-- Copyright (c) 1991-1999 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 Convert

        --- Purpose: 
    	--The Convert package provides algorithms to convert the following into a BSpline curve or surface:
    	-- -   a bounded curve based on an elementary 2D curve (line, circle or conic) from the gp package,
    	-- -   a bounded surface based on an elementary surface (cylinder, cone, sphere or torus) from the gp package,
    	-- -   a series of adjacent 2D or 3D Bezier curves defined by their poles.
    	-- These algorithms compute the data needed to define the resulting BSpline curve or surface.
    	-- This elementary data (degrees, periodic characteristics, poles and weights, knots and
    	-- multiplicities) may then be used directly in an algorithm, or can be used to construct the curve
    	-- or the surface by calling the appropriate constructor provided by the classes
    	-- Geom2d_BSplineCurve, Geom_BSplineCurve or Geom_BSplineSurface.

uses TColStd, 
     TColgp,
     StdFail,
     gp,
     GeomAbs,
     TCollection

is

enumeration  ParameterisationType is
    TgtThetaOver2,
    TgtThetaOver2_1,
    TgtThetaOver2_2,
    TgtThetaOver2_3,
    TgtThetaOver2_4,
    	---Purpose: 
    	-- Identifies a type of parameterization of a circle or ellipse represented as a BSpline curve.
    	-- For a circle with a center C and a radius R (for example a Geom2d_Circle or a Geom_Circle),
    	-- the natural parameterization is angular. It uses the angle Theta made by the vector CM with
    	-- the 'X Axis' of the circle's local coordinate system as parameter for the current point M. The
    	-- coordinates of the point M are as follows:
	--     X   =   R *cos ( Theta )
	--     y   =   R * sin ( Theta )
    	--   Similarly, for an ellipse with a center C, a major radius R and a minor radius r, the circle Circ
    	-- with center C and radius R (and located in the same plane as the ellipse) lends its natural
    	-- angular parameterization to the ellipse. This is achieved by an affine transformation in the plane
    	-- of the ellipse, in the ratio r / R, about the 'X Axis' of its local coordinate system. The
    	-- coordinates of the current point M are as follows:
	--     X   =   R * cos ( Theta )
	--     y   =   r * sin ( Theta )
    	-- The process of converting a circle or an ellipse into a rational or non-rational BSpline curve
    	-- transforms the Theta angular parameter into a parameter t. This ensures the rational or
    	-- polynomial parameterization of the resulting BSpline curve. Several types of parametric
    	-- transformations are available.
    	-- TgtThetaOver2
    	-- The most usual method is Convert_TgtThetaOver2 where the parameter t on the BSpline
    	-- curve is obtained by means of transformation of the following type:
	--  t = tan ( Theta / 2 )
    	-- The result of this definition is:
	--  cos ( Theta ) = ( 1. - t**2 ) / ( 1. + t**2 )
        --  sin ( Theta ) =      2. * t / ( 1. + t**2 )
    	-- which ensures the rational parameterization of the circle or the ellipse. However, this is not the
    	-- most suitable parameterization method where the arc of the circle or ellipse has a large opening
    	-- angle. In such cases, the curve will be represented by a BSpline with intermediate knots. Each
    	-- span, i.e. each portion of curve between two different knot values, will use parameterization of
    	-- this type.
    	-- The number of spans is calculated using the following rule:
        --     ( 1.2 * Delta / Pi ) + 1
    	-- where Delta is equal to the opening angle (in radians) of the arc of the circle (Delta is
    	-- equal to 2.* Pi in the case of a complete circle).
    	-- The resulting BSpline curve is "exact", i.e. computing any point of parameter t on the BSpline
    	-- curve gives an exact point on the circle or the ellipse.
    	-- TgtThetaOver2_N
    	-- Where N is equal to 1, 2, 3 or 4, this ensures the same type of parameterization as
    	-- Convert_TgtThetaOver2 but sets the number of spans in the resulting BSpline curve to N
    	-- rather than allowing the algorithm to make this calculation.
    	-- However, the opening angle Delta (parametric angle, given in radians) of the arc of the circle
    	-- (or of the ellipse) must comply with the following:
    	-- -   Delta <= 0.9999 * Pi for the Convert_TgtThetaOver2_1 method, or
    	-- -   Delta <= 1.9999 * Pi for the Convert_TgtThetaOver2_2 method.
    	-- QuasiAngular
    	-- The Convert_QuasiAngular method of parameterization uses a different type of rational
    	-- parameterization. This method ensures that the parameter t along the resulting BSpline curve is
    	-- very close to the natural parameterization angle Theta of the circle or ellipse (i.e. which uses
    	-- the functions sin ( Theta ) and cos ( Theta ).
    	-- The resulting BSpline curve is "exact", i.e. computing any point of parameter t on the BSpline
    	-- curve gives an exact point on the circle or the ellipse.
    	-- RationalC1
    	-- The Convert_RationalC1 method of parameterization uses a further type of rational
    	-- parameterization. This method ensures that the equation relating to the resulting BSpline curve
    	-- has a "C1" continuous denominator, which is not the case with the above methods. RationalC1
    	-- enhances the degree of continuity at the junction point of the different spans of the curve.
    	-- The resulting BSpline curve is "exact", i.e. computing any point of parameter t on the BSpline
    	-- curve gives an exact point on the circle or the ellipse.
    	-- Polynomial
    	-- The Convert_Polynomial method is used to produce polynomial (i.e. non-rational)
    	-- parameterization of the resulting BSpline curve with 8 poles (i.e. a polynomial degree equal to 7).
    	-- However, the result is an approximation of the circle or ellipse (i.e. computing the point of
    	-- parameter t on the BSpline curve does not give an exact point on the circle or the ellipse).
        QuasiAngular,
        RationalC1,
        Polynomial;
   


  imported CosAndSinEvalFunction ;
       -- typedef void *CosAndSinEvalFunction(Standard_Real,
       -- const Standard_Integer,
       -- const TColgp_Array1OfPnt2d&
       -- const TColStd_Array1OfReal& 
       -- const TColStd_Array1OfInteger&
       -- Standard_Real Result[2]
       -- 
    	

  deferred class ConicToBSplineCurve;
        --- Purpose :
        --  Super class of the following classes :
  
     class CircleToBSplineCurve;
           --- Purpose : Converts a circle into a B-spline curve.
     
     class EllipseToBSplineCurve;
           --- Purpose : Converts an ellipse into a B-spline curve.
     
     class HyperbolaToBSplineCurve;
           --- Purpose : Converts an hyperbola into a B-spline curve.

     class ParabolaToBSplineCurve;
           --- Purpose : Converts a parabola into a B-spline curve.
     


     
  deferred class ElementarySurfaceToBSplineSurface;
        --  Super class of the following classes :
  
     class CylinderToBSplineSurface;
           --- Purpose : Converts a bounded cylinder into a B-spline surface.
     
     class ConeToBSplineSurface;
           --- Purpose : Converts a bounded cone into a B-spline surface.
     
     class TorusToBSplineSurface;
           --- Purpose : Converts a torus into a B-spline surface.
     
     class SphereToBSplineSurface;
           --- Purpose : Converts a sphere into a B-spline surface.


  
  class SequenceOfArray1OfPoles 
    instantiates Sequence from TCollection( HArray1OfPnt from TColgp); 
    
  class CompBezierCurvesToBSplineCurve;
	   ---Purpose: Converts a list of connecting BezierCurves
	   --          into a B-spline curve.
    
  alias SequenceOfArray1OfPoles2d is SequenceOfArray1OfPnt2d from TColgp;  
    
    
  class CompBezierCurves2dToBSplineCurve2d;
	   ---Purpose: Converts a list of connecting BezierCurves
	   --          into a B-spline curve.

  class CompPolynomialToPoles;
    	   ---Purpose: Convert a serie of Polynomial N-Dimensional
    	   --          Curves that are have continuity CM to an 
    	   --          N-Dimensional Bspline Curve that has continuity
    	   --          CM
    	   
  class GridPolynomialToPoles;
    	   ---Purpose: Convert a grid of Polynomial Surfaces
    	   --          that are have continuity CM to an 
    	   --          Bspline Surface that has continuity
    	   --          CM
	       	             
    	             
end Convert;