-- File:	Geom2d_BSplineCurve.cdl
-- Created:	Wed Mar 24 17:35:29 1993
-- Author:	DUB
--		<DUB@fuegox>
-- Copyright:	 Matra Datavision 1993

class BSplineCurveToBezierCurve   from Geom2dConvert 

        --- Purpose :An algorithm to convert a BSpline curve into a series
    	-- of adjacent Bezier curves.
    	-- A BSplineCurveToBezierCurve object provides a framework for:
    	-- -   defining the BSpline curve to be converted
    	-- -   implementing the construction algorithm, and
    	-- -   consulting the results.
        --  References :
        --  Generating the Bezier points of B-spline curves and surfaces
        --  (Wolfgang Bohm) CAD volume 13 number 6 november 1981


uses   
    Array1OfReal        from TColStd, 
    Array1OfBezierCurve from TColGeom2d,
    BezierCurve         from Geom2d,
    BSplineCurve        from Geom2d


raises 
    DimensionError    from Standard,
    DomainError       from Standard,
    OutOfRange        from Standard
  
is


    Create (BasisCurve : BSplineCurve)  returns BSplineCurveToBezierCurve;
        --- Purpose : Computes all the data needed to convert
    	-- -   the BSpline curve BasisCurve, into a series of adjacent Bezier arcs.
    	-- The result consists of a series of BasisCurve arcs
    	-- limited by points corresponding to knot values of the curve.
    	-- Use the available interrogation functions to ascertain
    	-- the number of computed Bezier arcs, and then to
    	-- construct each individual Bezier curve (or all Bezier curves).
    	-- Note: ParametricTolerance is not used.
      
    Create (BasisCurve : BSplineCurve; 
    	    U1, U2     : Real; 
    	    ParametricTolerance : Real)
    returns BSplineCurveToBezierCurve
        --- Purpose : Computes all the data needed to convert
    	--        the portion of the BSpline curve BasisCurve
    	--   limited by the two parameter values U1 and U2
    	--       for Example if there is a Knot Uk and
        --  Uk < U < Uk + ParametricTolerance/2 the last curve
        --  corresponds to the span [Uk-1, Uk] and not to  [Uk, Uk+1]
        -- The result consists of a series of BasisCurve arcs
    	-- limited by points corresponding to knot values of the curve.
    	-- Use the available interrogation functions to ascertain
    	-- the number of computed Bezier arcs, and then to
    	-- construct each individual Bezier curve (or all Bezier curves).
    	-- Note: ParametricTolerance is not used.
    	--  Raises DomainError if U1 or U2 are out of the parametric bounds of the basis
        --  curve [FirstParameter, LastParameter]. The Tolerance criterion
        --  is ParametricTolerance.
        --  Raised if Abs (U2 - U1) <= ParametricTolerance.
    raises DomainError;
   
        
    Arc (me : in out; Index : Integer)    returns mutable BezierCurve
        --- Purpose :Constructs and returns the Bezier curve of index
    	-- Index to the table of adjacent Bezier arcs
    	-- computed by this algorithm.
    	-- This Bezier curve has the same orientation as the
    	-- BSpline curve analyzed in this framework.
    	-- Exceptions
    	-- Standard_OutOfRange if Index is less than 1 or
    	-- greater than the number of adjacent Bezier arcs
    	-- computed by this algorithm.
    raises OutOfRange
    is static;
     
  
    Arcs (me : in out; Curves : in out Array1OfBezierCurve)
        --- Purpose :Constructs all the Bezier curves whose data is
    	-- computed by this algorithm and loads these curves
    	-- into the Curves table.
    	-- The Bezier curves have the same orientation as the
    	-- BSpline curve analyzed in this framework.
    	-- Exceptions
    	-- Standard_DimensionError if the Curves array was
    	-- not created with the following bounds:
    	-- -   1 , and
    	-- -   the number of adjacent Bezier arcs computed by
    	--   this algorithm (as given by the function NbArcs).
    raises DimensionError
         is static;
 
    Knots(me;  TKnots  :  out  Array1OfReal from  TColStd)  
    	---Purpose: This methode returns the bspline's knots associated to
	--          the converted arcs 
	-- Raises DimensionError if the length  of Curves is not equal to
        --  NbArcs +  1       
    raises DimensionError
           is static;    

    NbArcs (me)   returns Integer   is static;
        --- Purpose :
        --  Returns the number of BezierCurve arcs.
        --  If at the creation time you have decomposed the basis curve
        --  between the parametric values UFirst, ULast the number of
        --  BezierCurve arcs depends on the number of knots included inside
        --  the interval [UFirst, ULast].
        --  If you have decomposed the whole basis B-spline curve the number 
        --  of BezierCurve arcs NbArcs is equal to the number of knots less
        --  one.

fields  

  myCurve  : BSplineCurve from Geom2d; 
end BSplineCurveToBezierCurve;