-- File:	GeomConvert_BSplineSurfaceToBezierSurface.cdl
-- Created:	Tue Mar 12 17:21:39 1996
-- Author:	Bruno DUMORTIER
--		<dub@fuegox>
---Copyright:	 Matra Datavision 1996




class BSplineSurfaceToBezierSurface    from GeomConvert

        --- Purpose :
        --  This algorithm converts a B-spline surface into several  
        --  Bezier surfaces. It uses an algorithm of knot insertion.
    	-- A BSplineSurfaceToBezierSurface object provides a framework for:
    	-- -   defining the BSpline surface 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, 
    Array2OfBezierSurface from TColGeom,
    BezierSurface         from Geom,
    BSplineSurface        from Geom


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

    Create (BasisSurface : BSplineSurface)
    returns BSplineSurfaceToBezierSurface;
    	--- Purpose : Computes all the data needed to convert
    	-- -   the BSpline surface BasisSurface into a series of adjacent Bezier surfaces.
	-- The result consists of a grid of BasisSurface patches
    	-- limited by isoparametric curves corresponding to knot
    	-- values, both in the u and v parametric directions of
    	-- the surface. A row in the grid corresponds to a series
    	-- of adjacent patches, all limited by the same two
    	-- u-isoparametric curves. A column in the grid
    	-- corresponds to a series of adjacent patches, all
    	-- limited by the same two v-isoparametric curves.
    	-- Use the available interrogation functions to ascertain
    	-- the number of computed Bezier patches, and then to
    	-- construct each individual Bezier surface (or all Bezier surfaces).
    	-- Note: ParametricTolerance is not used.

    Create (BasisSurface        : BSplineSurface;  
            U1, U2, V1, V2      : Real; 
            ParametricTolerance : Real)
    returns BSplineSurfaceToBezierSurface
        --- Purpose : Computes all the data needed to convert
    	--   the patch of the BSpline surface BasisSurface
    	--   limited by the two parameter values U1 and U2 in
    	--   the u parametric direction, and by the two
    	--   parameter values V1 and V2 in the v parametric
    	--   direction, into a series of adjacent Bezier surfaces.
	-- The result consists of a grid of BasisSurface patches
    	-- limited by isoparametric curves corresponding to knot
    	-- values, both in the u and v parametric directions of
    	-- the surface. A row in the grid corresponds to a series
    	-- of adjacent patches, all limited by the same two
    	-- u-isoparametric curves. A column in the grid
    	-- corresponds to a series of adjacent patches, all
    	-- limited by the same two v-isoparametric curves.
    	-- Use the available interrogation functions to ascertain
    	-- the number of computed Bezier patches, and then to
    	-- construct each individual Bezier surface (or all Bezier surfaces).
    	-- Note: ParametricTolerance is not used.  Raises DomainError
        -- if U1 or U2 or V1 or V2 are out of the parametric bounds
        --  of the basis surface [FirstUKnotIndex, LastUKnotIndex] ,
        --  [FirstVKnotIndex, LastVKnotIndex] The tolerance criterion is
        --  ParametricTolerance.
        --  Raised if U2 - U1 <= ParametricTolerance or 
        --  V2 - V1 <= ParametricTolerance.  
    raises DomainError;
      

    Patch (me : in out; UIndex, VIndex : Integer)
    returns mutable BezierSurface
        --- Purpose : Constructs and returns the Bezier surface of indices
    	-- (UIndex, VIndex) to the patch grid computed on the
    	-- BSpline surface analyzed by this algorithm.
    	-- This Bezier surface has the same orientation as the
    	-- BSpline surface analyzed in this framework.
    	-- UIndex is an index common to a row in the patch
    	-- grid. A row in the grid corresponds to a series of
    	-- adjacent patches, all limited by the same two
    	-- u-isoparametric curves of the surface. VIndex is an
    	-- index common to a column in the patch grid. A column
    	-- in the grid corresponds to a series of adjacent
    	-- patches, all limited by the same two v-isoparametric
    	-- curves of the surface.
    	-- Exceptions
    	-- Standard_OutOfRange if:
    	-- -   UIndex is less than 1 or greater than the number
    	--   of rows in the patch grid computed on the BSpline
    	--   surface analyzed by this algorithm (as returned by
    	--   the function NbUPatches); or if
    	-- -   VIndex is less than 1 or greater than the number
    	--   of columns in the patch grid computed on the
    	--   BSpline surface analyzed by this algorithm (as
    	--   returned by the function NbVPatches).
          raises OutOfRange
           is static;
     
  
    Patches (me : in out; Surfaces : in out Array2OfBezierSurface)
    	--- Purpose : Constructs all the Bezier surfaces whose data is
    	-- computed by this algorithm, and loads them into the Surfaces table.
    	-- These Bezier surfaces have the same orientation as
    	-- the BSpline surface analyzed in this framework.
    	-- The Surfaces array is organised in the same way as
    	-- the patch grid computed on the BSpline surface
    	-- analyzed by this algorithm. A row in the array
    	-- corresponds to a series of adjacent patches, all
    	-- limited by the same two u-isoparametric curves of
    	-- the surface. A column in the array corresponds to a
    	-- series of adjacent patches, all limited by the same two
    	-- v-isoparametric curves of the surface.
    	-- Exceptions
    	-- Standard_DimensionError if the Surfaces array
    	-- was not created with the following bounds:
    	-- -   1, and the number of adjacent patch series in the
    	--   u parametric direction of the patch grid computed
    	--   on the BSpline surface, analyzed by this algorithm
    	--   (as given by the function NbUPatches) as row bounds,
    	-- -   1, and the number of adjacent patch series in the
    	--   v parametric direction of the patch grid computed
    	--   on the BSpline surface, analyzed by this algorithm
    	--   (as given by the function NbVPatches) as column bounds.
    raises DimensionError
          is static;
 
    UKnots(me;  TKnots  :  out  Array1OfReal from  TColStd)  
    	---Purpose: This methode returns the bspline's u-knots associated to
    	--          the converted Patches         
    raises DimensionError
        --- Purpose : Raised  if the length  of Curves is not equal to
        --  NbUPatches +  1.
    is static;
        
    VKnots(me;  TKnots  :  out  Array1OfReal from  TColStd)  
    	---Purpose: This methode returns the bspline's v-knots associated to
    	--          the converted Patches         
    raises DimensionError
        --- Purpose : Raised  if the length  of Curves is not equal to
        --  NbVPatches +  1.  
    is static; 
    
    NbUPatches (me)   returns Integer   is static;
        --- Purpose :
        --  Returns the number of Bezier surfaces in the U direction.
        --  If at the creation time you have decomposed the basis Surface
        --  between the parametric values UFirst, ULast the number of
        --  Bezier surfaces in the U direction depends on the number of
        --  knots included inside the interval [UFirst, ULast].
        --  If you have decomposed the whole basis B-spline surface the
        --  number of Bezier surfaces NbUPatches is equal to the number of
        --  UKnots less one. 


    NbVPatches (me)  returns Integer   is static;
        --- Purpose :
        --  Returns the number of Bezier surfaces in the V direction.
        --  If at the creation time you have decomposed the basis surface
        --  between the parametric values VFirst, VLast the number of
        --  Bezier surfaces in the V direction depends on the number of
        --  knots included inside the interval [VFirst, VLast].
        --  If you have decomposed the whole basis B-spline surface the
        --  number of Bezier surfaces NbVPatches is equal to the number of
        --  VKnots less one. 



fields  

  mySurface : BSplineSurface from Geom;
  
end BSplineSurfaceToBezierSurface;