path: root/src/GeomConvert/GeomConvert_CompBezierSurfacesToBSplineSurface.cdl

-- File:	GeomConvert_CompBezierSurfaceToBSplineSurfaces.cdl
-- Created:	Thu Jun  6 18:11:13 1996
-- Author:	Philippe MANGIN
--		<pmn@sgi29>
---Copyright:	 Matra Datavision 1996


class CompBezierSurfacesToBSplineSurface from GeomConvert 

	---Purpose: An algorithm to convert a grid of adjacent
    	-- non-rational Bezier surfaces into a BSpline surface.
    	-- A CompBezierSurfacesToBSplineSurface object
    	-- provides a framework for:
    	-- -   defining the grid of adjacent Bezier surfaces
    	--   which is to be converted into a BSpline surface,
    	-- -   implementing the computation algorithm, and
    	-- -   consulting the results.
    	-- Warning
    	-- Do not attempt to convert rational Bezier surfaces using such an algorithm.
    	-- Input is array of Bezier patch        
        --           1    2    3     4  -> VIndex [1, NbVPatches] -> VDirection
        --         -----------------------
        --    1    |    |    |    |      |
        --         -----------------------
        --    2    |    |    |    |      |
        --         -----------------------
        --    3    |    |    |    |      |
        --         -----------------------
        --  UIndex [1, NbUPatches]  Udirection  
        --         
    	--  Warning! Patches must have compatible parametrization
	
uses  
    Array2OfBezierSurface from TColGeom,
    HArray2OfPnt from TColgp,
    Array1OfReal from TColStd,
    HArray1OfReal from TColStd,
    Shape from GeomAbs,
    HArray1OfInteger from TColStd

raises
    DimensionError    from Standard,
    NotImplemented    from Standard,
    ConstructionError from Standard

is
 Create(Beziers          :  Array2OfBezierSurface) 
    	---Purpose :  Computes all the data needed to build a "C0"
    	-- continuous BSpline surface equivalent to the grid of
    	-- adjacent non-rational Bezier surfaces Beziers.
    	-- Each surface in the Beziers grid becomes a natural
    	-- patch, limited by knots values, on the BSpline surface
    	-- whose data is computed. Surfaces in the grid must
    	-- satisfy the following conditions:
    	-- -   Coincident bounding curves between two
    	--   consecutive surfaces in a row of the Beziers grid
    	--   must be u-isoparametric bounding curves of these two surfaces.
    	-- -   Coincident bounding curves between two
    	--   consecutive surfaces in a column of the Beziers
    	--   grid must be v-isoparametric bounding curves of these two surfaces.
    	--   The BSpline surface whose data is computed has the
    	-- following characteristics:
    	-- -   Its degree in the u (respectively v) parametric
    	--   direction is equal to that of the Bezier surface
    	--   which has the highest degree in the u
    	--   (respectively v) parametric direction in the Beziers grid.
    	-- -   It is a "Piecewise Bezier" in both u and v
    	--   parametric directions, i.e.:
    	--   -   the knots are regularly spaced in each
    	--    parametric direction (i.e. the difference between
    	--    two consecutive knots is a constant), and
    	--   -   all the multiplicities of the surface knots in a
    	--    given parametric direction are equal to
    	--    Degree, which is the degree of the BSpline
    	--    surface in this parametric direction, except for
    	--    the first and last knots for which the multiplicity is
    	--    equal to Degree + 1.
    	-- -   Coincident bounding curves between two
    	--   consecutive columns of Bezier surfaces in the
    	--   Beziers grid become u-isoparametric curves,
    	--   corresponding to knots values of the BSpline surface.
    	-- -   Coincident bounding curves between two
    	--   consecutive rows of Bezier surfaces in the Beziers
    	--   grid become v-isoparametric curves
    	--   corresponding to knots values of the BSpline surface.
    	--  Use the available consultation functions to access the
    	--  computed data. This data may be used to construct the BSpline surface.
    	-- Warning
    	-- The surfaces in the Beziers grid must be adjacent, i.e.
    	-- two consecutive Bezier surfaces in the grid (in a row
    	-- or column) must have a coincident bounding curve. In
    	-- addition, the location of the parameterization on each
    	-- of these surfaces (i.e. the relative location of u and v
    	-- isoparametric curves on the surface) is of importance
    	-- with regard to the positioning of the surfaces in the
    	-- Beziers grid. Care must be taken with respect to the
    	-- above, as these properties are not checked and an
    	-- error may occur if they are not satisfied.
    	-- Exceptions
    	-- Standard_NotImplemented if one of the Bezier
    	-- surfaces of the Beziers grid is rational.       
 returns CompBezierSurfacesToBSplineSurface
 raises NotImplemented; 
  
 Create(Beziers          :  Array2OfBezierSurface; 
        Tolerance        :  Real; 
        RemoveKnots      :  Boolean  =  Standard_True) 
    	---Purpose : Build an Ci uniform (Rational) BSpline surface
    	--           The higest Continuity Ci is imposed, like the
    	--           maximal deformation is lower than <Tolerance>. 
    	--  Warning:  The Continuity C0 is imposed without any check.    
 returns CompBezierSurfacesToBSplineSurface
 raises NotImplemented;

 Create(Beziers          :  Array2OfBezierSurface;
        UKnots           :  Array1OfReal;
	VKnots           :  Array1OfReal;
        UContinuity      :  Shape = GeomAbs_C0;
        VContinuity      :  Shape = GeomAbs_C0;
        Tolerance        :  Real  = 1.0e-4)
    	---Purpose :  Computes all the data needed to construct a BSpline
    	-- surface equivalent to the adjacent non-rational
    	-- Bezier surfaces Beziers grid.
    	-- Each surface in the Beziers grid becomes a natural
    	-- patch, limited by knots values, on the BSpline surface
    	-- whose data is computed. Surfaces in the grid must
    	-- satisfy the following conditions:
    	-- -   Coincident bounding curves between two
    	--   consecutive surfaces in a row of the Beziers grid
    	--   must be u-isoparametric bounding curves of these two surfaces.
    	-- -   Coincident bounding curves between two
    	--   consecutive surfaces in a column of the Beziers
    	-- grid must be v-isoparametric bounding curves of these two surfaces.
    	--   The BSpline surface whose data is computed has the
    	-- following characteristics:
    	-- -   Its degree in the u (respectively v) parametric
    	--   direction is equal to that of the Bezier surface
    	--   which has the highest degree in the u
    	--   (respectively v) parametric direction in the Beziers grid.
    	-- -   Coincident bounding curves between two
    	--   consecutive columns of Bezier surfaces in the
    	--   Beziers grid become u-isoparametric curves
    	--   corresponding to knots values of the BSpline surface.
    	-- -   Coincident bounding curves between two
    	--   consecutive rows of Bezier surfaces in the Beziers
    	--   grid become v-isoparametric curves
    	--   corresponding to knots values of the BSpline surface.
    	-- Knots values of the BSpline surface are given in the two tables:
    	-- -   UKnots for the u parametric direction (which
    	--   corresponds to the order of Bezier surface columns in the Beziers grid), and
    	-- -   VKnots for the v parametric direction (which
    	--  corresponds to the order of Bezier surface rows in the Beziers grid).
    	--   The dimensions of UKnots (respectively VKnots)
    	-- must be equal to the number of columns (respectively,
    	-- rows) of the Beziers grid, plus 1 .
    	-- UContinuity and VContinuity, which are both
    	-- defaulted to GeomAbs_C0, specify the required
    	-- continuity on the BSpline surface. If the required
    	-- degree of continuity is greater than 0 in a given
    	-- parametric direction, a deformation is applied locally
    	-- on the initial surface (as defined by the Beziers grid)
    	-- to satisfy this condition. This local deformation is not
    	-- applied however, if it is greater than Tolerance
    	-- (defaulted to 1.0 e-7). In such cases, the
    	-- continuity condition is not satisfied, and the function
    	-- IsDone will return false. A small tolerance value
    	-- prevents any modification of the surface and a large
    	-- tolerance value "smoothes" the surface.
    	-- Use the available consultation functions to access the
    	-- computed data. This data may be used to construct the BSpline surface.
    	-- Warning
    	-- The surfaces in the Beziers grid must be adjacent, i.e.
    	-- two consecutive Bezier surfaces in the grid (in a row
    	-- or column) must have a coincident bounding curve. In
    	-- addition, the location of the parameterization on each
    	-- of these surfaces (i.e. the relative location of u and v
    	-- isoparametric curves on the surface) is of importance
    	-- with regard to the positioning of the surfaces in the
    	-- Beziers grid. Care must be taken with respect to the
    	-- above, as these properties are not checked and an
    	-- error may occur if they are not satisfied.
    	-- Exceptions
    	-- Standard_DimensionMismatch:
    	-- -   if the number of knots in the UKnots table (i.e. the
    	--   length of the UKnots array) is not equal to the
    	--   number of columns of Bezier surfaces in the
    	--   Beziers grid plus 1, or
    	-- -   if the number of knots in the VKnots table (i.e. the
    	--   length of the VKnots array) is not equal to the
    	--   number of rows of Bezier surfaces in the Beziers grid, plus 1.
    	--   Standard_ConstructionError:
    	-- -   if UContinuity and VContinuity are not equal to
    	--   one of the following values: GeomAbs_C0,
    	--   GeomAbs_C1, GeomAbs_C2 and GeomAbs_C3; or
    	-- -   if the number of columns in the Beziers grid is
    	--   greater than 1, and the required degree of
    	--   continuity in the u parametric direction is greater
    	--   than that of the Bezier surface with the highest
    	--   degree in the u parametric direction (in the Beziers grid), minus 1; or
    	-- -   if the number of rows in the Beziers grid is
    	--   greater than 1, and the required degree of
    	--   continuity in the v parametric direction is greater
    	--   than that of the Bezier surface with the highest
    	--   degree in the v parametric direction (in the Beziers grid), minus 1 .
    	--   Standard_NotImplemented if one of the Bezier
    	-- surfaces in the Beziers grid is rational.
 returns CompBezierSurfacesToBSplineSurface 
 raises ConstructionError,
        DimensionError,    
	NotImplemented;  
  
 Perform (me : in out; Beziers : Array2OfBezierSurface) 
    	---Purpose :  It used internaly by the constructors. 
 is private;

 NbUKnots (me)   returns Integer;
       	---Purpose :  Returns the number of knots in the U direction 
       	-- of the BSpline surface whose data is computed in this framework.
    	---C++: inline

 NbUPoles (me)  returns Integer;
     	---Purpose : Returns number of poles in the U direction
     	-- of the BSpline surface whose data is computed in this framework. 
     	---C++: inline

 NbVKnots (me)  returns Integer;
        ---Purpose : Returns the number of knots in the V direction
    	-- of the BSpline surface whose data is computed in this framework.   
        ---C++: inline

 NbVPoles (me)  returns Integer;
        ---Purpose : Returns the number of poles in the V direction
        -- of the BSpline surface whose data is computed in this framework.     
        ---C++: inline
 
 Poles(me)
     	---Purpose :  Returns the table of poles of the BSpline surface
     	-- whose data is computed in this framework.
     	---C++: inline
     	---C++: return const & 
     returns HArray2OfPnt;

   
 UKnots (me)
    	---Purpose : Returns the knots table for the u parametric
    	-- direction of the BSpline surface whose data is computed in this framework.
    	---C++: inline
     	---C++: return const &
    	returns  HArray1OfReal;
   
 UDegree (me)  returns Integer;
        ---Purpose : Returns the degree for the u  parametric
    	-- direction of the BSpline surface whose data is computed in this framework.
        ---C++: inline

 VKnots (me)
    	---Purpose : Returns the knots table for the v parametric
    	-- direction of the BSpline surface whose data is computed in this framework.     	
    	---C++: inline
     	---C++: return const &
    	returns HArray1OfReal;      
      
       
 VDegree (me) 
    	---Purpose : Returns the degree for the v  parametric
    	-- direction of the BSpline surface whose data is computed in this framework.
    	---C++: inline
    returns Integer;

 UMultiplicities (me)
        ---Purpose :  
    	-- Returns the multiplicities table for the u 
        -- parametric direction of the knots of the BSpline
    	-- surface whose data is computed in this framework.
    	---C++: inline
        ---C++: return const &
 returns  HArray1OfInteger;

 VMultiplicities (me)
     	---Purpose : -- Returns the multiplicities table for the v 
        -- parametric direction of the knots of the BSpline
    	-- surface whose data is computed in this framework.
    	---C++: inline
	---C++: return const &
     returns  HArray1OfInteger;

 IsDone(me) 
    	---Purpose : Returns true if the conversion was successful.
    	-- Unless an exception was raised at the time of
    	-- construction, the conversion of the Bezier surface
    	-- grid assigned to this algorithm is always carried out.
    	-- IsDone returns false if the constraints defined at the
    	-- time of construction cannot be respected. This occurs
    	-- when there is an incompatibility between a required
    	-- degree of continuity on the BSpline surface, and the
    	-- maximum tolerance accepted for local deformations
    	-- of the surface. In such a case the computed data
    	-- does not satisfy all the initial constraints.
 returns Boolean ;	


fields
myUDegree    : Integer;
myVDegree    : Integer;
myVMults     : HArray1OfInteger;
myUMults     : HArray1OfInteger;
myUKnots     : HArray1OfReal;
myVKnots     : HArray1OfReal;
myPoles      : HArray2OfPnt;
isrational   : Boolean;
myDone       : Boolean;

end CompBezierSurfacesToBSplineSurface;