Open CASCADE Technology 6.6.0
Public Member Functions
GeomConvert_CompBezierSurfacesToBSplineSurface Class Reference

An algorithm to convert a grid of adjacent
non-rational Bezier surfaces into a BSpline surface.
A CompBezierSurfacesToBSplineSurface object
provides a framework for:
More...

#include <GeomConvert_CompBezierSurfacesToBSplineSurface.hxx>

Public Member Functions

 GeomConvert_CompBezierSurfacesToBSplineSurface (const TColGeom_Array2OfBezierSurface &Beziers)
 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:

 GeomConvert_CompBezierSurfacesToBSplineSurface (const TColGeom_Array2OfBezierSurface &Beziers, const Standard_Real Tolerance, const Standard_Boolean RemoveKnots=Standard_True)
 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.

 GeomConvert_CompBezierSurfacesToBSplineSurface (const TColGeom_Array2OfBezierSurface &Beziers, const TColStd_Array1OfReal &UKnots, const TColStd_Array1OfReal &VKnots, const GeomAbs_Shape UContinuity=GeomAbs_C0, const GeomAbs_Shape VContinuity=GeomAbs_C0, const Standard_Real Tolerance=1.0e-4)
 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:

Standard_Integer NbUKnots () const
 Returns the number of knots in the U direction
of the BSpline surface whose data is computed in this framework.

Standard_Integer NbUPoles () const
 Returns number of poles in the U direction
of the BSpline surface whose data is computed in this framework.

Standard_Integer NbVKnots () const
 Returns the number of knots in the V direction
of the BSpline surface whose data is computed in this framework.

Standard_Integer NbVPoles () const
 Returns the number of poles in the V direction
of the BSpline surface whose data is computed in this framework.

const Handle_TColgp_HArray2OfPnt & Poles () const
 Returns the table of poles of the BSpline surface
whose data is computed in this framework.

const
Handle_TColStd_HArray1OfReal & 
UKnots () const
 Returns the knots table for the u parametric
direction of the BSpline surface whose data is computed in this framework.

Standard_Integer UDegree () const
 Returns the degree for the u parametric
direction of the BSpline surface whose data is computed in this framework.

const
Handle_TColStd_HArray1OfReal & 
VKnots () const
 Returns the knots table for the v parametric
direction of the BSpline surface whose data is computed in this framework.

Standard_Integer VDegree () const
 Returns the degree for the v parametric
direction of the BSpline surface whose data is computed in this framework.

const
Handle_TColStd_HArray1OfInteger & 
UMultiplicities () const
 Returns the multiplicities table for the u
parametric direction of the knots of the BSpline
surface whose data is computed in this framework.

const
Handle_TColStd_HArray1OfInteger & 
VMultiplicities () const
Standard_Boolean IsDone () const
 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.


Detailed Description


Constructor & Destructor Documentation

GeomConvert_CompBezierSurfacesToBSplineSurface::GeomConvert_CompBezierSurfacesToBSplineSurface ( const TColGeom_Array2OfBezierSurface Beziers)
  • 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.
GeomConvert_CompBezierSurfacesToBSplineSurface::GeomConvert_CompBezierSurfacesToBSplineSurface ( const TColGeom_Array2OfBezierSurface Beziers,
const Standard_Real  Tolerance,
const Standard_Boolean  RemoveKnots = Standard_True 
)
GeomConvert_CompBezierSurfacesToBSplineSurface::GeomConvert_CompBezierSurfacesToBSplineSurface ( const TColGeom_Array2OfBezierSurface Beziers,
const TColStd_Array1OfReal UKnots,
const TColStd_Array1OfReal VKnots,
const GeomAbs_Shape  UContinuity = GeomAbs_C0,
const GeomAbs_Shape  VContinuity = GeomAbs_C0,
const Standard_Real  Tolerance = 1.0e-4 
)
  • 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.

Member Function Documentation

Standard_Boolean GeomConvert_CompBezierSurfacesToBSplineSurface::IsDone ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::NbUKnots ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::NbUPoles ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::NbVKnots ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::NbVPoles ( ) const
const Handle_TColgp_HArray2OfPnt& GeomConvert_CompBezierSurfacesToBSplineSurface::Poles ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::UDegree ( ) const
const Handle_TColStd_HArray1OfReal& GeomConvert_CompBezierSurfacesToBSplineSurface::UKnots ( ) const
const Handle_TColStd_HArray1OfInteger& GeomConvert_CompBezierSurfacesToBSplineSurface::UMultiplicities ( ) const
Standard_Integer GeomConvert_CompBezierSurfacesToBSplineSurface::VDegree ( ) const
const Handle_TColStd_HArray1OfReal& GeomConvert_CompBezierSurfacesToBSplineSurface::VKnots ( ) const
const Handle_TColStd_HArray1OfInteger& GeomConvert_CompBezierSurfacesToBSplineSurface::VMultiplicities ( ) const

-- Returns the multiplicities table for the v
parametric direction of the knots of the BSpline
surface whose data is computed in this framework.


The documentation for this class was generated from the following file:
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines