GeomConvert_BSplineSurfaceToBezierSurface Class Reference

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: More...

#include <GeomConvert_BSplineSurfaceToBezierSurface.hxx>

Public Member Functions
	GeomConvert_BSplineSurfaceToBezierSurface (const Handle< Geom_BSplineSurface > &BasisSurface)
	Computes all the data needed to convert.
	GeomConvert_BSplineSurfaceToBezierSurface (const Handle< Geom_BSplineSurface > &BasisSurface, const Standard_Real U1, const Standard_Real U2, const Standard_Real V1, const Standard_Real V2, const Standard_Real ParametricTolerance)
	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.
Handle< Geom_BezierSurface >	Patch (const Standard_Integer UIndex, const Standard_Integer VIndex)
	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:
void	Patches (TColGeom_Array2OfBezierSurface &Surfaces)
	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:
void	UKnots (TColStd_Array1OfReal &TKnots) const
	This methode returns the bspline's u-knots associated to the converted Patches Raised if the length of Curves is not equal to NbUPatches + 1.
void	VKnots (TColStd_Array1OfReal &TKnots) const
	This methode returns the bspline's v-knots associated to the converted Patches Raised if the length of Curves is not equal to NbVPatches + 1.
Standard_Integer	NbUPatches () const
	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.
Standard_Integer	NbVPatches () const
	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.

Detailed Description

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

Constructor & Destructor Documentation

GeomConvert_BSplineSurfaceToBezierSurface() [1/2]

GeomConvert_BSplineSurfaceToBezierSurface::GeomConvert_BSplineSurfaceToBezierSurface

(

const Handle< Geom_BSplineSurface > &

BasisSurface

)

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.

GeomConvert_BSplineSurfaceToBezierSurface() [2/2]

GeomConvert_BSplineSurfaceToBezierSurface::GeomConvert_BSplineSurfaceToBezierSurface	(	const Handle< Geom_BSplineSurface > &	BasisSurface,
		const Standard_Real	U1,
		const Standard_Real	U2,
		const Standard_Real	V1,
		const Standard_Real	V2,
		const Standard_Real	ParametricTolerance
	)

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.

Member Function Documentation

NbUPatches()

Standard_Integer GeomConvert_BSplineSurfaceToBezierSurface::NbUPatches

(

)

const

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()

Standard_Integer GeomConvert_BSplineSurfaceToBezierSurface::NbVPatches

(

)

const

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.

Patch()

Handle< Geom_BezierSurface > GeomConvert_BSplineSurfaceToBezierSurface::Patch	(	const Standard_Integer	UIndex,
		const Standard_Integer	VIndex
	)

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).

Patches()

void GeomConvert_BSplineSurfaceToBezierSurface::Patches

(

TColGeom_Array2OfBezierSurface &

Surfaces

)

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.

UKnots()

void GeomConvert_BSplineSurfaceToBezierSurface::UKnots

(

TColStd_Array1OfReal &

TKnots

)

const

This methode returns the bspline's u-knots associated to the converted Patches Raised if the length of Curves is not equal to NbUPatches + 1.

VKnots()

void GeomConvert_BSplineSurfaceToBezierSurface::VKnots

(

TColStd_Array1OfReal &

TKnots

)

const

This methode returns the bspline's v-knots associated to the converted Patches Raised if the length of Curves is not equal to NbVPatches + 1.

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The documentation for this class was generated from the following file:

• GeomConvert_BSplineSurfaceToBezierSurface.hxx