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-- 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;
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