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-- File: Geom2d_BSplineCurve.cdl
-- Created: Wed Mar 24 17:35:29 1993
-- Author: DUB
-- <DUB@fuegox>
-- Copyright: Matra Datavision 1993
class BSplineCurveToBezierCurve from Geom2dConvert
--- Purpose :An algorithm to convert a BSpline curve into a series
-- of adjacent Bezier curves.
-- A BSplineCurveToBezierCurve object provides a framework for:
-- - defining the BSpline curve 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,
Array1OfBezierCurve from TColGeom2d,
BezierCurve from Geom2d,
BSplineCurve from Geom2d
raises
DimensionError from Standard,
DomainError from Standard,
OutOfRange from Standard
is
Create (BasisCurve : BSplineCurve) returns BSplineCurveToBezierCurve;
--- Purpose : Computes all the data needed to convert
-- - the BSpline curve BasisCurve, into a series of adjacent Bezier arcs.
-- The result consists of a series of BasisCurve arcs
-- limited by points corresponding to knot values of the curve.
-- Use the available interrogation functions to ascertain
-- the number of computed Bezier arcs, and then to
-- construct each individual Bezier curve (or all Bezier curves).
-- Note: ParametricTolerance is not used.
Create (BasisCurve : BSplineCurve;
U1, U2 : Real;
ParametricTolerance : Real)
returns BSplineCurveToBezierCurve
--- Purpose : Computes all the data needed to convert
-- the portion of the BSpline curve BasisCurve
-- limited by the two parameter values U1 and U2
-- for Example if there is a Knot Uk and
-- Uk < U < Uk + ParametricTolerance/2 the last curve
-- corresponds to the span [Uk-1, Uk] and not to [Uk, Uk+1]
-- The result consists of a series of BasisCurve arcs
-- limited by points corresponding to knot values of the curve.
-- Use the available interrogation functions to ascertain
-- the number of computed Bezier arcs, and then to
-- construct each individual Bezier curve (or all Bezier curves).
-- Note: ParametricTolerance is not used.
-- Raises DomainError if U1 or U2 are out of the parametric bounds of the basis
-- curve [FirstParameter, LastParameter]. The Tolerance criterion
-- is ParametricTolerance.
-- Raised if Abs (U2 - U1) <= ParametricTolerance.
raises DomainError;
Arc (me : in out; Index : Integer) returns mutable BezierCurve
--- Purpose :Constructs and returns the Bezier curve of index
-- Index to the table of adjacent Bezier arcs
-- computed by this algorithm.
-- This Bezier curve has the same orientation as the
-- BSpline curve analyzed in this framework.
-- Exceptions
-- Standard_OutOfRange if Index is less than 1 or
-- greater than the number of adjacent Bezier arcs
-- computed by this algorithm.
raises OutOfRange
is static;
Arcs (me : in out; Curves : in out Array1OfBezierCurve)
--- Purpose :Constructs all the Bezier curves whose data is
-- computed by this algorithm and loads these curves
-- into the Curves table.
-- The Bezier curves have the same orientation as the
-- BSpline curve analyzed in this framework.
-- Exceptions
-- Standard_DimensionError if the Curves array was
-- not created with the following bounds:
-- - 1 , and
-- - the number of adjacent Bezier arcs computed by
-- this algorithm (as given by the function NbArcs).
raises DimensionError
is static;
Knots(me; TKnots : out Array1OfReal from TColStd)
---Purpose: This methode returns the bspline's knots associated to
-- the converted arcs
-- Raises DimensionError if the length of Curves is not equal to
-- NbArcs + 1
raises DimensionError
is static;
NbArcs (me) returns Integer is static;
--- Purpose :
-- Returns the number of BezierCurve arcs.
-- If at the creation time you have decomposed the basis curve
-- between the parametric values UFirst, ULast the number of
-- BezierCurve arcs depends on the number of knots included inside
-- the interval [UFirst, ULast].
-- If you have decomposed the whole basis B-spline curve the number
-- of BezierCurve arcs NbArcs is equal to the number of knots less
-- one.
fields
myCurve : BSplineCurve from Geom2d;
end BSplineCurveToBezierCurve;
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