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-- File: Convert_CompBezierCurvesToBSplineCurve.cdl
-- Created: Wed Oct 20 11:54:50 1993
-- Author: Bruno DUMORTIER
-- <dub@topsn3>
---Copyright: Matra Datavision 1993
class CompBezierCurvesToBSplineCurve from Convert
---Purpose: An algorithm to convert a sequence of adjacent
-- non-rational Bezier curves into a BSpline curve.
-- A CompBezierCurvesToBSplineCurve object provides a framework for:
-- - defining the sequence of adjacent non-rational Bezier
-- curves to be converted into a BSpline curve,
-- - implementing the computation algorithm, and
-- - consulting the results.
-- Warning
-- Do not attempt to convert rational Bezier curves using this type of algorithm.
uses
Array1OfReal from TColStd,
SequenceOfReal from TColStd,
SequenceOfInteger from TColStd,
Array1OfInteger from TColStd,
Array1OfPnt from TColgp,
SequenceOfPnt from TColgp,
SequenceOfArray1OfPoles from Convert
-------------------------------------------------------------------------
--- Don't forget to use the method Perform before accessing the Result.
-------------------------------------------------------------------------
raises
ConstructionError from Standard
is
Create ( AngularTolerance : Real = 1.0e-4 )
returns CompBezierCurvesToBSplineCurve from Convert;
---Purpose: Constructs a framework for converting a sequence of
-- adjacent non-rational Bezier curves into a BSpline curve.
-- Knots will be created on the computed BSpline curve at
-- each junction point of two consecutive Bezier curves. The
-- degree of continuity of the BSpline curve will be increased at
-- the junction point of two consecutive Bezier curves if their
-- tangent vectors at this point are parallel. AngularTolerance
-- (given in radians, and defaulted to 1.0 e-4) will be used
-- to check the parallelism of the two tangent vectors.
-- Use the following functions:
-- - AddCurve to define in sequence the adjacent Bezier
-- curves to be converted,
-- - Perform to compute the data needed to build the BSpline curve,
-- - and the available consultation functions to access the
-- computed data. This data may be used to construct the BSpline curve.
AddCurve( me : in out;
Poles : Array1OfPnt from TColgp)
is static;
--- Purpose: Adds the Bezier curve defined by the table of poles Poles, to
-- the sequence (still contained in this framework) of adjacent
-- Bezier curves to be converted into a BSpline curve.
-- Only polynomial (i.e. non-rational) Bezier curves are
-- converted using this framework.
-- If this is not the first call to the function (i.e. if this framework
-- still contains data in its Bezier curve sequence), the degree
-- of continuity of the BSpline curve will be increased at the
-- time of computation at the first point of the added Bezier
-- curve (i.e. the first point of the Poles table). This will be the
-- case if the tangent vector of the curve at this point is
-- parallel to the tangent vector at the end point of the
-- preceding Bezier curve in the Bezier curve sequence still
-- contained in this framework. An angular tolerance given at
-- the time of construction of this framework will be used to
-- check the parallelism of the two tangent vectors. This
-- checking procedure and all related computations will be
-- performed by the Perform function.
-- When the adjacent Bezier curve sequence is complete, use
-- the following functions:
-- - Perform to compute the data needed to build the BSpline curve,
-- - and the available consultation functions to access the
-- computed data. This data may be used to construct the BSpline curve.
-- Warning
-- The Bezier curve sequence treated by this framework is
-- automatically initialized with the first Bezier curve when the
-- function is first called. During subsequent use of this function,
-- ensure that the first point of the added Bezier curve (i.e. the
-- first point of the Poles table) is coincident with the last point
-- of the Bezier curve sequence (i.e. the last point of the
-- preceding Bezier curve in the sequence) still contained in
-- this framework. An error may occur at the time of
-- computation if this condition is not satisfied. Particular care
-- must be taken with respect to the above, as this condition is
-- not checked either when defining the Bezier curve
-- sequence or at the time of computation.
Perform(me: in out)
---Purpose: Computes all the data needed to build a BSpline curve
-- equivalent to the adjacent Bezier curve sequence still
-- contained in this framework.
-- A knot is inserted on the computed BSpline curve at the
-- junction point of two consecutive Bezier curves. The
-- degree of continuity of the BSpline curve will be increased
-- at the junction point of two consecutive Bezier curves if
-- their tangent vectors at this point are parallel. An angular
-- tolerance given at the time of construction of this
-- framework is used to check the parallelism of the two
-- tangent vectors.
-- Use the available consultation functions to access the
-- computed data. This data may then be used to construct
-- the BSpline curve.
-- Warning
-- Make sure that the curves in the Bezier curve sequence
-- contained in this framework are adjacent. An error may
-- occur at the time of computation if this condition is not
-- satisfied. Particular care must be taken with respect to the
-- above as this condition is not checked, either when
-- defining the Bezier curve sequence or at the time of computation.
is static;
Degree(me) returns Integer from Standard
is static;
---Purpose: Returns the degree of the BSpline curve whose data is
-- computed in this framework.
-- Warning
-- Take particular care not to use this function before the
-- computation is performed (Perform function), as this
-- condition is not checked and an error may therefore occur.
NbPoles(me) returns Integer from Standard
is static;
---Purpose: Returns the number of poles of the BSpline curve whose
-- data is computed in this framework.
-- Warning
-- Take particular care not to use this function before the
-- computation is performed (Perform function), as this
-- condition is not checked and an error may therefore occur.
Poles(me; Poles : in out Array1OfPnt from TColgp)
is static;
--- Purpose: Loads the Poles table with the poles of the BSpline curve
-- whose data is computed in this framework.
-- Warning
-- - Do not use this function before the computation is
-- performed (Perform function).
-- - The length of the Poles array must be equal to the
-- number of poles of the BSpline curve whose data is
-- computed in this framework.
-- Particular care must be taken with respect to the above, as
-- these conditions are not checked, and an error may occur.
NbKnots(me) returns Integer from Standard
is static;
---Purpose: Returns the number of knots of the BSpline curve whose
-- data is computed in this framework.
-- Warning
-- Take particular care not to use this function before the
-- computation is performed (Perform function), as this
-- condition is not checked and an error may therefore occur.
KnotsAndMults(me;
Knots : in out Array1OfReal from TColStd;
Mults : in out Array1OfInteger from TColStd)
is static;
---Purpose:
-- - loads the Knots table with the knots,
-- - and loads the Mults table with the corresponding multiplicities
-- of the BSpline curve whose data is computed in this framework.
-- Warning
-- - Do not use this function before the computation is
-- performed (Perform function).
-- - The length of the Knots and Mults arrays must be equal
-- to the number of knots in the BSpline curve whose data is
-- computed in this framework.
-- Particular care must be taken with respect to the above as
-- these conditions are not checked, and an error may occur.
fields
mySequence : SequenceOfArray1OfPoles from Convert;
CurvePoles : SequenceOfPnt from TColgp;
CurveKnots : SequenceOfReal from TColStd;
KnotsMultiplicities : SequenceOfInteger from TColStd;
myDegree : Integer from Standard;
myAngular : Real from Standard;
myDone : Boolean from Standard;
end CompBezierCurvesToBSplineCurve;
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