-- File:	 BSplineCurveKnotSplitting.cdl
-- Created:	 Thu Oct  3 15:54:16 1991
---Copyright:	 Matra Datavision 1991, 1992





class BSplineCurveKnotSplitting   from GeomConvert



        --- Purpose : An algorithm to determine points at which a BSpline
    	-- curve should be split in order to obtain arcs of the same continuity.
    	-- If you require curves with a minimum continuity for
    	-- your computation, it is useful to know the points
    	-- between which an arc has a continuity of a given
    	-- order. For a BSpline curve, the discontinuities are
    	-- localized at the knot values. Between two knot values
    	-- the BSpline is infinitely and continuously
    	-- differentiable. At a given knot, the continuity is equal
    	-- to: Degree - Mult, where Degree is the
    	-- degree of the BSpline curve and Mult is the multiplicity of the knot.
    	-- It is possible to compute the arcs which correspond to
    	-- this splitting using the global function
    	-- SplitBSplineCurve provided by the package GeomConvert.
    	-- A BSplineCurveKnotSplitting object provides a framework for:
    	-- -   defining the curve to be analyzed and the
    	--   required degree of continuity,
    	-- -   implementing the computation algorithm, and
    	-- -   consulting the results.




uses  Array1OfInteger      from TColStd,
      HArray1OfInteger      from TColStd,
      BSplineCurve         from Geom


raises DimensionError from Standard, 
       RangeError     from Standard
  
is


  Create (BasisCurve : BSplineCurve from Geom; ContinuityRange : Integer)
     returns BSplineCurveKnotSplitting
        --- Purpose : Determines points at which the BSpline curve
    	-- BasisCurve should be split in order to obtain arcs
    	-- with a degree of continuity equal to ContinuityRange.
    	-- These points are knot values of BasisCurve. They
    	-- are identified by indices in the knots table of BasisCurve.
    	-- Use the available interrogation functions to access
    	-- computed values, followed by the global function
    	-- SplitBSplineCurve (provided by the package GeomConvert) to split the curve.
    	-- Exceptions
    	-- Standard_RangeError if ContinuityRange is less than zero.
           raises RangeError;
      

  
  NbSplits (me)    returns Integer   is static;
        --- Purpose :Returns the number of points at which the analyzed
    	-- BSpline curve should be split, in order to obtain arcs
    	-- with the continuity required by this framework.
    	-- All these points correspond to knot values. Note that
    	-- the first and last points of the curve, which bound the
    	-- first and last arcs, are counted among these splitting points.


  Splitting (me; SplitValues : in out Array1OfInteger)
        --- Purpose : Loads the SplitValues table with the split knots
    	-- values computed in this framework. Each value in the
    	-- table is an index in the knots table of the BSpline
    	-- curve analyzed by this algorithm.
    	-- The values in SplitValues are given in ascending
    	-- order and comprise the indices of the knots which
    	-- give the first and last points of the curve. Use two
    	-- consecutive values from the table as arguments of the
    	-- global function SplitBSplineCurve (provided by the
    	-- package GeomConvert) to split the curve.
    	-- Exceptions
    	-- Standard_DimensionError if the array SplitValues
    	-- was not created with the following bounds:
    	-- -   1, and
    	-- -   the number of split points computed in this
    	--   framework (as given by the function NbSplits).
     raises DimensionError
            is static;


  SplitValue (me; Index : Integer)   returns Integer
        --- Purpose : Returns the split knot of index Index to the split knots
    	-- table computed in this framework. The returned value
    	-- is an index in the knots table of the BSpline curve
    	-- analyzed by this algorithm.
    	-- Notes:
    	-- -   If Index is equal to 1, the corresponding knot
    	--   gives the first point of the curve.
    	-- -   If Index is equal to the number of split knots
    	--   computed in this framework, the corresponding
    	--   point is the last point of the curve.
    	-- Exceptions
    	-- Standard_RangeError if Index is less than 1 or
    	-- greater than the number of split knots computed in this framework.
     raises RangeError
    is static;


              
fields  

  splitIndexes : HArray1OfInteger;

end BSplineCurveKnotSplitting;