Function IConvertPcurveToBcurveSize( _
   ByVal Dim As Integer, _
   ByVal Order As Integer, _
   ByVal Nsegs As Integer, _
   ByRef Coeffs As Double, _
   ByVal Basis As Integer, _
   ByRef Xform As Double, _
   ByVal ScaleFactor As Double _
) As Integer

Dim instance As ICurve
Dim Dim As Integer
Dim Order As Integer
Dim Nsegs As Integer
Dim Coeffs As Double
Dim Basis As Integer
Dim Xform As Double
Dim ScaleFactor As Double
Dim value As Integer
 
value = instance.IConvertPcurveToBcurveSize(Dim, Order, Nsegs, Coeffs, Basis, Xform, ScaleFactor)

int IConvertPcurveToBcurveSize( 
   int Dim,
   int Order,
   int Nsegs,
   ref double Coeffs,
   int Basis,
   ref double Xform,
   double ScaleFactor
)

int IConvertPcurveToBcurveSize( 
&   int Dim,
&   int Order,
&   int Nsegs,
&   double% Coeffs,
&   int Basis,
&   double% Xform,
&   double ScaleFactor
) 

Parameters

Dim

Dimension of the curve:

• 3 = nonrational

• 4 = rational

Order

Order of the curve; minimum is 2 (linear)

Nsegs

Number of segments in the curve; must be at least 1

Coeffs

Array of coefficients

Basis

0; not currently used

Xform

Transformation matrix to apply after conversion to b-curve

ScaleFactor

Units conversion factor to apply after conversion to b-curve

Return Value

Indicates that conversion succeeded or failed

Dimension of coefficient vectors dim:

• For rational curves dim = 4.

• For non-rational curves dim = 3.

Order of each segment of the curve order:

1. The order of the curve = degree + 1.

2. The minimum order is 2.

Number of segments in the curve nseg:

• There must be at least one segment (nseg >= 1).

• Adjacent segments must meet.

Coefficient data coeffs:

• Contains order * nseg vectors of dimension dim. If dim = 3, then the vectors are 3-D vectors giving the x, y and z components. If dim = 4, then each vector has a weight (w) associated with it, and x, y, z and w components are supplied for each vector. The weights supplied must be greater than 0.

• The coefficients are supplied in order, segment by segment.

• The interpretation of the coefficients depends on the representation method chosen; this is determined by the value of the argument basis.

Representation method basis:

The expressions for each segment of the B-curve P(t) in the various representations are shown next. For generality, the rational form is given.

The simplification to the non-rational form can be obtained by setting both the weights and the denominator equal to 1.0

Polynomial coefficients:

The curve equation is given by a rational polynomial of order 'order':

                        n                     n

                        --         i        / --     i

          P(t)   =   >   w  A  t     /   >  w  t

                        --   i  i    /        --  i

                        i=0                 i=0

          where n = order-1

                A = polynomial coefficient

                  i

                w = weight for A

                  i              i

The polynomial coefficients are supplied starting with the constant  term and ending with the term of highest degree.