GetParamAtPoint Method

Description

Computes the parameter on the curve that corresponds to a given array of world space points in the coordinate system lying near the curve.

Syntax

Visual Basic
Public Sub GetParamAtPoint( _ ByVal NumPoints As Long, _ ByRef Points() As Double, _ ByRef GuessParams() As Double, _ ByRef MaxDeviations() As Double, _ ByRef Params() As Double, _ ByRef Flags() As Long _ )

Visual Basic

Public Sub GetParamAtPoint( _
   ByVal NumPoints As Long, _
   ByRef Points() As Double, _
   ByRef GuessParams() As Double, _
   ByRef MaxDeviations() As Double, _
   ByRef Params() As Double, _
   ByRef Flags() As Long _
)

Parameters

NumPoints: Specifies the number of points to be evaluated.
Points: Specifies the array of points that are close to the curve.
GuessParams: Specifies an array of parameters that are your initial approximations. Can be NULL if not known.
MaxDeviations: Pecifies the array of maximum deviation that has been allowed from the true point. Can be NULL if not required. Array to be allocated by the caller to hold nPoints doubles.
Params: Specifies the array of computed parameters. Array to be allocated by the caller to hold nPoints parameters.
Flags: Specifies the array of flags that indicate if there was any ambiguity about the computation. Can be NULL if not required. Possible values of the flag are: 0 (the parameter is unique), 1 (there are distinctly many solutions), and 2 (there are infinitely many solutions).

Remarks

It is possible that there is more than one possible parameter for a given point that satisfies this criterion (for example, if the center of the circle is input). This method will, however, return only one solution. A status indicator is output for each point evaluated to indicate any ambiguity. You should provide the input points on or very near the curve to prevent such ambiguity from arising. You can provide initial approximate parametric points to speed up some computations. If you cannot provide approximations, set the argument to NULL. If you choose to provide approximations, do so for all of the points.