vlax-curve-getFirstDeriv

vlax-curve-getEndPoint

V Functions

vlax-curve-getParamAtDist

 

AutoLISP Reference Guide > AutoLISP Functions > V Functions > 

vlax-curve-getFirstDeriv

Returns the first derivative (in WCS) of a curve at the specified location

(vlax-curve-getFirstDeriv curve-obj param)

Arguments

curve-obj

The VLA-object to be measured.

param

A number specifying a parameter on the curve.

Return Values

A 3D vector list, if successful; otherwise nil.

Examples

For the following example, assume that splineObj points to the spline shown in the example of the vlax-curve-getDistAtParam function.

Obtain the start parameter of the curve:

_$ (setq startSpline (vlax-curve-getStartParam
splineObj))

0.0

Obtain the end parameter of the curve:

_$ (setq endSpline (vlax-curve-getEndParam
splineObj))

17.1546

Determine the first derivative at the parameter midway along the curve:

_$ (vlax-curve-getFirstDeriv
splineObj 

         ( / (- endspline startspline)
2))
    

(0.422631 -1.0951 0.0)