compareBezierArcLength: Returns difference between input length and a Bezier arc...

In bezier: Toolkit for Bezier Curves and Splines

Description

This function calls bezierArcLength and returns the absolute difference between the Bezier curve or spline arc length and an input length. The primary use of this function is to supply optim with a single value for identifying a parametric value at a particular arc length in pointsOnBezier.

Usage

compareBezierArcLength(p, l, t1 = 0, t2 = NULL, deg = NULL, 
                       relative.min.slope = 1e-6, absolute.min.slope = 0)

Arguments

p	control points, input either as vector, matrix or list (see bezier).
l	the length against which the arc length is compared.
t1	an initial parametric value for a Bezier curve or spline.
t2	a final parametric value for a Bezier curve or spline.
deg	a numeric indicating the degree (or order) of a Bezier spline. For Bezier curves, the degree is computed automatically based on the number of control points.
relative.min.slope	a numeric indicating at which change in arc length relative to the instaneous length estimated length is considered sufficiently close to the actual length.
absolute.min.slope	a numeric indicating at which absolute change in arc length estimated length is considered sufficiently close to the actual length.

Details

The performance of this function is identical to bezierArcLength except that fewer input parameters are available. See "Details" in bezierArcLength.

Value

the absolute difference between the input length l and the Bezier arc length.

Author(s)

Aaron Olsen

See Also

bezier, pointsOnBezier, bezierArcLength

Examples

## BEZIER CURVE ARC LENGTH COMPARISON ##
## BEZIER CURVE CONTROL POINTS
p <- matrix(c(0,0, 1,4, 2,2), nrow=3, ncol=2, byrow=TRUE)

## COMPARE THE BEZIER ARC LENGTH TO ZERO
## SIMPLY RETURNS ARC LENGTH
compareBezierArcLength(p=p, l=0)

## COMPARE THE BEZIER ARC LENGTH TO ONE
compareBezierArcLength(p=p, l=1)

## SPECIFYING DIFFERENT T PARAMETERS
compareBezierArcLength(p=p, l=1, t1=0.3, t2=0.8)


## BEZIER SPLINE ARC LENGTH COMPARISON ##
## BEZIER SPLINE CONTROL POINTS
p <- matrix(c(0,0, 1,4, 2,2, 3,0, 4,4), nrow=5, ncol=2, byrow=TRUE)

## COMPARE THE BEZIER ARC LENGTH TO ZERO
## SIMPLY RETURNS ARC LENGTH
compareBezierArcLength(p=p, l=0, deg=2)

Example output

[1] 4.083686
[1] 3.083686
[1] 0.4338598
[1] 8.167371

bezier documentation built on May 1, 2019, 9:46 p.m.