bspline (version 2.3.0)

bcurve: nD B-curve governed by (x,y,...) control points.

Description

nD B-curve governed by (x,y,...) control points.

Usage

bcurve(xy, n = 3)

Value

Function of one argument calculating B-curve. The argument is supposed to be in [0, 1] interval.

Arguments

xy

Real matrix of (x,y,...) coordinates, one control point per row.

n

Integer scalar, polynomial order of B-spline (3 by default)

Details

The curve will pass by the first and the last points in 'xy'. The tangents at the first and last points will coincide with the first and last segments of control points. Example of signature is inspired from this blog.

Examples

  # simulate doctor's signature ;)
  set.seed(71);
  xy=matrix(rnorm(16), ncol=2)
  tp=seq(0,1,len=301)
  doc_signtr=bcurve(xy)
  plot(doc_signtr(tp), t="l", xaxt='n',  yaxt='n', ann=FALSE, frame.plot=FALSE,
      xlim=range(xy[,1]), ylim=range(xy[,2]))
  # see where control points are
  text(xy, labels=seq(nrow(xy)), col=rgb(0, 0, 0, 0.25))
  # join them by segments
  lines(bcurve(xy, n=1)(tp), col=rgb(0, 0, 1, 0.25))
  
  # randomly curved wire in 3D space
if (FALSE) {
  if (requireNamespace("rgl", quietly=TRUE)) {
     xyz=matrix(rnorm(24),ncol=3)
     tp=seq(0,1,len=201)
     curv3d=bcurve(xyz)
     rgl::plot3d(curv3d(tp), t="l", decorate=FALSE)
  }
}