basis3d: Draw Basis Vectors in an rgl Scene

Description

The function calculates and optionally draws basis vectors to be used as coordinate axes in an rgl 3D display. For geometric diagrams and some data displays, this can be more useful than using axis3d or box3d to provide guides or axes. The origin argument permits multiple diagrams or graphs in the same display, each with their own coordinate axes.

Usage

basis3d(
  matrix = diag(3),
  origin = c(0, 0, 0),
  scale = 1,
  draw = TRUE,
  label = draw,
  texts = colnames(basis),
  lwd = 3,
  cex = 2,
  ...
)

Value

Returns invisibly a 6 x 3 matrix, whose columns are the coordinate axes, c("x", "y", "z"). Odd numbered rows give the coordinates of the origin, while even numbered rows give the locations of the tips of the vectors.

Arguments

matrix: A 3 x 3 matrix, whose columns are the basis vectors, typically of unit length.
origin: Origin in the rgl scene of the basis vectors
scale: Scaling factor for the basis vectors
draw: If TRUE, the vectors are plotted
label: If TRUE, the vectors are labeled at their tips
texts: A character vector of length 3 used for labels. Defaults to c("x", "y", "z").
lwd: Line width for vectors
cex: Character size for labels
...: Other arguments, passed to segments3d and text3d

Author

Michael Friendly

Examples

Run this code


# show two different sets of basis vectors
open3d()
basis3d()
A <- matrix(c(1,2,0.1,
              2,1,0.1,
              0.1,0.1,0.5), 3,3)
basis3d(t(A), col="red")

# scene with two different displays
open3d()
basis3d()
basis3d(origin=c(2,0,0))