vectors3d: Draw 3D vectors

In matlib: Matrix Functions for Teaching and Learning Linear Algebra and Multivariate Statistics

Draw 3D vectors

Description

This function draws vectors in a 3D plot, in a way that facilitates constructing vector diagrams. It allows vectors to be specified as rows of a matrix, and can draw labels on the vectors.

Usage

vectors3d(
  X,
  origin = c(0, 0, 0),
  headlength = 0.035,
  ref.length = NULL,
  radius = 1/60,
  labels = TRUE,
  cex.lab = 1.2,
  adj.lab = 0.5,
  frac.lab = 1.1,
  draw = TRUE,
  ...
)

Arguments

X	a vector or three-column matrix representing a set of geometric vectors; if a matrix, one vector is drawn for each row
origin	the origin from which they are drawn, a vector of length 3.
headlength	the headlength argument passed to arrows3d determining the length of arrow heads
ref.length	vector length to be used in scaling arrow heads so that they are all the same size; if NULL the longest vector is used to scale the arrow heads
radius	radius of the base of the arrow heads
labels	a logical or a character vector of labels for the vectors. If TRUE and X is a matrix, labels are taken from rownames(X). If FALSE or NULL, no labels are drawn.
cex.lab	character expansion applied to vector labels. May be a number or numeric vector corresponding to the the rows of X, recycled as necessary.
adj.lab	label position relative to the label point as in text3d, recycled as necessary.
frac.lab	location of label point, as a fraction of the distance between origin and X, recycled as necessary. Values frac.lab > 1 locate the label beyond the end of the vector.
draw	if TRUE (the default), draw the vector(s).
...	other arguments passed on to graphics functions.

Value

invisibly returns the vector ref.length used to scale arrow heads

Bugs

At present, the color (color=) argument is not handled as expected when more than one vector is to be drawn.

Author(s)

Michael Friendly

See Also

arrows3d, texts3d, rgl.material

Other vector diagrams: Proj(), arc(), arrows3d(), circle3d(), corner(), plot.regvec3d(), pointOnLine(), regvec3d(), vectors()

Examples

vec <- rbind(diag(3), c(1,1,1))
rownames(vec) <- c("X", "Y", "Z", "J")
library(rgl)
open3d()
vectors3d(vec, color=c(rep("black",3), "red"), lwd=2)
# draw the XZ plane, whose equation is Y=0
planes3d(0, 0, 1, 0, col="gray", alpha=0.2)
vectors3d(c(1,1,0), col="green", lwd=2)
# show projections of the unit vector J
segments3d(rbind(c(1,1,1), c(1, 1, 0)))
segments3d(rbind(c(0,0,0), c(1, 1, 0)))
segments3d(rbind(c(1,0,0), c(1, 1, 0)))
segments3d(rbind(c(0,1,0), c(1, 1, 0)))
# show some orthogonal vectors
p1 <- c(0,0,0)
p2 <- c(1,1,0)
p3 <- c(1,1,1)
p4 <- c(1,0,0)
corner(p1, p2, p3, col="red")
corner(p1, p4, p2, col="red")
corner(p1, p4, p3, col="blue")

rgl.bringtotop()

matlib documentation built on Oct. 3, 2024, 1:09 a.m.