thigmophobe3d: Find the direction away from the closest point in a 3d...
In rgl: 3D Visualization Using OpenGL

Description Usage Arguments Details Value Note Author(s) References See Also Examples

Jim Lemon's thigmophobe function in the plotrix package computes good directions for labels in a 2D plot. This function does the same for a particular projection in a 3D plot by projecting down to 2D and calling his function.

thigmophobe3d(x, y = NULL, z = NULL, 
              P = par3d("projMatrix"), 
              M = par3d("modelMatrix"),
              windowRect = par3d("windowRect"))

`x, y, z`	point coordinates. Any reasonable way of defining the coordinates is acceptable. See the function `xyz.coords` for details.
`P, M, windowRect`	The projection and modelview matrices, and the size and position of the display in pixels.

Since thigmophobe3d projects using fixed P and M, it will not necessarily choose good directions if the user rotates the display or makes any other change to the projection.

A vector of values from 1 to 4 to be used as the pos argument in text3d.

The example below shows how to update the directions during an animation; I find that the moving labels are distracting, and prefer to live with fixed ones.

Duncan Murdoch

plotrix

text3d

if (requireNamespace("plotrix")) {
  # Simulate some data
  xyz <- matrix(rnorm(30), ncol = 3)
  
  # Plot the data first, to establish the projection
  plot3d(xyz)
  
  # Now thigmophobe3d can choose directions
  textid <- text3d(xyz, texts = 1:10, pos = thigmophobe3d(xyz))
  
  # Update the label positions during an animation
  if (interactive() && !rgl.useNULL()) {
    spin <- spin3d(rpm = 5)
    f <- function(time) {
      par3d(skipRedraw = TRUE)
      on.exit(par3d(skipRedraw = FALSE))
      pop3d(id = textid)
      # Need to rotate before thigmophobe3d is called
      result <- spin(time)
      par3d(userMatrix = result$userMatrix)
      textid <<- text3d(xyz, texts = 1:10, pos = thigmophobe3d(xyz))
      result
    }
    play3d(f, duration = 5)
  } else
    textid   # just print the static display
}