selecting points on 3D scatterplots

Hello Everyone,

I am new to R and need some help.

I have a matrix of x,y,z coordinates that I would like to
interactively plot in 3D and then using the cursor select points on
the plot and have the coordinates sent to a matrix. I am using the rgl
package to plot the data at the moment because it allows me to rotate
and zoom. I also tried cloud and scatterplot3D.

I am looking for a function like 'locator' which is used to select
points on 2D scatterplots.

Thanks in advance!
Abby