[R] add points to 3D plot using p3d {onion}

[Bradley Christoffersen]

Hi,

Can anyone guide me as to how I can add points to a p3d() plot from
the onion package?  I want to plot points with different colors on the
same 3D plot.  Perhaps I can do this without adding points but somehow
directing the 'h' parameter to give different color to points based on
a factor I assign to them?

FYI, I can do this using using scatterplot3d() and points3d(), but
these plots lack perspective and hence it is hard to sense depth
without the use of color.

Thanks,
Brad