title: plotting label names onto 3D plot generated by plot3d (rgl)
body: <p>I would like to plot results from a MDS analysis with 3 dimensions using <code>plot3d()</code> (<strong>rgl</strong>). Data and code look like this:</p>
  
  <pre><code>   threedim$points
                [,1]        [,2]      [,3]        [,4]
     Dutch      -6.45931417  -2.1589222 -5.829244  -0.4891066
     German     -7.27770201   0.2666916 -2.198595   6.8658602
     Albanian    4.11799731   0.6810336 11.356935  -2.2623921
     Armenian   13.58431670  21.6527626 -2.245146   6.3506665
     French     -0.24170759  -0.8579159 14.197611  -0.1871443
  
     threedim$points[,1] -&gt; x
     threedim$points[,2] -&gt; y
     threedim$points[,3] -&gt; z
     library(rgl)
     plot3d(x,y,z)
     text(c("Dutch","German","Albanian","Armenian","French"))
  </code></pre>
  
  <p>I get the following error message: </p>
  
  <blockquote>
    <p>"Warning message:
    In xy.coords(x, y, recycle = TRUE) : NAs introduced by coercion"</p>
  </blockquote>
  
  <p>What am I doing wrong?</p>