title: R statistics: Drawing multiple plots in RGL
body: <p>Does anyone know how to draw multiple 3d plots in one picture using RGL in R Statistics.  </p>
  
  <p>I have three variables and each of those variables belong to two groups.  I want each group to have a different color so I can visualize it.  In regular R stats, I just use subset and then use par(new=T).  I haven't seen anything equivalent for the 3d plot.  Does anyone have any suggestion?</p>
  
  <p>Thanks!</p>