title: why scatterplot3js overlays plots when input dataset is changed?
body: <p>I'm trying to use scatterplot3js and give it different datasets given by the user. However, if I change the dataset, it tries to plot them together. I tried to change the renderer (renderer='webgl') it does not work.</p>
  
  <pre><code>library(threejs)
  library(shiny)
  get.dt &lt;- function(x) switch(x, rock = rock, mtcars = mtcars)
  app &lt;- shinyApp(
       ui = bootstrapPage(
         selectInput("data", "dataset", c("rock", "mtcars") ),
         scatterplotThreeOutput('plot')
       ),
       server = function(input, output) {
         output$plot &lt;- renderScatterplotThree({ 
         data &lt;- get.dt(input$data)
         scatterplot3js(as.matrix(data[,1:3]))
    })
       }
     )
     runApp(app)
   }
  </code></pre>