These functions allow rgl graphics to be embedded in knitr
documents, either as bitmaps (hook_rgl with format "png"),
fixed vector graphics (hook_rgl with format "eps", "pdf" or
"postscript"), or interactive WebGL graphics (hook_webgl).
setupKnitr()
hook_rgl(before, options, envir)
hook_webgl(before, options, envir)Standard knitr hook function arguments.
A string to be embedded into the output, or NULL if called
when no output is available.
The setupKnitr() function needs to be called once
at the start of the document to install the knitr hooks
and to initialize hook_webgl.
The following chunk options are supported:
rgl.keepopen:  no longer used.  Ignored
  with a warning.
rgl.newwindow (default FALSE):  Whether to open a new window for the display.
rgl.margin (default 100):  number of pixels by which to indent the
  WebGL window.
dpi, fig.retina, fig.width, fig.height:  standard knitr chunk
  options used to set the size of the output.
dev:  used by hook_rgl to set 
  the output format.  May be "eps", "postscript",
  "pdf" or "png" (default:  "png").
rgl.Sweave embeds fixed images in Sweave documents.