[Rd] Sweave support added to rgl package

[Duncan Murdoch]

I have just committed some code to the rgl package on 
https://r-forge.r-project.org/projects/rgl/ to allow rgl images to be 
inserted into Sweave documents.  (This is not in the CRAN version yet.)  
It makes use of the custom graphics driver support added by Brian Ripley.

In R-devel (which will become R 2.14.0 next spring in New Zealand, next 
fall in most other places), usage is quite straightforward.  For
example, code like this in a Sweave document:

<<fig=true, grdevice=rgl.Sweave, pdf=false, stayopen=TRUE>>=
x <- rnorm(100); y <- rnorm(100); z <- rnorm(100)
plot3d(x, y, z)
@

will insert a .png snapshot of the figure.  Because that chunk has 
"stayopen=TRUE", it can be followed by another chunk to add
to the figure, e.g.

<<fig=true, grdevice=rgl.Sweave, pdf=false>>=
lines3d(x[1:10], y[1:10], z[1:10], col="red")
@

All of this is possible in R 2.13.0, but it takes more work:  see the 
?rgl.Sweave help page.

I will eventually add postscript and PDF output options as well, and 
perhaps some support for the LaTeX movie15 package, but those are not 
there yet.  Comments or bug reports are welcome.

Duncan Murdoch