transparent surface in rgl

On 10/5/2005 11:10 AM, Prof Brian Ripley wrote:

On Wed, 5 Oct 2005, Duncan Murdoch wrote:

On 10/5/2005 9:31 AM, Prof. Paul R. Fisher wrote:

Hi all
I am a complete newbie to this list (just subscribed) and a newcomer to
R (an S user from olden times). I have been using scatter3d to create a
3d scatter plot with surface. The graphic is created within the rgl
package and I have used rgl.postscript to export it so I can generate a
publication quality image. My problem is that the plotted surface is no
longer transparent in the postscript output ie. the rgl.spheres that are
behind the surface disappear in the postscript image. Can't seem to find
any info on this anywhere. Am I doing something wrong? Is there an easy fix?

I think Postscript doesn't support transparency (or at least the version
of Postscript that the rgl.postcript function targets doesn't support
it).  You may have to export a bitmapped format using the rgl.snapshot()
function.  If your original window is very large this may give you good
enough quality.

Common PostScript (level 2) does not support either full or partial 
transparency (and I guess partial transparency is meant here or the 
surface could just not be plotted).  It would be good to have a rgl.pdf 
which did.  These days PDF is the `portable PostScript' and since version 
1.4 has had alpha-channel supoort.

Ref:

http://en.wikipedia.org/wiki/Transparent_pixels#Transparency_in_PostScript

The library we use (GL2PS) apparently supports PDF output, and that's 
one of the format options for rgl.postscript(), so maybe we already do 
support that.  I haven't tried it.