lattice: wireframe "eats up" points; how to make points on wireframe visible?

On Thu, Mar 31, 2011 at 3:26 AM, Marius Hofert <m_hofert at web.de> wrote:

Dear Deepayan,

thanks for answering. It's never too late to be useful.

I see your point in the minimal example. I checked the z-axis limits in my
original problem for the point to be inside and it wasn't there. I can't easily
reproduce it from the minimal example though. I'll get back to you if I run into
this problem again.

In the example below, both points are shown. Although one lies clearly below/under
the surface, it looks as if it lies above. One would probably have to plot this
point first so that the wire frame is above the point. But still, this is
misleading since the eye believes that the wireframe is *not* transparent. This
happens because the lines connecting (0,1,0)--(1,1,0)--(1,0,0) [dashed ones] are
not completely visible [also not the one from (1,1,0) to (1,1,1)]. How can I make
them visible even if they lie behind/under the wireframe? I tried to work with
col="transparent" and with alpha=... but neither did work as I expected.
My goal is to make the small "rectangles" between the wire transparent.
I also use these plots in posters with a certain gradient-like background color
and so it's a bit annoying that the "rectangles" are filled with white color.

Yes, that probably needs a new argument; the default computation is a
bit of a hack. You can try the following workaround for now:

wireframe(z~x*y, pts=pts, aspect=1, scales=list(col=1, arrows=FALSE),
         zlim=c(0,1),
         par.settings = list(background = list(col = "#ffffff11")), ## <- NEW
         panel.3d.wireframe = function(x,y,z,xlim,ylim,zlim,xlim.scaled,
                                       ylim.scaled,zlim.scaled,pts,...){
             panel.3dwire(x=x, y=y, z=z, xlim=xlim, ylim=ylim, zlim=zlim,
                          xlim.scaled=xlim.scaled, ylim.scaled=ylim.scaled,
                          zlim.scaled=zlim.scaled, ...)
             panel.3dscatter(x=pts[,1], y=pts[,2], z=pts[,3],
                             xlim=xlim, ylim=ylim, zlim=zlim,
                             xlim.scaled=xlim.scaled, ylim.scaled=ylim.scaled,
                             zlim.scaled=zlim.scaled, type="p", col=c(2,3),
                             cex=1.8, pch=c(3,4), .scale=TRUE, ...)
         })

col = "#ffffff00" instead will give you full transparency (but
"transparent" will not work), and col = "#ffffff77" will be less
transparent and so on.

-Deepayan