<SOLVED> How to plot a sphere as wireframe with back view hidden, in R? - r

Question

Using R, I would like to plot a sphere with latitude and longitude lines, but without any visibility of hidden part of the sphere. And, ideally, I'd like to have the initial view start out with a specific tilt (but that's down the road).
This matlab question gets to the idea
Plotting a wireframe sphere in Python hidding backward meridians and parallels
... but it's matlab. The closest solution that stackoverflow suggested
Plot Sphere with custom gridlines in R
doesn't help with the hidden line aspect.
The closest I got was editting a sphereplot routine:
library(sphereplot)
matt.rgl.sphgrid <- function (radius = 1, col.long = "red", col.lat = "blue", deggap = 15,
longtype = "H", add = FALSE, radaxis = TRUE, radlab = "Radius")
{
if (add == F) {
open3d(userMatrix = rotationMatrix((90)*pi/180, 1, 0, 0)) #changed
}
for (lat in seq(-90, 90, by = deggap)) {
if (lat == 0) {
col.grid = "grey50"
}
else {
col.grid = "grey"
}
#create an array here using the sph2car call below, then rotate those and
#set the appropriate ones to NA before passing that array to this call
#ditto for the next plot3d call as well
plot3d(sph2car(long = seq(0, 360, len = 100), lat = lat,
radius = radius, deg = T),
col = col.grid, add = T,
type = "l")
}
for (long in seq(0, 360 - deggap, by = deggap)) {
if (long == 0) {
col.grid = "grey50"
}
else {
col.grid = "grey"
}
plot3d(sph2car(long = long, lat = seq(-90, 90, len = 100),
radius = radius, deg = T),
col = col.grid, add = T,
type = "l")
}
if (longtype == "H") {
scale = 15
}
if (longtype == "D") {
scale = 1
}
# rgl.sphtext(long = 0, lat = seq(-90, 90, by = deggap), radius = radius,
# text = seq(-90, 90, by = deggap), deg = TRUE, col = col.lat)
# rgl.sphtext(long = seq(0, 360 - deggap, by = deggap), lat = 0,
# radius = radius, text = seq(0, 360 - deggap, by = deggap)/scale,
# deg = TRUE, col = col.long)
}
matt.rgl.sphgrid(radaxis=FALSE)
But I can't figure out how to hide the lines.
Any pointers or examples I've overlooked?
SOLUTION: Just prior to the plot3d calls, set any negative values in "y" (in this case, given a first rotation of 90 degrees) to NA