[R] rgl zooming to an arbitrary location

[Gareth Davies]

I have been using rgl to view xyz point clouds containing topographic 
data ( with around 10^5 - 10^6 points).

It's working well aside from one thing: I would like to be able to zoom 
into an arbitrary part of the plot. However so far I could only figure 
out how to zoom into the centre.

See the example below -- in this case, I cannot 'zoom-in' to anything 
other than the central hill in the topography, whereas I would like to 
be able to zoom to an arbitrary location.

Is there a way to get around this?

##########################################
# EXAMPLE CODE
##########################################
library(rgl)
# Make up some topography
x=runif(1e+06, min=0,max=1000)
y=runif(1e+06, min=0,max=1000)
# Elevation with 'hill' in the centre
z=sin(x/50.)+cos(y/50.) + 30*exp(-((x-500)^2+(y-500)^2)*0.001)
plot3d(x,y,z,col=z+3,aspect=FALSE)
# Now try zooming [right mouse button]. I can only zoom into the central 
hill, not elsewhere.


Below are the details of my R Install

 > sessionInfo()
R version 3.1.1 (2014-07-10)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
  [1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_AU.UTF-8        LC_COLLATE=en_AU.UTF-8
  [5] LC_MONETARY=en_AU.UTF-8    LC_MESSAGES=en_AU.UTF-8
  [7] LC_PAPER=en_AU.UTF-8       LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods base

other attached packages:
  [1] rgl_0.93.1098        unstructInterp_0.0-1 rgeos_0.3-6
  [4] rgdal_0.8-16         sp_1.0-15            geometry_0.3-4
  [7] magic_1.5-6          abind_1.4-0          SearchTrees_0.5.2
[10] roxygen2_4.0.1

loaded via a namespace (and not attached):
[1] digest_0.6.4    grid_3.1.1      lattice_0.20-29 Rcpp_0.11.2
[5] stringr_0.6.2   tools_3.1.1
 >