Inputting a fixed colour input vector with RGL in R

Question

Is there any way to input a fixed vector of colours to any 3D rgl plots? If so it would be possible to extrude a map tile to a 3D surface based on a raster of the same area. But I'm finding the surface3d function behaves the same as raster::plot by insisting on mapping the input colour vector to the z variable. Is this beyond rgl's functionality at present?

Answer 1

I don't actually know if what you say about the coloring is correct for all rgl coloring functions, but it is not correct for rgl.surface(). This is a corruption of the example on the ?rgl.surface page. The color vector index was formed from the x-y (actually x-z) coordinates and gives a striping effect because they were modulo-ized to pull values from from a limited range.

library(rgl)
data(volcano)

y <- 2 * volcano        

x <- 10 * (1:nrow(y))   
z <- 10 * (1:ncol(y))   

ylim <- range(y)
ylen <- ylim[2] - ylim[1] + 1

colorlut <- terrain.colors(ylen) 

col <- colorlut[(x+length(x)*y +1)%%ylen ] 

rgl.open()
rgl.surface(x, z, y, color=col, back="lines")
rgl.snapshot("striped_volcano.png")