On 12/04/2014, 11:19 AM, Roland Rau wrote:
Dear all,I am using package rgl and I want to change the position where I "stand". Maybe a small example might clarify what I am looking for: # Begininng of explanatory example library(rgl) data(volcano) # the example ?rgl.surface 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[ y-ylim[1]+1 ] rgl.open() rgl.surface(x, z, y, color=col, back="lines") ## now I have the nice volcano surface ## with rgl.viewpoint I can change the elevation ## and the angle from where I look at the rgl.surface # example of ?rgl.viewpoint start <- proc.time()[3] while ((i <- 36*(proc.time()[3]-start)) < 360) { rgl.viewpoint(i,i/4); } # End of explanatory example What I am looking for (in this example) would be a way for me to "stand" on the crater of the volcano, looking in a specific direction. Is there something like a function where I can specify my coordinates (x,y,z) and angle and a zoom factor?
I think you could hack something like that (see the description in ?par3d of how rendering is accomplished), but there's currently no support for it, and it wouldn't be easy, as currently P and M in that description are read-only quantities computed indirectly. So you'd have to essentially trick rgl into producing the P matrix corresponding to the viewing position you want.
I am currently working on some changes that might make this easier, but they likely aren't going to be released for several months.
Duncan Murdoch ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
