[R] rgl and rglwidget: Weird behaviour than animating lines

[Duncan Murdoch]

On 23/06/2016 5:59 AM, Nicole Karakin wrote:
> I am trying to follow help and Internet examples to create a very
> simple animation of a 3d-line in R. This is just a test and my final
> goal is to use this functionality to visually verify results of some
> geometrical transformations on 3d-movement data that I am analysing.
> So basically I need nothing more than a ‘3d-player’ interface that
> allows for usual interaction (rotation, zoom, play, stop, slide).
>
> I figured out that rgl package does the job and I am able to use it
> for the sphere/points animation. But now I need to use it on lines and
> I get very strange results. In the example below there are 4 points
> and two lines (cyan and red) that connect the same points but the red
> line is for some reason in the ‘wrong’ place. The animation doesn’t
> make sense neither. Now, I am thinking may be it is impossible to do
> >> to animate more than one vertex with more than one attribute? But I
> don’t see this in documentation and obviously it is possible because
> line is animated! I spent quite a long time trying to figure out what
> is going on and will appreciate any help/advise/directions on how i
> can 'fix' this behaviour.
> thanks, Nicole
>
> Ps: the code below is a chunk in the markdown file and I am using Rstudio
>
> #-----------------------------------------
> require(rgl)
> require(rglwidget)
> p11=c(0,0,0)
> p21=c(50,50,0)
> p12=c(50,0,0)
> p22=c(10,50,50)
>
> saveopts <- options(rgl.useNULL = TRUE)
> did=list()
> did[[1]]=plot3d(rbind(p11,p21,p12,p22), type="s", alpha = 1, lwd = 5,
> col = c('brown','darkgreen','orange','green'))
> did[[2]]=spheres3d(c(100,100,100), alpha = 1, lwd = 5, col = "blue",radius=2)
> did[[3]]=lines3d(rbind(p11,p21),lwd=8, col='cyan',alpha=.9)
> did[[4]]=planes3d(0, 0, 1, 0, alpha=.4, col='green')
> did[[5]]=lines3d(rbind(p11,p21),lwd=2, col='red')
> aspect3d(1, 1, 1)
> did[[6]]=grid3d(c("x-", "z-"),at = NULL,col = "gray",lwd = .5,lty = 1,n = 5)
> sceneT = rglwidget(elementId = "plot3dT",width=500, height=300) #%>%
> rgl.ids()
> rgl.attrib(id=did[[3]],attrib = c(1:length(did[[3]])))
>
> playwidget(sceneT,list(
>    vertexControl(values = rbind(c(0,0,0,0,0,0),c(50,50,50,50,50,50)),
>               vertices = 1:6, attributes = "z", objid = did[[4]], param
> = 1:2,interp =T),
>    vertexControl(values = r1,
>               vertices = 1:2, attributes = c('x',"y","z",'x',"y","z"),
> objid = did[[5]], param = 1:2,interp =T)),
>    start = 1, stop = 2, step = .1, precision = 3)
> options(saveopts)

You can run rglwidget-using scripts in RStudio (or other front ends) and 
they'll generally work more or less the same as they do in a Markdown 
document.  However, when I try to do that with this one, it fails, 
because you use r1 without defining it.
You might want to think about deleting everything unnecessary as well:  
if you want to illustrate problems with lines, just show lines.

You should also say what versions of rgl and rglwidget you're using; the 
ones on R-forge are quite a bit newer than the ones on CRAN.

Duncan Murdoch