This document describes how to embed rgl
scenes in HTML documents and use embedded Javascript to control a WebGL display in an HTML document. For more general information about rgl
, see rgl Overview.
We assume that the HTML document is produced from R markdown source using knitr
or rmarkdown
. This format mixes text with Markdown markup with chunks of R code. There is a limited amount of discussion of other methods.
There are two ways to embed an rgl
scene in the document. The recommended one is to call rglwidget
to produce a “widget” which can be embedded into your document by printing it.
The older method is described in the Legacy WebGL Methods document. It is likely to be supported for some time, but is not recommended for new projects, as the widget method is easier for me to maintain.
I have conducted experiments on a third method. This is intended to be similar to the way standard 2D graphics are included by knitr
, i.e. it will detect the fact that you’ve drawn something, and just include it automatically. At present it is not recommended, but that may change in the future.
Most browsers now support WebGL, but in some browsers it may be disabled by default. See http://get.webgl.org for help on a number of different browsers.
We start with a simple plot of the iris data. We insert a code chunk and call the rglwidget
function with optional argument elementId
. This allows later Javascript code to refer to the image. We also save the object ids from the plot, so that they can be manipulated later.
library(rgl)
plotids <- with(iris, plot3d(Sepal.Length, Sepal.Width, Petal.Length,
type="s", col=as.numeric(Species)))
rglwidget(elementId = "plot3drgl")
Next we insert a button to toggle the display of the data.
toggleWidget(sceneId = "plot3drgl", ids = plotids["data"], label = "Data")
The sceneId
is the same as the elementId
we used in rglwidget()
, the ids
are the object ids of the objects that we’d like to toggle, and the label
is the label shown on the button. To find the names in the plotids
variable, apply names()
or unclass()
:
names(plotids)
## [1] "data" "axes" "xlab" "ylab" "zlab"
unclass(plotids)
## data axes xlab ylab zlab
## 7 8 9 10 11
magrittr
pipesIt can be error-prone to set the elementId
in the rglwidget()
to match the sceneId
in the toggleWidget()
(or playwidget()
, described below). In the usual case where both are intended to appear together, magrittr
-style pipes can be used quite flexibly: the first argument of the control widget accepts the result of rglwidget()
(or other control widgets), and the controllers
argument of rglwidget()
accepts control widgets. For example,
rglwidget() %>%
toggleWidget(ids = plotids["data"], label = "Data")
You can swap the order of button and scene; use the magrittr
dot to pass the toggleWidget
to rglwidget
in the controllers
argument:
toggleWidget(NA, ids = plotids["data"], label = "Data") %>%
rglwidget(controllers = .)
We have seen how to change the contents of the plot using toggleWidget
. We can do more elaborate displays. For example, we can redo the previous plot, but with the three species as separate “spheres” objects and buttons to toggle them:
clear3d() # Remove the earlier display
setosa <- with(subset(iris, Species == "setosa"),
spheres3d(Sepal.Length, Sepal.Width, Petal.Length,
col=as.numeric(Species),
radius = 0.211))
versicolor <- with(subset(iris, Species == "versicolor"),
spheres3d(Sepal.Length, Sepal.Width, Petal.Length,