This function checks the
"rgl.useNULL" option if present, or the
RGL_USE_NULL environment variable if it is not. If the value is
TRUE or a string which matches “yes” or “true”
in a case-insensitive test,
TRUE is returned.
This function is checked by the initialization code when the rgl package
is loaded. Thus if you want to run RGL on a system where there is no
graphics support, you should run
options(rgl.useNULL = TRUE)
or set the environment variable
library(rgl) (or other code that
loads rgl), and it will not fail in its attempt at initialization.
A logical value indicating the current default for use of the null device.
rgl.useNULL() #>  TRUE