x3p_add_legend: Display legend in active rgl object
In x3ptools: Tools for Working with 3D Surface Measurements

Display the legend for colors and annotations in the active rgl window. In case no rgl window is opened, a new window displaying the x3p file (using default sizes and zoom) opens.

1	x3p_add_legend(x3p, colors = NULL)

`x3p`	x3p object with a mask
`colors`	named character vector of colors (in hex format by default), names contain annotations

x3p <- x3p_read(system.file("sample-land.x3p", package="x3ptools"))
## Not run: 
# run when rgl can open window on the device
x3p_image(x3p) 
x3p_add_legend(x3p) # add legend

## End(Not run)