3D plots of dotprops objects using rgl package

```
# S3 method for dotprops
plot3d(
x,
scalevecs = 1,
alpharange = NULL,
color = "black",
PlotPoints = FALSE,
PlotVectors = TRUE,
UseAlpha = FALSE,
...,
gridlines = FALSE,
plotengine = getOption("nat.plotengine")
)
```

## Arguments

- x
A dotprops object

- scalevecs
Factor by which to scale unit vectors (numeric, default:
1.0)

- alpharange
Restrict plotting to points with `alpha`

values in
this range to plot (default: null => all points). See
`dotprops`

for definition of `alpha`

.

- color
Character or numeric vector specifying colours for
points/vectors. See details.

- PlotPoints, PlotVectors
Whether to plot points and/or tangent vectors
(logical, default: tangent vectors only)

- UseAlpha
Whether to scale tangent vector length by the value of
`alpha`

- ...
Additional arguments passed to `points3d`

and/or
`segments3d`

- gridlines
Whether to display gridlines when using plotly as the backend plotting
engine (default: `FALSE`

)

- plotengine
the plotting backend engine to use either 'rgl' or
'plotly'.

## Value

invisible list of results of rgl plotting commands

## Details

Tangent vectors are plotted by `segments3d`

and centred on the
relevant point. Points are plotted by `points3d`

.

`color`

will be recycled by `points3d`

and `segments3d`

.
However in the special case that `color`

has length equal to the
number of points in `x`

, then it will be duplicated before being
passed to `segments3d`

so that the result is that each vector is
coloured uniformly according to `color`

(since segments3d expects 2
colours for each line segment, blending them if they are different).