# gplot3d.arrow: Add Arrows a Three-Dimensional Plot

## Description

`gplot3d.arrow`

draws an arrow between two pairs of points.

## Usage

gplot3d.arrow(a, b, radius, color = "white", alpha = 1)

## Arguments

a

a vector or three-column matrix containing origin X,Y,Z coordinates.

b

a vector or three-column matrix containing origin X,Y,Z coordinates.

radius

the arrow radius, in current plotting units. May be a vector, if multiple arrows are to be drawn.

color

the arrow color. May be a vector, if multiple arrows are being drawn.

alpha

alpha (transparency) value(s) for arrows. (May be a vector.)

## Details

`gplot3d.arrow`

draws one or more three-dimensional "arrows" from the points given in `a`

to those given in `b`

. Note that the "arrows" are really cones, narrowing in the direction of the destination point.