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\name{arrow3d}
\alias{arrow3d}
\title{
Draw an arrow
}
\description{
Draws various types of arrows in a scene.
}
\usage{
arrow3d(p0 = c(1, 1, 1), p1 = c(0, 0, 0),
barblen, s = 1/3, theta = pi/12,
type = c("extrusion", "lines", "flat", "rotation"),
n = 3, width = 1/3, thickness = 0.618 * width,
spriteOrigin = NULL,
plot = TRUE, ...)
}
\arguments{
\item{p0}{
The base of the arrow.
}
\item{p1}{
The head of the arrow.
}
\item{barblen}{
The length of the barbs (in display coordinates).
Default given by \code{s}.
}
\item{s}{
The length of the barbs as a fraction of line length. Ignored if \code{barblen} is present.
}
\item{theta}{
Opening angle of barbs
}
\item{type}{
Type of arrow to draw. Choose one from the list
of defaults. Can be abbreviated. See below.
}
\item{n}{
Number of barbs.
}
\item{width}{
Width of shaft as fraction of barb width.
}
\item{thickness}{
Thickness of shaft as fraction of barb width.
}
\item{spriteOrigin}{
If arrow is to be replicated as sprites, the origins relative
to which the sprites are drawn.
}
\item{plot}{
If \code{TRUE} (the default), plot the object;
otherwise return the computed data that
would be used to plot it.
}
\item{\dots}{
Material properties passed to \code{\link{polygon3d}}, \code{\link{shade3d}} or \code{\link{segments3d}}.
}
}
\details{
Four types of arrows can be drawn. The shapes
of all of them are affected by \code{p0}, \code{p1}, \code{barblen},
\code{s}, \code{theta}, material properties
in \code{...}, and \code{spriteOrigin}. Other parameters
only affect some of the types, as shown.
\describe{
\item{\code{"extrusion"}}{(default) A 3-dimensional
flat arrow, drawn with \code{\link{shade3d}}. Affected by \code{width}, \code{thickness} and
\code{smooth}.}
\item{\code{"lines"}}{Drawn with lines, similar to \code{\link{arrows}}, drawn with \code{\link{segments3d}}. Affected by \code{n}.}
\item{\code{"flat"}}{A flat arrow, drawn with \code{\link{polygon3d}}. Affected by \code{width} and \code{smooth}.}
\item{\code{"rotation"}}{A solid of rotation,
drawn with \code{\link{shade3d}}. Affected by
\code{n} and \code{width}.}
}
Normally this function draws just one arrow from
\code{p0} to \code{p1}, but
if \code{spriteOrigin} is given (in any form
that \code{\link{xyz.coords}(spriteOrigin)} can
handle), arrows will be drawn for each point
specified, with \code{p0} and \code{p1}
interpreted relative to those origins. The
arrows will be drawn as 3D sprites which will
maintain their orientation as the scene is rotated, so this is a good way to indicate
particular locations of interest in the scene.
}
\value{
If \code{plot = TRUE} (the default), this is
called mainly for the side effect of drawing
the arrow; invisibly returns the id(s) of
the objects drawn.
If \code{plot = FALSE}, the data that would be
used in the plot (not including material
properties) is returned.
}
\author{
Design based on \code{heplots::arrow3d}, which contains modifications by Michael Friendly
to a function posted by Barry Rowlingson to R-help on 1/10/2010. Additions by Duncan Murdoch.
}
\examples{
xyz <- matrix(rnorm(300), ncol = 3)
plot3d(xyz)
arrow3d(xyz[1,], xyz[2,], type = "extrusion", col = "red")
arrow3d(xyz[3,], xyz[4,], type = "flat", col = "blue")
arrow3d(xyz[5,], xyz[6,], type = "rotation", col = "green")
arrow3d(xyz[7,], xyz[8,], type = "lines", col = "black")
arrow3d(spriteOrigin = xyz[9:12,], col = "purple")
}
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