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\name{lighting}
\alias{perspLighting}
\alias{phongLighting}
\title{Lighting Functions}
\description{
Functions to compute colors modified for lighting effects.
}
\usage{
phongLighting(normals, view, light, color, color2, alpha, material = "default")
perspLighting(normals, view, light, color, color2, alpha, material = "default")
}
\arguments{
\item{normals}{numeric matrix with three columns representing surface
normal vectors.}
\item{view}{numeric vector of length 3 representing the direction to
the viewer.}
\item{light}{numeric vector of length 3 or 4. The first three
elements represent the direction to the light. The fourth element,
if present, represents light intensity; the default is 1.}
\item{color}{colors to use for faces in the direction of the normal
vectors.}
\item{color2}{opposite face color.}
\item{alpha}{alpha channel level, a number between 0 and 1.}
\item{material}{material specification. Currently possible values are
the character strings "dull", "shiny", "metal", and "default".} }
\value{
Vector of color specifications.
}
\details{
\code{phongLighting} uses the Phong lighting model to compute colors
modified for view direction, light direction, and material properties.
\code{perspLighting} implements approximately the same lighting model
as the \code{persp} function.
}
}
\keyword{hplot}
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