R/makeOmni.R

In jbrzusto/sensorgnome-R-package: Tools for the sensorgnome project.

#' Create an omnidirectional antenna object.
#'
#' Creates a 'proto' object of class 'antenna' which will store
#' position and orientation of an omnidirectional antenna.
#' 
#' @param pos 3-element antenna position vector (x, y, z)
#' 
#' @param axis 3-element antenna orientation axis (x, y, z). This
#' points along the antenna.  See \code{\link{makeAxis}}, for other forms
#' in which you can specify this parameter.
#'
#' @references \url{http://en.wikipedia.org/wiki/Dipole_antenna#Half-wave_dipole}
#'
#' @author John Brzustowski \email{jbrzusto@@REMOVE_THIS_PART_fastmail.fm}

makeOmni = function(pos, axis) {
    if (! exists(".omni.proto"))
        .omni.proto <<- proto(
            gain=function(obj, x) gainOmni(acos(dot(x, obj$axis))),
            
            setAxis = function(obj, axis) {
                ## store axis, ensuring it's a unit vector forming the first column of a 1 x 3 matrix
                obj$axis = matrix(makeAxis(axis), 1, 3)
            },
            
            setPos = function(obj, pos) {
                obj$pos = matrix(pos, ncol=3)
            },
            
            type="omnidirectional")
    
    ## copy prototype
    x = proto(.omni.proto)

    ## store position
    x$setPos(pos)

    ## store axis
    x$setAxis(axis)
    
    ## proto() doesn't copy extra class attributes from its proto argument, so set it here:
    class(x) = c(class(x), "antenna")
    return(x)
}