persp.
perspp(x, y, z, from.persp)
persp function.
x and
y representing the projection of the input coordinates onto 2-dimensional coordinates that match the current perspective plot.
The
perspp function uses information returned by
persp; hence
perspp can be invoked only after a call to
persp, while the graphics device containing the perspective plot is still open.
# perspective plot from the default viewpoint zout <- persp(switzerland) # plot and label a high-elevation point points(perspp(11, 12 , switzerland[11,12], zout)) text(perspp(11, 12, switzerland[11,12], zout), "High Point", adj = 0)