Colouring a 3D plot according to z-values

Here is a script that colors a 3D plot according to the z value (height) of each point.

persp.withcol <- function(x,y,z,pal,nb.col,...,xlg=TRUE,ylg=TRUE)
{
	colnames(z) <- y
	rownames(z) <- x

	nrz <- nrow(z)
	ncz <- ncol(z) 

	color <- pal(nb.col)
	zfacet <- z[-1, -1] + z[-1, -ncz] + z[-nrz, -1] + z[-nrz, -ncz]
	facetcol <- cut(zfacet, nb.col)
	par(xlog=xlg,ylog=ylg)
	persp(
		as.numeric(rownames(z)),
		as.numeric(colnames(z)),
		as.matrix(z),
		col=color[facetcol],
		...
		)
}

dd