treevizPDF <- function(x, ..., height = NULL, width = 10, new = FALSE)
{
    if (!new) {
        if (!exists("last_treeviz", envir = .PlotPhyloEnv))
            new <- TRUE
        else
            tf <- get("last_treeviz", envir = .PlotPhyloEnv)$PDFfilename
    }
    if (new) {
        tf <- paste(tempfile(), "pdf", sep = ".")
        assign("last_treeviz", list(PDFfilename = tf),
               envir = .PlotPhyloEnv)
    }

    n <- Ntip(x)
    if (is.null(height)) height <- n * 0.19
    ## 0.19 is strheight("x", "inches") * 1.5
    pdf(tf, height = height, width = width)

    ## to avoid wide empty areas above and below the tree:
    par(yaxs = "i")
    plot.phylo(x, y.lim = c(-1, n + 1), ...)

    dev.off()
    system(paste(options()$pdfviewer, tf), wait = FALSE)
}

treevizGL <- function(x, edge.color = "orange", tip.color = "black")
{
    if (!require(rgl))
        stop("package 'rgl' not installed")

    rgl.segments <- function(x0, y0, x1, y1, z0 = NULL, z1 = NULL) {
        N <- length(x0)
        if (is.null(z0)) z0 <- rep(0, N)
        if (is.null(z1)) z1 <- rep(0, N)
        x <- as.vector(rbind(x0, x1))
        y <- as.vector(rbind(y0, y1))
        z <- as.vector(rbind(z0, z1))
        segments3d(x, y, z, col = edge.color)
    }

    rgl.cladogram.plot <- function(edge, xx, yy) {
        rgl.segments(xx[edge[, 1]], yy[edge[, 1]],
                     xx[edge[, 2]], yy[edge[, 2]])
        rgl.texts(xx[1:n], yy[1:n], rep(0, n), x$tip.label,
                  adj = 0, col = tip.color)
    }

    n <- length(x$tip.label)
    m <- Nnode(x)
    N <- Nedge(x)

    yy <- numeric(n + m)
    TIPS <- x$edge[x$edge[, 2] <= n, 2]
    yy[TIPS] <- 1:n

    x <- reorder(x, order = "pruningwise")
    ans <- .C("node_height_clado", as.integer(n),
              as.integer(m), as.integer(x$edge[, 1]),
              as.integer(x$edge[, 2]), as.integer(N),
              double(n + m), as.double(yy),
              DUP = FALSE, PACKAGE = "ape")
    xx <- ans[[6]] - 1
    yy <- ans[[7]]

    rgl.open()
    rgl.cladogram.plot(x$edge, xx, yy)
}