如何在云中添加平面（3d条形图）

Question

我想知道是否有一种简单的方法可以在我的云端3D条形图中以z = 0添加平面。这样，我就可以在平面上方和下方之间进行分隔（意味着z> 0 vs. z <0）。

除了需要在z = 0处有一个平面外，我已经完成了整个绘图。

dall = as.matrix(data.frame(v1= c(-1.35,1.2,6), v2=c(-1.5,0.5,5), v3= c(-4.2,0.5,11)))
row.names(dall)  = c("R1", "R2",  "R3")

cloud(dall, panel.3d.cloud = panel.3dbars,
      xbase = 0.4, ybase = 0.4, zlim = c(min(dall), max(dall)),
      scales = list(arrows = FALSE, just = "right"), xlab = list('  R values',col='blue',cex=0.75), ylab = list('V values',col='blue',cex=0.75),zlab = list('z',col='blue',cex=0.75),
      main = list("3D Plot",col='blue'),
      col.facet = level.colors(dall, at = do.breaks(range(dall), 50),
                               col.regions = cm.colors,
                               colors = TRUE),
      colorkey = list(col = cm.colors, at = do.breaks(range(dall), 50)),
      screen = list(z = 20, x = -60))