Can one use polygon() or equivalent in lattice and ggplot2 plots?

Question

Is it possible to annotate lattice (or ggplot2) figures with elements created with polygon() (or elements created with a similar function) from the graphics library?

I'm not too familiar with either library beyond examples of simple graphs posted on the web and printed in Deepayan Sarkar's book. Therefore, while I have code for what I've been doing in R with the graphics library, pointing me to relevant, equivalent functions and usage examples for lattice or ggplot2 specifically would be appreciated. Thanks.

Answer 1

Here is the ggplot2 version of the first example in ?polygon()

x <- c(1:9,8:1)
y <- c(1,2*(5:3),2,-1,17,9,8,2:9)

ggplot(NULL, aes(1:10, 1:10)) + geom_point() +
  geom_polygon(aes(x, y), fill = "orange", colour = "skyblue", alpha = 0.5)