[R] Simplex Density Plots

[Graham Neubig]

Hello,

I have just started using R, and have found it quite easy to make
plots of probability densities for normal and beta distributions, etc.

Now, I'm looking at trying to make a simplex plot of a Dirichlet
density, but have gotten stuck and was hoping that someone could help.
Ideally, the plot would look something like the 3d plots on Wikipedia here:
http://en.wikipedia.org/wiki/File:Dirichlet_distributions.png

Although if these are impossible, a color-coded 2d simplex would work as well.

Does anyone have an idea or link about how to make simplex plots?

Thanks in advance,
Graham