[R] plotting planes and lines in wireframe()

[wwsprague@ucdavis.edu]

Hi R-helpers

I would like to plot some planes which are perpendicular to the x-y 
plane, such as x=y.  Is there a way to do this in wireframe?  I realize 
that I am not plotting a function of x, y since there are infinite 
number of z's that satisfy the above relation....  Hmm...

Somewhat related, I would also like to plot a line in 3 d space...

Finally, if you are feeling really brave, I am interested in doing all 
of this based on sums generating vectors (I know there is a linear 
algebra term for this) -- ie generate the plane based on c_1*v_1 + 
c_2*v_2 for c_1 and c_2 in reals.

Thanks again to all you helpful folks!
W