Just wanted to thank you for reminding me about 'backface culling' -- at CEGEP (what they call college in Quebec) back in 75/76 we had access to an HP 9810 Programmable Calculator, and one of the geeks managed to do 3D plots of cos(x)/exp(x^2) -- with backface culling (although I never knew what it was called until now).

That was an absolutely fascinating tool -- one day, I decided to plot sin(x) on the x axis and cos(x) on the y axis to see what kind of wacky curve I'd get. Of course, it started drawing a unit circle. D'Oh.