Fastest way to find world -> screen mapping

[Tim Monks]

What is the fastest way of mapping (x,y,z) (world coords) to (sx,sy)
(screen coords) on a SG?

I know about :
  i. Getting the viewing matrix from the pipeline, and inverting this
     matrix on the CPU (and various speedups on the same theme, 
     to make the inversion faster). I don't like the idea of making the
     CPU do a job the pipeline should be doing.

 ii. Going into feedback mode, and getting results back from pipeline.
     Chapter 17 (GL programming guide) says this is a no-no to be avoided.

Are there any better options ?


Thanks in advance,

Tim.

--
Dr Tim Monks                                
Image Processing & Data Analysis Group | (direct)   (+61-3)566-7448
BHP Research - Melbourne Laboratories  | (switch)   (+61-3)560-7066
245 Wellington Rd, Mulgrave, 3170,     | (fax)      (+61-3)561-6709
AUSTRALIA                              | (internet) tim at resmel.bhp.com.au