Fastest way to find world -> screen mapping

[Tim Monks,,]

To unask the question: I want to draw an object of fixed
screen dimensions at (x,y,z) in world coodinates. I can't
see how to use matrix ops. to do this.
--
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