Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!apple!uokmax!munnari.oz.au!bruce!merlin!tim
From: tim@resmel.bhp.com.au (Tim Monks)
Newsgroups: comp.sys.sgi
Subject: Fastest way to find world -> screen mapping
Keywords: transform world coords screen coords matrix inversion
Message-ID: <1991Jun4.031535.18607@resmel.bhp.com.au>
Date: 4 Jun 91 03:15:35 GMT
Sender: usenet@resmel.bhp.com.au (USEnet nntp account)
Organization: BHP Research - Melbourne Laboratories, AUSTRALIA
Lines: 25

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@resmel.bhp.com.au