From: jcnpc!jcn@cis.ohio-state.edu (James C. Nugen)
Subject: Re: TECH: Using TI340x0
Date: Wed, 08 Apr 1992 01:55:02 GMT
Organization: Homebrew Virtual Reality Labs


(montefus@hp1.sm.dsi.unimi.it) writes: 
> I have just one question: if the i860 is SO good in rendering, why does
> ProVision use, for the graphic boards, the i860 (for 3D trasformations) and
> a Toshiba HSP Polygon Processor for the Gouraud rendering?

Because the Toshiba Gouraud Shading Processor (GSP) is much faster at
rendering polygons than the i860.  A single GSP can do 8M Gouraud-shaded
pixels/sec.  You can use four GSP's in parallel to get 32Mpixels/sec.
However, the GSP does have a problem!  Because the GSP only has two 16-bit
interpolators, one for Z depth and one for intensity, it is necessary to
use two GSP's in a special configuration to get RGB.  But as a bonus you
could use 48-bit color! :)

James Nugen
jcn@jcnpc.UUCP