Path: chuka.playstation.co.uk!news
From: robert_swan@playstation.sony.com (Robert Swan)
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: 2d sprites in a 3d world
Date: Mon, 07 Dec 1998 20:07:36 GMT
Organization: PlayStation Net Yaroze (SCEE)
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On Mon, 07 Dec 1998 09:24:05 +0000, James Russell
<James_Russell@scee.sony.co.uk> wrote:

>The GTE averages the 3/4 vertices of the quad, and uses the average as the offset into the OT (after
>the 14-OT_LENGTH shifting of course). Now to divide by 4, you just shift the 16 bit sum of all the
>vertices by 2 to the right. Which means that the value you've got left would have (as a maximum) bit
>13 set. So that's why you subtract from 14.

so what your saying is that after the perspective transformation, a
vertex' z depth relative to the viewpoint is a 14bit number? (which if
you add four together to find average you need to bit shift an extra
2, hence sorting 3d mofdels you bit shift 16-otable length?)

Rob

no no, I dont mean the green debug machine with 2 written on it, I
meant the blue machine with 3 written on it next to that one. Mind
you, looks nicer than the crappy grey tin box with 24 written on it.