Path: chuka.playstation.co.uk!news From: James Russell Newsgroups: scee.yaroze.programming.3d_graphics Subject: Re: 2d sprites in a 3d world Date: Tue, 08 Dec 1998 09:40:01 +0000 Organization: Sony Computer Entertainment Europe Lines: 26 Message-ID: <366CF3F0.7429A66C@scee.sony.co.uk> References: <3659BEF7.663E@mdx.ac.uk> <3659D5B1.41EB5140@scee.sony.co.uk> <366959c3.522585@www.netyaroze-europe.com> <366B9EB5.B8FA3B6C@scee.sony.co.uk> <366c34f0.669519@www.netyaroze-europe.com> NNTP-Posting-Host: mailgate.scee.sony.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.5 [en] (Win95; I) X-Accept-Language: en Robert Swan wrote: > > 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?) OK, here's the REAL answer. By default (a default that you can't change, I might add), all the SZ's are multiplied by 1/16 (1.3.12 fixed point format) before being added to make the 'average'. Why it's 1/16 and not 1/4 I'm not sure. But that means that the answer will always be 14 bits maximum. Which is why you subtract from 14. Hooray for everything. > 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. Ssshh!! No-one is supposed to know about that. :O) Phew, lucky you didn't see the purple machine with 78 on it. -- == James_Russell@scee.sony.co.uk +44 (171) 447-1626 == Developer Support Engineer - Sony Computer Entertainment Europe As unaquainted as a blind man and his shadow.