Path: chuka.playstation.co.uk!news From: Craig Graham Newsgroups: scee.yaroze.freetalk.english Subject: Re: Triangles, Quads??? Date: Tue, 13 Oct 1998 08:19:48 +0100 Organization: PlayStation Net Yaroze (SCEE) Lines: 36 Message-ID: <3622FF14.B0A6AA9D@hinge.mistral.co.uk> References: <362238AE.DF3414FF@usa.net> <36228105.D38787F2@datasys.net> NNTP-Posting-Host: d3-s41-197-telehouse.mistral.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.05 [en] (Win95; I) Darco wrote: > The playstation intreprets a quad as 2 triangles. (I know this is true > because I've got the numbering wrong on a quad many times, and the GPU > renders 2 distinct triangles) Look at this rough sketch. (If it doesn't > look right, look at it with a fixed size font) > > 0------1 > | /| > | / | > | / | > | / | > | / | > |/ | > 2------3 > > Because it does this, it really doesn't matter which you choose. If > there is a speed difference it will be minimal. However, the data for 2 > triangles is larger than 1 quad. So if you are dealing with large > models, it may be more efficient to use quads rather than triangles. A quad should be faster than 2 triangles because the gte only has to do 4vertex transformations instead of 6 (2 of the vertices are common between the two triangles). It's the same reason that mesh lists are faster on Direct3D (less calculations per polygon). NOTE: The GPU is much faster than the gte. You can render more triangles than you can calculate, so any reduction in calculation is a benefit. > 'Darco Craig.