Path: chuka.playstation.co.uk!news From: "SCEE" Newsgroups: scee.yaroze.programming.3d_graphics Subject: Re: reducing polygon overlap Date: Thu, 19 Mar 1998 08:41:04 -0000 Organization: PlayStation Net Yaroze (SCEE) Lines: 28 Message-ID: <6eqlbv$l5r12@chuka.playstation.co.uk> References: <3509c082.5799539@news.playstation.co.uk> <350FF465.7528@127.0.0.1> NNTP-Posting-Host: 194.203.13.10 X-Newsreader: Microsoft Outlook Express 4.71.1712.3 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 Hi, OT clearing blocks the processor, but is very fast ( 1 cycle per OT entry ) Colin. Toby Sargeant wrote in message ... >On Wed, 18 Mar 1998 16:20:53 +0000, Majik wrote: >>which, you could of course do this using two separate OT's but I don't >>think >>clearing the OT has that much of a performance hit. >> >>Majik. > >I'd imagine that clearing the OT is done via DMA. if that's true, and >GsClearOT doesn't wait for it to finish, and you can have more than one >DMA channel active at once, and you're using the dcache, you can probably >get a lot of speedup by having one OT being drawn, while the other is >cleared, at the same time as you're performing calculations for the next >frame. > >it's really this kind of information that would be useful. not exactly >hardware usage, but at least a reasonably detailed description of _how_ >the hardware works, so that we can use it effectively. > >toby.