Path: chuka.playstation.co.uk!news From: James Russell Newsgroups: scee.yaroze.programming.2d_graphics Subject: Re: Active Buffer Question Please Respond Date: Thu, 22 Jan 1998 12:59:27 +1300 Organization: Peace Computers NZ Ltd Lines: 21 Message-ID: <34C68BDF.167E@peace.co.nz> References: <34C35011.7F79BE6D@infores.com> <01bd25bd$a6cf6be0$6c0b0a0a@newcastle.twowaytv.co.uk> NNTP-Posting-Host: intro.peace.co.nz Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 3.0Gold (X11; I; IRIX 6.2 IP22) One of the things that's different from traditional PC/Amiga graphics programming is that although you are double buffering, what your program is calculating is **2** frames behind instead of 1. As Craig pointed out, you draw on one buffer while displaying the other (the essence of double buffering), but what is confusing is that you're program isn't the one doing the drawing. It's the GPU. If you are displaying frame X in Buffer 1, then the GPU is busy drawing frame X+1 in Buffer 2, and your program is busy sorting polygons and fiddling around with ordering tables for frame X+2. This puzzled me for a while when I was trying to pause on a frame and it would only appear after I'd done GsSwapDispBuff() twice instead of once. -- ==PEACE COMPUTERS ==James.Russell@peace.co.nz - 64(9)3730400 -Fax 64(9)3730401 Cthulhu saves. In case he gets hungry later.