Path: chuka.playstation.co.uk!news From: "Alex Herbert" Newsgroups: scee.yaroze.programming.2d_graphics Subject: Lost time Date: Fri, 15 Jan 1999 16:30:34 -0000 Organization: PlayStation Net Yaroze (SCEE) Lines: 29 Message-ID: <77nqn4$hoo3@chuka.playstation.co.uk> NNTP-Posting-Host: th-usr01-22.ndirect.co.uk X-Newsreader: Microsoft Outlook Express 4.72.3110.1 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Hi all, I'm puzzled. In the Programming FAQ there is a section headed "How can I get more CPU/GPU time?" and I just don't get it. I don't see why it makes a difference whether VSync(0) waits for the actual VBlank (start of the virtical blanking period) or the top of the frame (end of virtical blank). Surely the time interval between these events will remain at 1/50 second either way. Unless VSync(0) actually waits to see a VBlank AND a top of frame, in which case if VSync(0) is called during the virtical blank it will drop a frame. Conversly I have noticed that in interlaced modes I get significantly less HSyncs before I have to call VSync(0) (without dropping frames) than I do in non-interlaced modes. I'm assuming that the two issues are related. If my assumptions are correct, this would suggest that in interlaced mode there is indeed a some sort of problem with with the GPU during the VBlank, and VSync(0) will block the CPU for the whole of the VBlank period. However, the fact that I get more processing time in non-interlaced modes hints that VSync(0) does work correctly and that writing my own VSync equivalent by utilising VSyncCallback would be of no benefit. This is all guesswork, and I get the feeling I must be a little confused. Can anyone shed some light on this? Herbs