We often neglect to get too involved in the discussion of what options people should always enable when they play games. Rather, we tend to focus on what we test with. Honestly, our recommended settings for playing the games we test would be very similar to the settings we use to benchmark with one very important exception: we would enable triple buffering (which implies vsync) whenever possible. While it's not an available option in all games, it really needs to be, and we are here to make the case for why gamers should use triple buffering and why developers need to support it.
Most often gamers, when it comes to anything regarding vsync, swear by forcing vsync off in the driver or disabling it in the game. In fact, this is what we do when benchmarking because it allows us to see more clearly what is going on under the hood. Those who do enable vsync typically do so to avoid the visual "tearing" that can occur in some cases despite the negative side effects.
We would like to try something a little different with this article. We'll include two polls, one here and one at the end of the article. This first poll is designed to report what our readers already do with respect to vsync and double versus triple buffering.
{poll 134:300}
After reading the rest of this article, our readers are invited to answer a related poll which is designed to determine if arming gamers with the information this article provides will have any impact on what settings are used from here on out.
First up will be a conceptual review of what double buffering and vsync are, then we'll talk about what triple buffering brings to the table. For those who really want the nitty gritty (or who need more convincing) we will provide follow that up with a deeper dive into each approach complete with some nifty diagrams.
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Schmide - Friday, June 26, 2009 - link
My conceptions.Triple Buffering is 2 back buffers that alternate a copying (BLT) to a front buffer(primary/screen) while the other is rendering.
Double Buffering is two surfaces that trade places between front and back buffer by switching states. Only works in full screen mode.
Back Buffering where one surface is rendered to then copied to the front buffer(primary/screen). Often falsely called Double Buffering.
Triple Buffering is designed to avoid the surface lock during a copy to the front buffer (BLT) in windowed mode so the next rendering cycle can start early. In full screen mode it just adds an extra step (BLT) in the rendering cycle, since a hardware is swap moves no memory just pointers.
I would imagine the only reason a Triple Buffer would reduce tearing is, on average the back buffer copy is playing catchup to the primary surface update and the chances of half rendered frames is a bit less.
So proper use would be
Double Buffer - Full Screen Rendering.
Back Buffer - Simple Full/Windowed Rendering
Triple Buffer - Complex Windowed Rendering.
Schmide - Friday, June 26, 2009 - link
PrinceGaz explained it so I understand below.Schmide - Friday, June 26, 2009 - link
-"is"I want to add. Vsinc can be a problem because of the synchronous nature between game code and rendered frames. The more frames you get the better your character moves. If you lock down/cap your frames you may be loosing some response.
Example. In cod4 crash, the wall by the dumpster near the 3 story building, you can only jump over it if your frames get above 125. I assume there is some round off error and Euler like calculations going on.
The ideal rendering cycle, other than a fixed or capped game play engine, would be: vsinc, update, render a frame, do game code without rendering over and over, repeat.
DerekWilson - Friday, June 26, 2009 - link
triple buffering does not use a blit to move a back buffer to a front buffer -- it is still done with buffer renaming.i.e. you'll have three pointers: one to the frame currently being rendered, one to the most recently completed frame (these are both back buffers), and one to the front buffer.
after a vertical refresh completes, if there is not a more recently completed frame than the current front buffer, the current front buffer locks again and the same frame is drawn. If there is a more recently completed frame newer than the one that was just drawn, then this buffer becomes the front buffer and the old front buffer becomes the other back buffer.
when the GPU finishes rendering into one back buffer, it marks that buffer as the most recently completed and swaps the pointers so that it's current buffer was the previous most recently completed buffer that is not the front buffer.
...
i know, clear as much right?
but really, there is no blit involved in a sane triple buffering implementation.
nvmarino - Friday, June 26, 2009 - link
Hey Derek, thanks for the article. Any chance you could provide more detail about the issues with SLI and triple buffering? Such as why it's an issue, can the issues be overcome by game developers or is it an issue at the driver level, and also what are the typical problems an end-user would experience?Compddd - Friday, June 26, 2009 - link
Or can I turn Vsync off and just leave triple buffering on? Like in L4D or TF2 for instance?DerekWilson - Friday, June 26, 2009 - link
it is not possible to run triple buffering without vsync.the purpose of triple buffering is to provide a buffer that can remain locked during the vertical redraw (so that there is no corruption); this IS vsync.
but the advantage is that there are still two buffers left over so that you can always save the most recently completed frame while working on the next one (and also not corrupting what is currently being displayed).
think of it like this: there is one current work space, one most recently completed frame, and one vsync'd buffer.
Compddd - Friday, June 26, 2009 - link
Why do these games like L4D and TF2 have the option to turn off Vync or Triple bufferng then? Or turn them both on, or turn one on and leave the other one off?JonP382 - Saturday, June 27, 2009 - link
They don't. There's an option to turn on vsync with double buffering, or vsync with triple buffering. Or no vsync.Atechie - Friday, June 26, 2009 - link
Thanks for showning me why still keeping my 2x21"CRT's are a good choice, so I don't get less IQ, fake black, tearing suckt 60Hz refresh and all the other crap that make LCD's less than steller for gaming.