Does DirectX implement Triple Buffering?
- by Asik
As AnandTech put it best in this 2009 article:
In render ahead, frames cannot be dropped. This means that when the
queue is full, what is displayed can have a lot more lag. Microsoft
doesn't implement triple buffering in DirectX, they implement render
ahead (from 0 to 8 frames with 3 being the default).
The major difference in the technique we've described here is the
ability to drop frames when they are outdated. Render ahead forces
older frames to be displayed. Queues can help smoothness and
stuttering as a few really quick frames followed by a slow frame end
up being evened out and spread over more frames. But the price you pay
is in lag (the more frames in the queue, the longer it takes to empty
the queue and the older the frames are that are displayed).
As I understand it, DirectX "Swap Chain" is merely a render ahead queue, i.e. buffers cannot be dropped; the longer the chain, the greater the input latency. At the same time, I find it hard to believe that the most widely used graphics API would not implement such fundamental functionality correctly. Is there a way to get proper triple buffered vertical synchronisation in DirectX?
