Re: frame-locking pipes and channels

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Aaron Hightower (aaron++at++qbert.dseg.ti.com)
Tue, 19 Jul 1994 09:06:02 -0500 (CDT)


--- from Drew Hess
>
> I want to frame-lock multiple hardware pipes so that the pfPipes associated with
> each hardware pipe swap buffers synchronously. From the man page for pfPipe:
>
>
> If you wish to frame lock multiple pfPipes so that each pfPipe swaps its
                                 ^^^^^^^^^^^^^^^^
NOTE: pfPipes, not pfChannels

> color buffers at the same time, then you should create a channel group
                                                                ^^^^^^^^^^^^^
So even though you are controlling it via a channel group, it still only
affects the pfPipe associated with that pfChannel.

> consisting of one or more pfChannels on each pfPipe and make sure
> PFCHAN_SWAPBUFFERS is shared.
>
> Example 1: How to frame lock pfPipes
>
> leftChan = pfNewChan(pfGetPipe(0));
> rightChan = pfNewChan(pfGetPipe(1));
>
> /* BPFCHAN_SWAPBUFFERS is shared by default */
> pfAttachChan(leftChan, rightChan);
>
> /* Pipe 0 and pipe 1 are now frame-locked */
>
> What if I modify the code fragment above to look like this:
>
> leftChan1 = pfNewChan(pfGetPipe(0));
> rightChan1 = pfNewChan(pfGetPipe(1));
> leftChan2 = pfNewChan(pfGetPipe(0));
> rightChan2 = pfNewChan(pfGetPipe(1));
>
> pfAttachChan(leftChan1, rightChan1);
>
>
> Since leftChan2 and rightChan2 are running on pipe 0 and pipe 1, respectively,
> and since those pipes are frame-locked, does this mean that leftChan2 and
> rightChan2 will also swap buffers at the same time as leftChan1 and rightChan1,
> even though they're not part of the channel group that is sharing the
> PFCHAN_SWAPBUFFERS attribute?

Yes

> Thanks
> -dwh-
> dhess++at++vision.arc.nasa.gov

Hope this helps,
  Aaron Hightower
  aaron++at++dseg.ti.com


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