| Re: [AD] [WIN] pageflip needs fixing before 4.0 |
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----- Original Message -----
From: "Eric Botcazou" <ebotcazou@xxxxxxxxxx>
To: "Allegro conductors" <conductors@xxxxxxxxxx>
Sent: Wednesday, October 31, 2001 4:23 PM
Subject: Re: [AD] [WIN] pageflip needs fixing before 4.0
> To Robin: Argh !!! You're going to frighten everyone with your title ;-)
Doesn't frighten me :p
>
> > Some gfx drivers have problems with the current windows bodge of
> > allocating 3 video pages that causes pageflip to flicker. This is fixed
> > by only allocating 2 buffers, which is currently not possible as it is
> > unknown if the programme will use triple buffering.
>
> More detailed informations: the problem seems to originate in 3.9.35 WIP
but
> surfaced only recently. Moreover I think it's a little untimely to say
that
> it is only fixed by allocating 2 buffers: afaik all the proposed fixes
have
> not been tested yet and we have already a first workaround. I'm relatively
> confident that we'll find a fix.
OK, I accept that, but we do have a report this worked. I have another
suggestion:
I notice from your wddbmp.c (not posted on this list) you removed
Enumeration, how about seeing if (int EnumSurfacesCallback) assigning the
two pages the other way round helps (tripbuffer first)?
> > I am posting this here for thoughts on the best solution:
>
> Only for post 5.0 if we follow Peter's original versioning.
>
> > 1) Do nothing, and update the docs to explain this problem and that
> > programmes should always offer triple buffer (which always works) too.
>
> Not very nice.
I quite like this, no reason not to support triple buffer if you are using
pageflip....
> > 2) Add a var or set_video_pages (int numpages); function (like
> > set_color_depth) to be called before set_gfx_mode.
>
> Too much Windows specific.
Surely other ports need this info?
> > 3) Use a scheme like the older allegro virtualpage pageflip:
> > set_gfx_mode (GFX_AUTODETECT, 640, 480, 0, 0);
>
> Maybe the way to go: extending the syntax of set_gfx_mode() to pass some
> hints about the number of video pages.
Yes, this is ok.
> > 4) Allocate 2 pages (1 backbuffer) so pageflip works on call to
> > set_gfx_mode, then release DD and re-init DD with 2 backbuffers if it
> > turns out a 2nd is needed for triple buffer
>
> Worse than a nightmare ;-)
I think this is not as bad as you are making it sound ;)
Another thought:
If a game uses pageflip only, we can supply a DLL (somewhere) that only
allocs 1bb.
Or.... Pester the gfx driver people about it.