Re: [x11drv] d3d stencil support

[Adam D. Moss]

Hi!

Oliver Stieber wrote:
> - if (visual == NULL) {
> -
>    /* fallback to a 1 bit stencil (opengl states that at least 1 bit of stencil must be provided for on of the available configurations) */
> -
>    WARN("Failed to get a visual with at least 8 bits of stencil\n");
> -
>    int dblBuf2[] = {GLX_RGBA,GLX_DEPTH_SIZE,16,GLX_STENCIL_SIZE,1,GLX_DOUBLEBUFFER,None};
> -
> -
>    wine_tsx11_lock();
> -
>    visual = pglXChooseVisual(display, DefaultScreen(display), dblBuf2);
> -
>    wine_tsx11_unlock();
> -
>    if (visual == NULL) {
> -
>        /* This should only happen if we cannot fidn a match with a depth size 16 */
> -
>        FIXME("Failed to find a suitable visual\n");
> -
>    }
> - }

It's always nice to have a fallback, but in real life I've
never seen PC hardware (even back to the 90s) which supports
a 1-bit stencil buffer and not a 8-bit stencil buffer, so
this may be over-redundant.  (Would be interested in hearing
of any consumer hardware which only does a 1-bit stencil.)

Regards,
--adam

[x11drv] d3d stencil support

[Oliver Stieber]

--- "Adam D. Moss"  wrote:
> Hi!
>
> Oliver Stieber wrote:
> > - if (visual == NULL) {
> > -
> >    /* fallback to a 1 bit stencil (opengl
>
> states that at least 1 bit of stencil must be
> provided for on of the available configurations) */
> > -
> >    WARN("Failed to get a visual with at
>
> least 8 bits of stencil\n");
> > -
> >    int dblBuf2[] =

{GLX_RGBA,GLX_DEPTH_SIZE,16,GLX_STENCIL_SIZE,1,GLX_DOUBLEBUFFER,None};
> > -
> > -
> >    wine_tsx11_lock();
> > -
> >    visual = pglXChooseVisual(display,
>
> DefaultScreen(display), dblBuf2);
> > -
> >    wine_tsx11_unlock();
> > -
> >    if (visual == NULL) {
> > -
> >        /* This should only happen if we
>
> cannot fidn a match with a depth size 16 */
> > -
> >        FIXME("Failed to find a suitable
>
> visual\n");
> > -
> >    }
> > - }
>
> It's always nice to have a fallback, but in real
> life I've
> never seen PC hardware (even back to the 90s) which
> supports
> a 1-bit stencil buffer and not a 8-bit stencil
> buffer, so
> this may be over-redundant.  (Would be interested in
> hearing
> of any consumer hardware which only does a 1-bit
> stencil.)

The fallback is there because 1 bit stencil is the
minimum required by the opengl specification, so it is
possible that somewhere there is a driver that only
supports 1 bit stencil.

Oliver.
> Regards,
> --adam

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[x11drv] d3d stencil support

[Adam D. Moss]

Oliver Stieber wrote:
> The fallback is there because 1 bit stencil is the
> minimum required by the opengl specification, so it is
> possible that somewhere there is a driver that only
> supports 1 bit stencil.

I understood that, I was simply saying that I don't think
there's ever been a consumer graphics card that did only
1-7 bits -- they seem to universally do 0 or 8 bits of
stencil (even the software-renderers), so the fallback is
likely a waste of breath, though I appreciate caution.

Perhaps more to the point, does D3D only guarantee a
1-bit stencil buffer?  A 1-bit stencil buffer (most
especially one without GL_EXT_stencil_wrap) is of very,
very limited use.  I somewhat expect that no D3D applications
(except maybe, just maybe, some very simple test-apps)
will actually operate correctly with a 1-bit unwrapped
stencil.

Cheers,
--adam

[x11drv] d3d stencil support

[Oliver Stieber]

--- "Adam D. Moss"  wrote:
> Oliver Stieber wrote:
> > The fallback is there because 1 bit stencil is the
> > minimum required by the opengl specification, so
>
> it is
> > possible that somewhere there is a driver that
>
> only
> > supports 1 bit stencil.
>
> I understood that, I was simply saying that I don't
> think
> there's ever been a consumer graphics card that did
> only
> 1-7 bits -- they seem to universally do 0 or 8 bits
> of
> stencil (even the software-renderers), so the
> fallback is
> likely a waste of breath, though I appreciate
> caution.
>
> Perhaps more to the point, does D3D only guarantee a
> 1-bit stencil buffer?  A 1-bit stencil buffer (most
> especially one without GL_EXT_stencil_wrap) is of
> very,
> very limited use.  I somewhat expect that no D3D
> applications
> (except maybe, just maybe, some very simple
> test-apps)
> will actually operate correctly with a 1-bit
> unwrapped
> stencil.

I haven't come across any yet, but I've mainly been
concentrating on d3d9. there's a good chance that some
older applications may use a 1bit stencil to speed
things up. applications that would generally be
regarded as 2d can make use of a 1bit stencil buffer
for masks and screen wipes.

e.g. http://www.mvps.org/directx/articles/wipe/
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/directx9_c/...

I wouldn't expect someone with hardware that doesn't
support 8bit+ stencils to be playing the latest games,
but there's potential for them to be using other
applications that require a simple stencil buffer, or
simple 3D an no stencil at all, in which case they
require some kind of fallback.
> Cheers,
> --adam

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[x11drv] d3d stencil support

[Jakob Eriksson]

Adam D. Moss wrote:
> Hi!
>
> Oliver Stieber wrote:
> > - if (visual == NULL) {
> > -
> >    /* fallback to a 1 bit stencil (opengl states that at least 
> >
> > 1 bit of stencil must be provided for on of the available 
> > configurations) */
> > -
> >    WARN("Failed to get a visual with at least 8 bits of 
> >
> > stencil\n");
> > -
> >    int dblBuf2[] = 
> >
> > {GLX_RGBA,GLX_DEPTH_SIZE,16,GLX_STENCIL_SIZE,1,GLX_DOUBLEBUFFER,None};
> > -
> > -
> >    wine_tsx11_lock();
> > -
> >    visual = pglXChooseVisual(display, DefaultScreen(display), 
> >
> > dblBuf2);
> > -
> >    wine_tsx11_unlock();
> > -
> >    if (visual == NULL) {
> > -
> >        /* This should only happen if we cannot fidn a match 
> >
> > with a depth size 16 */
> > -
> >        FIXME("Failed to find a suitable visual\n");
> > -
> >    }
> > - }
>
> It's always nice to have a fallback, but in real life I've
> never seen PC hardware (even back to the 90s) which supports
> a 1-bit stencil buffer and not a 8-bit stencil buffer, so
> this may be over-redundant.  (Would be interested in hearing
> of any consumer hardware which only does a 1-bit stencil.)

Sun ELC. Not exactly consumer hardware though.

regards,
Jakob