--- "Adam D. Moss" aspirin@ntlworld.com 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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