srol...@vmware.com writes: > From: Roland Scheidegger <srol...@vmware.com> > > The existing fbo-blending-formats test is mostly useless for anything but > unorm formats, since it does not test any values outside [0,1] (neither for > src, dst, intermeidate calculations, blend result). > I tried to enhance it but it got too complex, in particular because I really > want to test snorm, not floats (which aren't really validated much neither), > because if you actually use int math for them it's difficult to handle and > llvmpipe had lots of bugs. And it's not even obvious from the GL spec when > clamping actually happens (in particular, the inverse blend factors will be > in range [0,2]). snorm blending is sort of semi-supported in GL, the > presence of EXT_texture_snorm doesn't guarantee it (and nvidia doesn't support > the extension, presumably because they can't or don't want to deal with the > legacy alpha/luminance/intensity formats), and while GL 3.1 introduces the > snorm formats too it isn't guaranteed for rendering neither (for GLES OTOH > there's a EXT_render_snorm extension), so the format handling of the > fbo-blending-formats test isn't really sufficient and not easily extensible. > So, this test will test actual blend behavior with values which will need > clamping, and where the intermediate and final values will be negative (and, > for the inverse blend factors, be even larger than one). > This passes (now) on llvmpipe, and nvidia blob. softpipe is a complete > failure (if there's clamping it will always clamp to [0,1] for starters), > and as a matter of fact, softpipe doesn't get the clamping right even with > unorm neither, since values outside [0,1] won't get clamped in the tile > cache when there's no clamping, hence they'll enter the blend later when > blend is enabled unclamped - but there's no test for this (note this is > only an issue if the fragment color clamp is disabled).
I thought the ARB_color_buffer_float/render test was trying to cover this.
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