On Sun, 2010-05-02 at 02:36 -0700, Dave Airlie wrote: > On Sun, May 2, 2010 at 7:30 PM, Jose Fonseca <jfons...@vmware.com> wrote: > > I read the extension and it is not crystal clear, but it seems to imply the > > swizzles are orthogonal to the format, and applied as the very last step > > before being used in a shader. That is, the semantics are the same of > > adding a swizzle instruction after a TEX opcode, regardless of the format. > > At least this is my interpretation of > > > > The values of the texture parameters TEXTURE_SWIZZLE_R_EXT, > > TEXTURE_SWIZZLE_G_EXT, TEXTURE_SWIZZLE_B_EXT, and > > TEXTURE_SWIZZLE_A_EXT, are applied after the swizzling described > > in Table 3.20 (p. 186). The swizzle parameter > > TEXTURE_SWIZZLE_R_EXT affects the first component of Cs as: > > > > BGRA extension does not specify additions to the 3.20 table though (it's > > against spec 1.1) so this is why the guess work. > > > > So my expectaction is that swizzling a BGRA with a .rgba swizzle will get > > bgra. > > > > It is also interesting the mention that the swizzle happens after texture > > compare mode.
Actually, I mistyped, it is not texture compare mode, just depth texture mode. > That is my interpretation as well, so in the r300 hw for example we > use the texture swizzle to implement bgra vs rgba formats, I'd need to > combine that with the incoming GL swizzle from the extension, but I'd > really like to have some sort of test case to demonstrate it as I'm > really not sure how ugly the combine swizzles function might end up. > But it looks as if I need to write a direct to gallium test case to > make sure I'm actually using things, mesa seems to block my attempts, > though maybe with something like a PBO I can make mesa do it. I see now. It's probably worth to fix Mesa to memcpy user data unmodified as much as possible. grepping for GL_BGRA and PIPE_FORMAT_B8G8R8A8 in mesa shows some inconsistencies. Even for PBOs we say that PIPE_FORMAT_B8G8R8A8 is GL_RGBA and not GL_BGRA. A good way to go about this is centralize Gallium <-> GL and Gallium <-> Mesa format information in a big table. It means whenever a new format is added, there are a few places to modify. Anwyay this cleanup is not urgent, and is likely to cause regressions. Jose _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
