Keith Whitwell wrote: > Michel Dänzer wrote: > >>On Thu, 2006-09-21 at 16:29 +0100, Keith Whitwell wrote:> > OK, that's kooky. >> I guess I haven't got a handle on the problem yet for > bigEndian, it may be >>that there's another conversion needed on the back end. >>It could also be that there's now a mismatch between this code and >>thedriver... > > > There should be no net change as a result of this work, so there > shouldn't be any need to change the driver. That's how it's worked on > littleEndian, anyway. > > I found one obvious bug which I'll commit, but I'm thinking I'll have to > disable this path on bigEndian until someone can explain to me: > > 1) How bigEndian affects how we interpret source data relative to its > format and type.
Tables 3.9-3.11 of the GL spec show how the components in a packed type are layed out. That should be unambiguous. > 2) How bigEndian affects how we layout hardware texture formats. > > It doesn't help that the mesa texture format structs don't really > specify the format -- they give a few details but they don't tie the > structure down so it means you have to peer into the implementations of > the fetch and store functions, or guess from the name to figure out what > it really means. The comments/table in texformat.h shows how components are layed out assuming that texels are treated as words (i.e. a 32-bit texel has 4 components). Do we need more than that? > Hence you end up with things like "rgb" and "rgb888" having apparently > different component ordering, for instance. In that particular case, 'rgb888' always has 8-bit components packed in a particular order while the 'rgb' format may have 8, 16 or 32-bit components depending on how Mesa's compiled. Furthermore, the non-packed formats like MESA_TEXFORMAT_RGB and MESA_TEXFORMAT_LUMINANCE_ALPHA are never treated as packed types but as arrays of components. -Brian ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
