[Mesa-dev] r300g + mesa/st support for EXT_texture_swizzle

[Roland Scheidegger]

On 27.04.2010 13:13, Dave Airlie wrote:
> Another trying to figure out gallium patch from me,
> 
> This is in theory EXT_texture_swizzle support, r300g passes the glean
> test with this now.
> 
> Some caveats in the patch (i.e. I'm not sure what exactly is correct
> state tracker behaviour wrt sampler views).

Dave,

Basically looks good but I have some concerns. First, I think the
extension should not be announced unconditionally but rather based on a
cap bit. There's hw we care about which can't do this (i965, svga) and
it seems unreasonable to expect them to do workarounds just so this
extension can be always exposed.
Also, I think it won't work correctly if the pipe format itself has a
swizzle (which is different to rgba). There are really two swizzles
here, one coming from the extension the other inherited from the format,
and they need to be combined. Either in the driver or the state tracker,
 I think it's underspecified right now but I think the swizzle parameter
should express the hardware view, hence the combining should take place
in the state tracker. (Also, for depth textures it should also take the
depth texture mode into account, but that might be out of the scope of
what you're trying to do.)

Roland