[Mesa-dev] mesa clear rework

[Dave Airlie]

Hi,

So I was looking at EXT_texture_integer and realised our clear code was
a bit rough wrt allowing drivers access to the native ints. Also the
use of ClearColor vs ClearColorUnclamped meant that gallium never got the
i/ui clear values at all (even as floats). These patches are my first attempt
at cleaning up the clear code to allow a union + type to be passed around.

They don't fix the gallium interface yet, it still floats the clear colors,
but it does try to push the problem down from the mesa core as much as possible.

Open questions:
1) can we drop the unclamped ClearColor and push the clamping into the paths
that need it? (some drivers + the get.c).

2) can we drop the dd.h ClearColor hook for integer supporting drivers? The
only drivers using this hook are radeon/r200 dri, the x11 and window gdi drivers. If we state that its not necessary for the integer paths it makes the code
a lot saner from what I can see.

Dave.