One further note: It initially looked like the USCALED/SSCALED surface formats might be usable for this, and if so would reduce the required shader workaround to just a single mov for the float to [u]int conversion -- but unfortunately the sampler is broken for these as well.
-- Chris On Mon, Feb 3, 2014 at 10:29 PM, Chris Forbes <chr...@ijw.co.nz> wrote: > This series adds a bunch of workarounds to enable ARB_texture_gather > (in its more restrictive form) on Gen6 hardware. > > These are necessary because Gen6's gather4 instruction doesn't work > correctly with integer or unsigned integer formats. > > The approach is: > > * For 32-bit wide formats, pretend the surface is FLOAT, and reinterpret > the bits as INT/UINT. This requires only a surface format override; nothing > in the shader. > > * For 8- and 16-bit wide formats, pretend the surface is UNORM, > and recover the appropriate unsigned integer value by multiplying up, > and then converting to INT/UINT. If INT is required, then fix the sign > extension of the value by the usual SHL/ASR method. > > This now passes all the applicable ARB_texture_gather piglit tests. > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
