Can't share sampler varients across multiple tex units because the texture
pointer is in the sampler varient. That prevents different textures per unit.
Fixes progs/demos/multiarb, progs/glsl/samplers, etc.
Split into component pieces, stitch together at runtime using function
pointers. Make it possible to utilize the existing fastpaths as image-level
filters for generic mip-filtering routines.
Remove special case for rectangle filtering, as it can now be handled by
the 2d path.
As most of the mesa demo texturing was already covered by fast paths, its
harder to find examples of speedups, but tunnel gets a boost as mip-nearest
filtering is now able to access the img_2d_linear_wrap_POT functions
for sampling within a mipmap level.
Let eg. sp_get_samples_rect be hooked directly in as the tgsi sampler
routine.
Add a field to determine whether this is a vertex or fragment sampling
call, and massage parameters to match the tgsi call.
Fixes two issues - firstly for mipmap levels with one or more
dimensions smaller than tilesize, the code was sampling off the edge
of the texture (but still within the tile).
Secondly, in the linear_mipmap_linear case, both the default code and
new fastpath were incorrect. This change fixes the fastpath and adds
a comment to the default path, which still needs to be fixed.
Basically the issue is that the coordinates in the smaller texture
level are/were being computed by just dividing thecoordinates from the
larger texture level by two, as in:
x0[j] /= 2;
y0[j] /= 2;
x1[j] /= 2;
y1[j] /= 2;
The issues with this are signficant. Initially x1 is most often equal
to x0+1, but after this, it will likely be equal to x0, so we will not
actually be performing the linear blend within the smaller mipmap.
The fastpath code avoided this (recalculated x1), but was still using
the weighting factors from the larger mipmap level (xw, yw), which
were incorrect.
Change the fastpath code to do two full, independent linear samples of
the two mipmap levels before blending. The default code needs to do
the same thing.
linear-mip-linear-repeat-POT sampling faspath, provides a very nice
speedup to apps that do this common type of texturing.
Test case: demos/terrain, turn fog off, turn texturing on.
Without patch: 12 fps
With patch: 20 fps.
Because this is interpolated (ie. early) depth, we can build in an
assumption about the quads emitted by triangle setup, ie that they
are actually linear spans. Interpolate z over those spans in z16
format to save on math & conversion.
