On 10/12/15 15:53, Roland Scheidegger wrote:
Am 10.12.2015 um 15:44 schrieb Jose Fonseca:
On 10/12/15 08:09, Dave Airlie wrote:
On 10 December 2015 at 14:31, <srol...@vmware.com> wrote:
From: Roland Scheidegger <srol...@vmware.com>
Discovered this when working on other clip code, apparently didn't work
correctly - the combination of linear interpolated values and using
gl_ClipVertex produced wrong values (failing all such combinations
in piglits glsl-1.30 interpolation tests).
Use the pre-clip-pos values when determining the interpolation factor to
fix this.
Unfortunately I have no idea what I'm doing here really, but it fixes
all
these failures in piglit (all interpolation-noperspective-XXX-vertex, 10
tests in total). Albeit piglit coverage of clipping isn't great, so
hopefully
someone can confirm this actually makes sense, and wouldn't cause
failures
elsewhere...
This makes sense to me, in that interpolating should definitely happen
on pre-clipped coordinates.
The code was added in
http://cgit.freedesktop.org/mesa/mesa/commit/?id=4625a9b1adf7a30c56e2bbeb41573fbba4465851
then revised in
http://cgit.freedesktop.org/mesa/mesa/commit/?id=ab74fee5e1a3fc3323b7238278637b232c2d0d95
and
http://cgit.freedesktop.org/mesa/mesa/commit/?id=5da967aff5adb3e27954488206fb885ea1ede0fd
The 2nd change of Brian seems (if I read correctly) to do precisely the
opposite.
I wonder if "clip" and "pre_clip_pos".
What do you wonder?
Ah, if these things are really what they sounds like.
I'm thinking there could be a mismatch what softpipe and llvmpipe do
here (rather, the llvm vs. non-llvm path). In particular, draw_llvm will
always write to both clip pos and pre-clip-pos, if there wasn't a a
clip_user it will just write the same (look at invocation of store_clip).
Right. The key point here is to check that those tests don't regress
with softpipe.
Jose
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