Created attachment 126029 [details] [revie=
w]
Patch: Handle I915_SEMANTIC_POS when setting texCoords for gl_FragCoord
On Intel Pineview M hardware, the i915 gallium driver doesn't output the
correct gl_FragCoord. It seems to always have an X coord of 0.0 and a Y coo=
rd
of the window's height in pixels, e.g. 600.0f or such.
I believe this is a regression caused in part by commit
afa035031ff9e0c07a2297d864e46c76f7bfff58
(https://lists.freedesktop.org/archives/mesa-commit/2016-Janua=
ry/061181.html)
The old behavior used output zero, while the new behavior uses actual zeroe=
s.
In the case of gl_FragCoord output zero happened to be the correct one.
I've attached a patch that seems to fix the issue for me. I ran the piglit
"quick" tests and observed 17 new tests passing, and one regressi=
on. I suspect
the regression is unimportant since it involves derivatives that aren't
implemented for this driver anyway:
"fs-dfdy-accuracy" test failed ... in i915_fpc_translate.c:
case TGSI_OPCODE_DDY:
/* XXX We just output 0 here */
debug_printf("Punting DDX/DDX\n");