Anuj Phogat
fb1bc5007d
There are no standard sample positions defined in OpenGL and OpenGL
ES specs. Implementations have the freedom to pick the positions
which give plausible results. But the Vulkan 1.0 spec does define
standard sample positions for different sample counts. Defined
positions in Vulkan for all the sample counts except 8X match with
the positions we set in i965. We have an upcoming plan to share the
blorp code between OpenGL and Vulkan driver in near future. Keeping
the 8X sample positions same on both the drivers will help us move
in that direction.
Here is an argument by Neil Roberts (from commit 20250e85) against
any advantage of current 8X sample positions over the new ones:
"The comment above for the 8x sample positions says that the hardware
implements centroid interpolation by picking the centre-most sample
that is inside the primitive. That implies that it might be worthwhile
to pick a pattern that includes 0.5,0.5. However by experimentation
this doesn't seem to actually be the case. With the sample positions
in this patch, if I modify the piglit test below so that it instead
reports the centroid position, it reports 0.492188,0.421875 which
doesn't match any of the positions. If I modify the sample positions
so that they include one at exactly 0.5,0.5 it doesn't help and it
reports another position which is even further from the center for
some reason.
arb_gpu_shader5-interpolateAtSample-different
Kenneth Graunke experimented with some other patterns that have a
higher standard deviation but I think after some discussion it was
decided that it would be better to pick the same pattern as the other
graphics API in case there are games that rely on this pattern."
Observed no regressions in jenkins testing.
Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
File: docs/README.WIN32 Last updated: 21 June 2013 Quick Start ----- ----- Windows drivers are build with SCons. Makefiles or Visual Studio projects are no longer shipped or supported. Run scons libgl-gdi to build gallium based GDI driver. This will work both with MSVS or Mingw. Windows Drivers ------- ------- At this time, only the gallium GDI driver is known to work. Source code also exists in the tree for other drivers in src/mesa/drivers/windows, but the status of this code is unknown. Recipe ------ Building on windows requires several open-source packages. These are steps that work as of this writing. - install python 2.7 - install scons (latest) - install mingw, flex, and bison - install pywin32 from here: http://www.lfd.uci.edu/~gohlke/pythonlibs get pywin32-218.4.win-amd64-py2.7.exe - install git - download mesa from git see http://www.mesa3d.org/repository.html - run scons General ------- After building, you can copy the above DLL files to a place in your PATH such as $SystemRoot/SYSTEM32. If you don't like putting things in a system directory, place them in the same directory as the executable(s). Be careful about accidentially overwriting files of the same name in the SYSTEM32 directory. The DLL files are built so that the external entry points use the stdcall calling convention. Static LIB files are not built. The LIB files that are built with are the linker import files associated with the DLL files. The si-glu sources are used to build the GLU libs. This was done mainly to get the better tessellator code. If you have a Windows-related build problem or question, please post to the mesa-dev or mesa-users list.