piglit/tests/general/line-aa-width has been fail since Eric added it on June 15th: http://cgit.freedesktop.org/piglit/commit/?id=6e3195bcb51a3d32b0d3fdc31b5c16732f751c2b On i965: Line from 0,2-30,3 had bad thickness: min coverage: 0.137255 avg coverage: 0.800302 max coverage: 1.000000 Line from 30,3-60,6 had bad thickness: min coverage: 0.407843 avg coverage: 0.834389 max coverage: 1.000000 PIGLIT: {'result': 'fail' } On i915: Output: Line from 0,2-30,3 had bad thickness: min coverage: 0.062745 avg coverage: 0.555354 max coverage: 1.000000 Line from 30,3-60,6 had bad thickness: min coverage: 0.125490 avg coverage: 0.552941 max coverage: 1.000000 Line from 60,6-90,12 had bad thickness: min coverage: 0.250980 avg coverage: 0.596229 max coverage: 1.000000 Line from 90,12-120,20 had bad thickness: min coverage: 0.313726 avg coverage: 0.637104 max coverage: 1.000000
I've played with this test a lot trying to fix it with no luck. We've had bug reports of bad rendering in real apps from this, but it appears to be hard to get a good result out of the AA line support in the HW.
WIP changes that don't actually fix the problem: http://cgit.freedesktop.org/~anholt/mesa/log/?h=i965-line-aa
*** Bug 27007 has been marked as a duplicate of this bug. ***
*** Bug 9951 has been marked as a duplicate of this bug. ***
Created attachment 95780 [details] [review] Patch Thanks to previous work by Eric Anholt, I have been playing with line width to fix this bug. The patch increases the line width by 0.25f when GL_LINE_SMOOTH is enabled, making the HW AA algorithm to give better results without increasing a lot the line width. This patch also fixes bug 60797. It has been tested on SandyBridge and IvyBridge.
*** Bug 60797 has been marked as a duplicate of this bug. ***
(In reply to comment #5) I have tested the patch on my Lenovo X220 with Sandybridge graphics. Horizontal and vertical lines stop to disappear, but yellow lines are depicted very dark yellow-ish. From my point of view, the patch improves the situation, but does not solve it.
The Windows driver generally works a lot better for line rendering. It would be great if someone at Intel could figure out how they map the GL API settings to the hardware settings, and make Mesa do the same thing.
2 patches for IVB ad SNB was send to the mesa mailing list. Setting a Line Width of 0.0 specifies the rasterization of the “thinnest” (one-pixel-wide), non-antialiased lines. Lines rendered with zero Line Width are rasterized using GIQ (Grid Intersection Quantization) rules as specified by the GDI and Direct3D APIs. For more digging ,see bspec section 6.3.12.1 Zero-Width (Cosmetic) Line Rasterization.
The patches that fix this bug is up-streamed
It has been fixed on i965 platforms. On i915 platforms, it fails with mesa master and 10.5 branch. Report bug 90367 to track it. Close this bug.
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