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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - i915g: gl_FragCoord is always (0.0, max_y)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97477">97477</a>
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<th>Summary</th>
<td>i915g: gl_FragCoord is always (0.0, max_y)
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<th>Product</th>
<td>Mesa
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<th>Version</th>
<td>git
</td>
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<th>Hardware</th>
<td>Other
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>Drivers/Gallium/i915g
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<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
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<th>Reporter</th>
<td>nicholasbishop@gmail.com
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<th>QA Contact</th>
<td>dri-devel@lists.freedesktop.org
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<pre>Created <span class=""><a href="attachment.cgi?id=126029" name="attach_126029" title="Patch: Handle I915_SEMANTIC_POS when setting texCoords for gl_FragCoord">attachment 126029</a> <a href="attachment.cgi?id=126029&action=edit" title="Patch: Handle I915_SEMANTIC_POS when setting texCoords for gl_FragCoord">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=97477&attachment=126029'>[review]</a>
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 coord
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
(<a href="https://lists.freedesktop.org/archives/mesa-commit/2016-January/061181.html">https://lists.freedesktop.org/archives/mesa-commit/2016-January/061181.html</a>)
The old behavior used output zero, while the new behavior uses actual zeroes.
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 regression. 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");</pre>
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