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<th>Priority</th>
<td>medium
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<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - i965: Using EWA algorithm for isotropic case"
href="https://bugs.freedesktop.org/show_bug.cgi?id=82463">82463</a>
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<th>Assignee</th>
<td>idr@freedesktop.org
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<th>Summary</th>
<td>i965: Using EWA algorithm for isotropic case
</td>
</tr>
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<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Reporter</th>
<td>pavel.e.popov@intel.com
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>10.2
</td>
</tr>
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<th>Component</th>
<td>Drivers/DRI/i965
</td>
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<th>Product</th>
<td>Mesa
</td>
</tr></table>
<p>
<div>
<pre>Tests "MesaDemos tests/texfilt" and Test "MesaDemos tests/mipmap_tunnel"
started to show an expected results (the transition from one mipmap level to
another should be nice and regular/circular) for anisotropic case (2x - 16x)
after EWA algorithm was enabled in Mesa:
<a href="http://cgit.freedesktop.org/mesa/mesa/commit/?id=f74cf5f80ea6ea16abb38c28c2b4826b8559017b">http://cgit.freedesktop.org/mesa/mesa/commit/?id=f74cf5f80ea6ea16abb38c28c2b4826b8559017b</a>
But for isotropic case (1x) something like a polar rose is still observed. The
screenshots are attached below. This is because EWA algorithm was enabled in
Mesa only for anisotropic case.
But EWA algorithm also can be enabled for isotropic case. At least Haswell
programming notes (Volume 2d: Command Reference: Structures(Haswell), Page 271)
contains the following lines:
"When EWA used for non-anisotropic filtering and the coordinates have zero
derivative the computed LOD is 0 instead of -inf."
I enabled EWA algorithm for isotropic case too and expected results were
observed for both tests. The screenshots are attached below.
Also I run these tests on Nvidia and observed that they also work as expected.
The screenshots are attached below.
Could we use EWA for isotropic case? Or just say that this polar rose is ok for
isotropic case and performance is more important for us here.</pre>
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