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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>medium
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Casting floating point variable to integer not working properly while constant gets converted properly"
href="https://bugs.freedesktop.org/show_bug.cgi?id=70327">70327</a>
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<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
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<th>Summary</th>
<td>Casting floating point variable to integer not working properly while constant gets converted properly
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Reporter</th>
<td>tony.wasserka@dolphin-emu.org
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<th>Hardware</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>git
</td>
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<th>Component</th>
<td>Drivers/Gallium/r600
</td>
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<th>Product</th>
<td>Mesa
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=87353" name="attach_87353" title="Full rendered scene with bug visible">attachment 87353</a> <a href="attachment.cgi?id=87353&action=edit" title="Full rendered scene with bug visible">[details]</a></span>
Full rendered scene with bug visible
I've recently been working on converting the shaders used by the Dolphin
emulator to use integers instead of floating point numbers (for better
emulation accuracy). This seems to have exposed a bug in the r600g driver
possibly related to float->int casting.
The core of the issue is this GLSL code line:
"iprev.rgb = (iprev.rgb * (int(256.0-fog))) / 256;" (*)
where fog has been initialized before as
"float fog = clamp(ze - fog_uniform.z, 0.0, 1.0);"
The point is, while "fog" seems to be zero (a "fog==0.0" condition in the code
will return true), the pixel shader result of (*) is different than the one
that I get by substituting "fog" with 0.0. This gets very apparent in the
rendered scene, cf</pre>
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