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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [llvmpipe] Front/Backfaces do not get the same depth values when interpolated"
href="https://bugs.freedesktop.org/show_bug.cgi?id=78914#c24">Comment # 24</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [llvmpipe] Front/Backfaces do not get the same depth values when interpolated"
href="https://bugs.freedesktop.org/show_bug.cgi?id=78914">bug 78914</a>
from <span class="vcard"><a class="email" href="mailto:jfonseca@vmware.com" title="José Fonseca <jfonseca@vmware.com>"> <span class="fn">José Fonseca</span></a>
</span></b>
<pre>(In reply to Kurzemnieks from <a href="show_bug.cgi?id=78914#c23">comment #23</a>)
<span class="quote">> I think I have run in the same problem.
> Here is a screenshot with a simple double-sided cube whose backface seems to
> be drawn incorrectly on the edge.
> <a href="https://api1-ams2.monosnap.com/static/0kwtTWiNWJrcIXex8BcxpgoWCkxHGx.png">https://api1-ams2.monosnap.com/static/0kwtTWiNWJrcIXex8BcxpgoWCkxHGx.png</a></span >
Link is dead.
Maybe try using Buzilla's attachment feature -- might be good for future
reference too.
<span class="quote">> So what is the best workaround for this if it won't be fixed?</span >
The "workaround" (although I'd merely call it "best practice") is to make
adequate use of glPolygonOffset.
See for example <a href="http://www.zeuscmd.com/tutorials/opengl/15-PolygonOffset.php">http://www.zeuscmd.com/tutorials/opengl/15-PolygonOffset.php</a>
In short the whole idea consists in: instead of assuming that two draw calls
will produce _exactly_ the same depth values, give a tolerance so to accomodate
small differences. glPolygonOffset allows to do that.</pre>
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