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List:       freedesktop-xorg
Subject:    Re: 2048 size limit on virtual displays
From:       Brian Paul <brian.paul () tungstengraphics ! com>
Date:       2008-04-29 14:27:27
Message-ID: 4817304F.7070206 () tungstengraphics ! com
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Keith Packard wrote:
> On Tue, 2008-04-29 at 00:32 +0100, Albert Vilella wrote:
>> is this on a i965? can this be used for a i945?
> 
> Nope, the i945 has a hardware limit of 2048x2048 for textures and 3d
> rendering targets. The i965 has a 8192x8192 limit, but Mesa has a
> 4096x4096 limit, so I set the i965 driver to that value. At some point,
> perhaps Mesa will be fixed to handle larger outputs, but that appears
> difficult given the existing Mesa software rendering stack.

To be more specific, the issue is in triangle rasterization using fixed 
point arithmetic.  You can set MAX_WIDTH/HEIGHT to 8192 in 
src/mesa/main/config.h and things would probably be fine for the most 
part.  But in some situations, particular triangles might be slightly 
mis-rendered.  Most people never notice/care, but in some applications, 
tiny errors in triangle rasterization are significant.

There are additional comments in src/mesa/swrast/s_tritemp.h

-Brian

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