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<p class=MsoNormal>Hi all,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span lang=EN-US>We are currently using a modified volume-rendering
mapper based on the “vtkVolumeTextureMapper3D” and “vtkOpenGLVolumeTextureMapper3D”.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>During our development we encountered a bug
on some nvidia drivers (at least on windows vista 64, driver ver. 190.38):<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Even though this drivers support
non-power-of-two textures,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>They will crash the application, when
allocating the texture with a “uneven” size in the first dimension.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>As an example: our CT data with a
resolution of 391x290x226 results in display artifacts and strange crashs
later.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>If u modify following section (line 1044 in
vtkVolumeTextureMapper3D.cxx)<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>
if(this->SupportsNonPowerOfTwoTextures)<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> {<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> for ( int i = 0; i
< 3; i++ )<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> {<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>
powerOfTwoDim[i]=dim[i];<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>with following section:<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>
if(this->SupportsNonPowerOfTwoTextures)<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> {<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> for ( int i = 0; i
< 3; i++ )<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> {<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>
powerOfTwoDim[i]=(dim[i]+1)&~1;<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>the internal texture resolution will be
rounded up to the next even number in all dimensions.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Hope this helps people having problems with
using the vtkVolumeTextureMapper3D and some nvidia drivers.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>However we can’t provide a detection
algorithm for the bug in the drivers, since its seems many are affected
(32bit/64bit, Windows XP/Vista/7, and different versions).<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>We always enable this workaround, since its
resource impact is very small.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US> <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Greetings,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Markus Fangerau<o:p></o:p></span></p>
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