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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#365F91'>Maybe this should go to the developer’s list, if so let me know.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>I have occasionally had problems with nVidia video cards showing odd renderings of polydata object (shell/stl files with explicit normals). Up until now, changing the driver has fixed the problem (it’s not necessarily the latest and greatest drivers that work, sometimes the solution is to use older ones). Well, I just got an nVidia Quadro FX3800 in a new machine and I cannot find the magic bullet to make the problem go away, so I need the wisdom of the list gods to help out.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>Here’s the problem in graphical form: <a href="http://www.lifemodeler.com/eric/snapshot.html">http://www.lifemodeler.com/eric/snapshot.html</a><o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>When the object in question is originally rendered, everything is fine. When I create a second view in the application (VTK inside wxWidgets) containing the same geometry, swapping back and forth between the two views causes this rendering error.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>Here are some clues:<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:#365F91'><span style='mso-list:Ignore'>1)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#365F91'>Not the hardware. I swap the video card into a Windows XP Pro 32-bit machine and cannot reproduce the problem. Problematic machine is Win7 Pro 64-bit, the problem follows the OS (we’ve put the card into three machines now, 2x Win7 and 1x XP).<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:#365F91'><span style='mso-list:Ignore'>2)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#365F91'>We don’t see the problem in any other software, including other OGL-using CAD, CAM and CAE packages.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:#365F91'><span style='mso-list:Ignore'>3)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#365F91'>Does not happen on the “bad” machines when a Quadro FX1700 card is installed with the same driver versions. Does not happen with ATI FirePro V7800 on the “bad” machines.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:#365F91'><span style='mso-list:Ignore'>4)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#365F91'>Anything that causes the view to re-render (zoom, pan, or attribute changes on any object in the view), fixes the rendering and it looks “good” again.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:#365F91'><span style='mso-list:Ignore'>5)<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:#365F91'>In the past, this sort of render-mangling has happened on arbitrary objects, but in this current manifestation, it only appears to affect things with opacity != 1.0.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>I dug through both the developer and user archives, found something about texture maps causing problems when they were non-power-of-2 sized, but that’s not it, as I can turn off all texture maps and see the same problem (besides, all my texture maps are 256x, or 512x…).<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>Does anyone have ideas on how I can diagnose this? It sort of looks to me like the normals are backwards on the polydata object, but what would that mean?<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#365F91'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#365F91'>Eric<o:p></o:p></span></p></div></body></html>