From: <bug...@fr...> - 2010-01-03 13:01:47
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http://bugs.freedesktop.org/show_bug.cgi?id=25871 Summary: nearest neighbour samples wrong texel (precision/rounding problem) Product: Mesa Version: git Platform: Other OS/Version: All Status: NEW Severity: normal Priority: medium Component: Drivers/DRI/R600 AssignedTo: dri...@li... ReportedBy: pie...@os... The following fragment program does the wrong thing on r600/r700 hardware: TEX result.color, 0.498046860099, texture[0], 2D; (the texture coord is as far as I got before I got bored. I'm not sure the precision goes much further anyway) The circumstances is that I have a 4x4 texture with nearest neighbour interpolation. The above code should be sampling texel 1,1 but is instead sampling texel 2,2. This causes problems for fragment programs that try to do things based on texel coords (like bicubic interpolation). This seems to be a hw bug as I've tried it with fglrx (albeit with a slightly different card) and it exhibits the same bug. As such, I'm not sure it can be solved but hopefully there is a workaround. -- Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug. |