<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - [llvmpipe] Front/Backfaces do not cover the same pixels when rasterized" href="https://bugs.freedesktop.org/show_bug.cgi?id=78914#c19">Comment # 19</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - [llvmpipe] Front/Backfaces do not cover the same pixels when rasterized" href="https://bugs.freedesktop.org/show_bug.cgi?id=78914">bug 78914</a> from <a class="email" href="mailto:sroland@vmware.com" title="Roland Scheidegger <sroland@vmware.com>"> Roland Scheidegger</a> <pre>depth test as such is as accurate as it could be. Doing interpolation with as much precision as possible is not all that easy due to properties of floating point arithmetic. In particular for the math the order of vertices matter. Reordering would be possible, though still does not guarantee the same results for fragments along a shared edge (unless the tri shares all vertices, that is it's really the same tri with reordered edges). But I agree doing better would be nice, I'm just not entirely sure what clever tricks need to be done to achieve this. There's also a slight bug in the implementation I believe, the interpolation should be done with snapped (fixed point) coordinates, however we do the interpolation setup with float coordinates. I'm not sure though this would help here, but at least in contrast to other interpolation issues this one wouldn't be all that difficult to fix. Another issue is that if you have some attributes with large gradients on a somewhat small triangle, you can get huge errors the further the triangle is away from the framebuffer origin. So, interpolation is definitely not perfect.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>