<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - Centroid shouldn't have to match between the FS and the VS" href="https://bugs.freedesktop.org/show_bug.cgi?id=92743#c8">Comment # 8</a> on <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - Centroid shouldn't have to match between the FS and the VS" href="https://bugs.freedesktop.org/show_bug.cgi?id=92743">bug 92743</a> from <a class="email" href="mailto:lemody@gmail.com" title="Tapani Pälli <lemody@gmail.com>"> Tapani Pälli</a> <pre>(In reply to Corentin Wallez from <a href="show_bug.cgi?id=92743#c5">comment #5</a>) > Here is a copy-paste of a bug I filed against dEQP that explains the > situation. I'm not sure what the right step forward is yet, we might have to > file a Khronos bug to have a resolution. In the meantime the centroid-only > patch seems safe to merge, but not the other one. > > The GLES3.functional.shaders.linkage.varying.rules.differing_interpolation_2 > test tests that these two varyings correctly link together. > - smooth out mediump float var; > - centroid in mediump float var; > The differences between the variables is two-fold, no-centroid vs. centroid > and smooth interpolation vs. default interpolation. The spec says that > centroid and no-centroid is ok, see longer explanation in the first comment > of <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - Centroid shouldn't have to match between the FS and the VS" href="show_bug.cgi?id=92743">https://bugs.freedesktop.org/show_bug.cgi?id=92743</a> > However the spec unclear on the smooth vs. default being allowed. The GLSL > ES 3.0.4 and GLSL 330 spec say in the interpolation section that: > The type and presence of the interpolation qualifiers and storage > qualifiers and invariant qualifiers of variables with the same name declared > in all linked shaders must match, otherwise the link command will fail. (end > of section 4.3.9 of the GLSL ES 3.0.4 spec) > Which seems to indicate that default vs. smooth is not valid since default > is the absence of qualifier. > > However in bug <a href="https://cvs.khronos.org/bugzilla/show_bug.cgi?id=7819">https://cvs.khronos.org/bugzilla/show_bug.cgi?id=7819</a> a block > of text was added to the spec starting from GLSL 430 stating that the > interpolation qualifiers do not have to link, and that the fragment shader's > one is the one that gets used. So starting from that point on, the spec > contradicts itself. > > Now the question is whether the edit to GLSL 430 spec shows what the intent > was all along, in which case we should ignore all the previous spec text on > the presence having to match. Or it is something that should start to take > effect only with the GLSL 430 spec onward in which case there is a spec bug > for these versions. GLSL 440 spec removed the contradictory statement: "<a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - [R300] low impact fallbacks and blender" href="show_bug.cgi?id=10990">Bug 10990</a>: Remove old contradictory text requiring interpolation qualifiers to match cross stage; they must only match within a stage." This is how Mesa works currently, interpolation is checked against only if GLSL version is < 440.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>