Thanks a lot for the comments, Roland. This confirms my understanding. Since there seems not to be any more feedback, I will now send the patch for conversion tests I was working on for piglit's review.
Thanks again. :) On Tue, 2016-04-05 at 16:29 +0200, Roland Scheidegger wrote: > Pretty sure this should be all undefined. double->int isn't really > any > different than float->int there where you can have values which are > too > large too. > Note that for float->int (and it should be the same for doubles) > d3d10 > requires that you clamp to destination type range, and NaN gets > converted to 0. Hence why implementations tend to do this. But still > undefined in glsl (which, of course, doesn't mean someone might not > rely > on d3d10 behaviour there...). > > Roland > > > Am 05.04.2016 um 09:33 schrieb Andres Gomez: > > > > Hi, > > > > I haven't had any other feedback than Ilia's (thanks Ilia!) so my > > doubts still stand. > > > > I'd welcome more info regarding this topic. > > > > Thanks! > > > > Br. > > > > On Tue, 2016-03-15 at 17:46 +0200, Andres Gomez wrote: > > > > > > Hi, > > > > > > as complementary work to the one done to "Add FP64 support to the > > > i965 > > > shader backends" at: > > > https://bugs.freedesktop.org/show_bug.cgi?id=92760 > > > > > > I've been working to add piglit tests that would check the new > > > features > > > added by this addition. > > > > > > One of the topics we have been creating tests for is > > > implicit/explicit > > > conversion from and to doubles in GLSL. We have created already a > > > generator for it but have some doubts about what to expect when > > > dealing > > > with conversions from a value out of range in the destination > > > type. > > > > > > Specifically, I'm talking about negative doubles explicitly > > > converted > > > into unsigned int or too big negative or positive double values > > > converted into int or unsigned int. > > > > > > What I've observed from running with the NVIDIA proprietary > > > driver or > > > with other backends is that, typically, the conversion will > > > result in > > > a > > > value which is the lowest or the highest defined in the > > > destination > > > type, depending on the side of the happening overflow. > > > > > > However, I've been unable to find documentation in the GLSL specs > > > specifying how the conversions should work in this cases. > > > > > > My conclusion is that the behavior is undefined and will depend > > > on > > > implementation. Hence, we won't add tests for these cases. > > > > > > Opinions? > > > > > > _______________________________________________ > > > mesa-dev mailing list > > > [email protected] > > > https://lists.freedesktop.org/mailman/listinfo/mesa-dev > -- Br, Andres
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