On 2/14/07, Rune Petersen <[EMAIL PROTECTED]> wrote: > Roland Scheidegger wrote: > > Roland Scheidegger wrote: > >>>> Rune Petersen > >>>> > >>> Ok commited. > >> I didn't look too closely at this but I've a couple of comments. > >> - COS looks too complicated & broken. If you'd want to get 2 with a > >> LOG2, you'd need 0.25 as source. But even using RCP instead, that's 5 > >> instructions before performing the sine, for something you can easily do > >> in two, using another constant (just 1 add + 1 cmp needed, if you use > >> the right constants for the add). Maybe it's not that bad though, I > >> don't know how many rgb and a slots it will actually consume, but still, > >> are constant slots that rare? > >> Second, you'd really need to do range reduction of the input, otherwise > >> results will be very wrong for inputs outside [-pi, pi]. This would be > >> true for taylor approximation too, of course, unless you do an infinite > >> series :-). You wouldn't need to do that for SCS. > > > > Oh, and forgot to mention, you probably really want to use the higher > > precision variant by default. 12% max relative error (and even absolute > > it's still 6%) will likely be visible in some cases depending what the > > shader is doing. Even the enhanced version seems to miss opengl > > conformance (accurate to "about 1 part in 10^5") by roughly a factor of > > 10, which stretches the meaning of "about" a bit probably already. > > You could also rely on the precision hint for fragment programs to > > switch to the faster version instead of a dri conf option (note though > > the spec explicitly states implementations are discouraged even in this > > case to perform optimizations which could have significant impact on the > > output). > > > This patch: > - Fixes COS. > - Does range reductions for SIN & COS. > - Adds SCS. > - removes the optimized version of SIN & COS. > - tweaked weight (should help on precision). > - fixed a copy paste typo in emit_arith(). > > Roland would you mind testing if the tweaked weight helped? > > And Jerome would you mind committing this? > > > Rune Petersen >
Pushed, git isn't so frightening trust me :) best, Jerome Glisse ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
