On 9/25/06, The Rasterman Carsten Haitzler <[EMAIL PROTECTED]> wrote: > On Mon, 25 Sep 2006 10:50:09 -0700 Blake Barnett <[EMAIL PROTECTED]> babbled: > > > > > On Sep 25, 2006, at 10:44 AM, David Sharp wrote: > > > > > amd64 users, rejoice! > > > > > > i got tired of slowing down e with -mfpmath=387 all the time, so i > > > finally dug in to this bug after realizing it was probably a problem > > > with floating point cancelation (occurs when subtracting two numbers > > > that are very near equal, and causes an extreme loss of precision). > > > > > > the problem is in _edje_part_recalc() when it linearly interpolates > > > all the part parameters. all of the caclulations are of this form: > > > p3.x = (p1.x * (1.0 - pos)) + (p2.x * (pos)); > > > i believe there is some cancelation occuring in the (1.0-pos) part of > > > this, especially as pos approaches 1.0. > > > > > > replacing the above line with the following fixes the problem: > > > p3.x = p1.x + (p2.x - p1.x) * pos; > > > mathematically equivalent, but, alas, computers aren't as good at math > > > as we think. > > > > Awesome! My 3500+ CPU has felt fairly sluggish in E, my video card > > has 128MB of video memory (ATI 9700PRO, using ATI's drivers) and I've > > noticed that things just aren't as fluid as in Rasters video > > captures. Hopefully this'll help. Nice work. > > it won't make any difference you can measure. the amount of fp math done is < > 0.1% of the work - by using sse math you lose a bit of precision and maybe > gain > 50% speedup - on that < 0.01%. frankly- you will not be able to even measure > the speedup letalone notice it. it's a fallacy to think it will help. trust > me.
yah, it will only save about 37 instructions (b/c the new formulas use one less operation, and there are 37 of them), and the sse instructions will only be slightly faster than the FPU ones. that's a savings of about, say 25 ns each time _edje_part_recalc is run. btw, you gave blake my credit in the CVS log... :( d# > > fluid or not will have nothing to do with fp math. :) it will fix BUGS where > things jerk about due to cumulative loss of precision with 64bit fp math. > > > -Blake > > > > ------------------------------------------------------------------------- > > 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 > > _______________________________________________ > > enlightenment-devel mailing list > > enlightenment-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/enlightenment-devel > > > > > -- > ------------- Codito, ergo sum - "I code, therefore I am" -------------- > The Rasterman (Carsten Haitzler) [EMAIL PROTECTED] > 裸好多 > Tokyo, Japan (東京 日本) > -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? ------------------------------------------------------------------------- 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 _______________________________________________ enlightenment-devel mailing list enlightenment-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/enlightenment-devel
