Sounds like I better look at this more carefully, it is quite possible it is producing bad filters but with small enough error that the images look OK. <div class="gmail_quote">On Dec 23, 2015 5:25 AM, "Oded Gabbay" <<a href="mailto:oded.gabbay@gmail.com">oded.gabbay@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Tue, Dec 22, 2015 at 9:01 PM, Bill Spitzak <<a href="mailto:spitzak@gmail.com">spitzak@gmail.com</a>> wrote: > > > On Tue, Dec 22, 2015 at 4:38 AM, Oded Gabbay <<a href="mailto:oded.gabbay@gmail.com">oded.gabbay@gmail.com</a>> wrote: >> >> On Sat, Dec 12, 2015 at 8:06 PM, <<a href="mailto:spitzak@gmail.com">spitzak@gmail.com</a>> wrote: >> > From: Bill Spitzak <<a href="mailto:spitzak@gmail.com">spitzak@gmail.com</a>> >> > >> > The other filters do not check for x being in range, so there is >> > no reason for cubic to do so. >> >> This argument is a bit problematic. >> We could also argue that this filter was actually implemented >> correctly/more robust and we should add checks for x to the other >> filters. >> >> I fail to see how this saves us much except from removing a condition >> in a very specific path. >> >> Do you argue that ax will never ever be >=2 ? > > > Yes, because if that could happen, then out-of-range x could also be sent to > the other filter functions that are not doing the range check. > I run the scale demo, and added a printf everytime ax is >=2. I got a LOT of prints... So I don't think your argument is correct. > Adding range checks to all the other filters (especially the ones that > return constants) would add a bunch of conditions that are never used. Maybe, but it might be necessary to produce more accurate results ? Oded > >> >> >> Oded >> >> > --- >> > pixman/pixman-filter.c | 16 +++++++--------- >> > 1 file changed, 7 insertions(+), 9 deletions(-) >> > >> > diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c >> > index 7e10108..bf9dce3 100644 >> > --- a/pixman/pixman-filter.c >> > +++ b/pixman/pixman-filter.c >> > @@ -109,18 +109,16 @@ general_cubic (double x, double B, double C) >> > >> > if (ax < 1) >> > { >> > - return ((12 - 9 * B - 6 * C) * ax * ax * ax + >> > - (-18 + 12 * B + 6 * C) * ax * ax + (6 - 2 * B)) / 6; >> > - } >> > - else if (ax >= 1 && ax < 2) >> > - { >> > - return ((-B - 6 * C) * ax * ax * ax + >> > - (6 * B + 30 * C) * ax * ax + (-12 * B - 48 * C) * >> > - ax + (8 * B + 24 * C)) / 6; >> > + return (((12 - 9 * B - 6 * C) * ax + >> > + (-18 + 12 * B + 6 * C)) * ax * ax + >> > + (6 - 2 * B)) / 6; >> > } >> > else >> > { >> > - return 0; >> > + return ((((-B - 6 * C) * ax + >> > + (6 * B + 30 * C)) * ax + >> > + (-12 * B - 48 * C)) * ax + >> > + (8 * B + 24 * C)) / 6; >> > } >> > } >> > >> > -- >> > 1.9.1 >> > >> > _______________________________________________ >> > Pixman mailing list >> > <a href="mailto:Pixman@lists.freedesktop.org">Pixman@lists.freedesktop.org</a> >> > <a href="http://lists.freedesktop.org/mailman/listinfo/pixman" rel="noreferrer" target="_blank">http://lists.freedesktop.org/mailman/listinfo/pixman</a> > > </blockquote></div>