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Groups > comp.lang.c > #401153
| From | BGB <cr88192@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Default signedness of 'plain' char. |
| Date | 2026-08-14 03:16 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <115mj6i$2ccfd$1@dont-email.me> (permalink) |
| References | (16 earlier) <115dv3d$3k3jl$1@dont-email.me> <115feen$3msd$1@dont-email.me> <115g1p6$aeop$2@dont-email.me> <115m73a$285f3$2@dont-email.me> <115masb$294v7$1@dont-email.me> |
On 8/14/2026 12:59 AM, Lawrence D’Oliveiro wrote:
> On Thu, 13 Aug 2026 23:50:16 -0500, BGB wrote:
>
>> SLERP'ing between identity and a given rotation allows scaling the
>> rotation;
>
> You can’t linearly interpolate the sines and cosines, though. If you
> want to do linear interpolation of the rotation angle, don’t you have
> to compute inverse sines/cosines, calculate new angles and then back
> again?
This is where it can get funny:
While naive interpolation goes off the unit-sphere, re-normalizing the
quaternion generally puts it back at around the position it would have
been had one followed an arc over the surface of the hyper-sphere
between these points (at least within +/- 180 degrees, and not
necessarily at a uniform velocity if the distance is large).
This is both more convenient and cheaper than using sines or cosines or
trying to follow an arc. One can use them, but don't need to.
More accuracy (and more uniform speed) is possible with a normalized
LERP though by using a subdivision trick similar to that used for
matrices if the points are further apart, though in this case it is a
little cheaper, say:
qnlerp(A,B,f)
if(qdist2(A,B)<CUTOFF)
return qnormalize(A*(1-f)+(B+f));
C=qnormalize((A+B)*0.5);
if(frac<0.5)
return qnlerp(A,C,f*2);
return qnlerp(C,B,f*2-1);
Though, they still come up if moving to/from axis/angle or similar.
As can be noted, multiplying rotations also effectively concatenates them.
Can't really explain how it works...
Granted, there are some weird cases that need to be worked around, but
mostly it all "just sorta works"...
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Default signedness of 'plain' char. gazelle@shell.xmission.com (Kenny McCormack) - 2026-08-02 14:17 +0000
Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-03 02:45 +0800
Re: Default signedness of 'plain' char. gazelle@shell.xmission.com (Kenny McCormack) - 2026-08-03 01:47 +0000
Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-03 23:14 +0800
Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-03 17:04 +0100
The Spanish Inquisition (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-04 00:23 +0800
Re: The Spanish Inquisition bart <bc@freeuk.com> - 2026-08-03 18:03 +0100
Re: The Spanish Inquisition Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-04 01:26 +0800
Re: Default signedness of 'plain' char. Theo <theom+news@chiark.greenend.org.uk> - 2026-08-04 13:13 +0100
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:30 +0000
Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:18 +0800
Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-05 17:20 +0100
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:57 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 15:29 -0700
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-03 09:56 +0200
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-03 13:56 -0500
Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-03 13:48 +0000
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-03 14:47 +0000
Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-03 14:47 +0000
Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-03 15:04 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-03 16:58 -0700
Re: Default signedness of 'plain' char. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2026-08-04 15:10 +0000
Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-04 15:50 +0000
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 03:00 +0000
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-05 09:01 +0200
Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-04 18:10 +0000
Compilers targetting the C64 (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 03:17 +0800
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-04 16:25 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 02:57 +0000
Re: Default signedness of 'plain' char. Lynn McGuire <lynnmcguire5@gmail.com> - 2026-08-05 00:19 -0500
Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:57 +0800
Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-05 14:33 +0000
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-05 22:38 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-04 21:36 -0700
Re: Default signedness of 'plain' char. antispam@fricas.org (Waldek Hebisch) - 2026-08-06 00:21 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 13:20 -0700
Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-03 22:06 +0100
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 14:25 -0700
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-03 18:38 -0500
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-03 19:34 -0700
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-05 04:40 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:22 +0000
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-05 04:02 -0500
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-05 12:35 +0200
Re: Default signedness of 'plain' char. Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-05 18:49 +0800
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-05 12:39 -0700
Dear Chris (was: Re: Default signedness of 'plain' char.) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-06 20:15 +0800
Re: Dear Chris bart <bc@freeuk.com> - 2026-08-06 15:05 +0100
Re: Dear Chris Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-06 23:16 +0800
Re: Dear Chris David Brown <david.brown@hesbynett.no> - 2026-08-06 20:10 +0200
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:54 +0000
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-06 04:49 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-07 00:10 +0000
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-07 09:56 +0200
Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-05 13:33 -0400
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 21:50 +0000
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-06 10:34 +0200
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-09 15:19 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-09 20:33 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-09 18:04 -0700
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-10 02:45 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-10 02:24 -0700
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-09 18:03 -0700
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-10 08:58 +0200
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 15:17 -0500
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-10 15:19 -0700
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 17:31 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-10 23:48 +0000
Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-10 20:03 -0400
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-10 20:44 -0500
Re: Default signedness of 'plain' char. James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-08-11 11:17 -0400
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-11 14:54 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-12 03:36 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-12 01:24 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-12 07:47 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 12:52 -0700
Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 12:56 -0700
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 02:16 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-12 21:04 -0700
Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-12 23:07 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 05:00 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 04:37 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-13 14:36 -0700
Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 23:07 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-13 23:44 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-13 18:50 -0700
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 02:41 +0000
Re: Quaternions (was Re: Default signedness of 'plain' char.) BGB <cr88192@gmail.com> - 2026-08-13 23:47 -0500
Re: Quaternions (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 04:59 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 13:47 -0700
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-13 23:50 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 05:59 +0000
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-14 03:16 -0500
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-14 08:32 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 12:36 -0700
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-15 03:16 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 22:38 -0700
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-16 00:08 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-14 12:17 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-11 13:46 +0000
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 13:49 -0700
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-11 08:58 +0200
Re: Default signedness of 'plain' char. BGB <cr88192@gmail.com> - 2026-08-11 04:03 -0500
Re: Default signedness of 'plain' char. steve g <Sgonedes1977@gmail.com> - 2026-08-10 20:29 -0400
Re: Vectors! Quaternions! (was Re: Default signedness of 'plain' char.) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-11 03:58 +0000
Re: Default signedness of 'plain' char. David Brown <david.brown@hesbynett.no> - 2026-08-11 09:06 +0200
Re: Default signedness of 'plain' char. Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-08-10 21:15 -0700
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-11 04:52 +0000
Re: Default signedness of 'plain' char. Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-08-11 06:45 -0700
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-11 14:01 -0700
Re: Default signedness of 'plain' char. "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-08-05 12:36 -0700
Re: Default signedness of 'plain' char. Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-05 07:18 +0000
Re: Default signedness of 'plain' char. Lynn McGuire <lynnmcguire5@gmail.com> - 2026-08-05 18:30 -0500
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 16:41 -0700
Re: Default signedness of 'plain' char. bart <bc@freeuk.com> - 2026-08-06 01:24 +0100
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-05 17:46 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-06 22:59 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 19:54 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 11:02 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 10:35 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 18:32 +0000
Re: Default signedness of 'plain' char. Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 20:55 +0200
Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 20:51 +0200
Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 13:03 -0700
Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 13:32 -0700
Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 21:44 +0000
Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-08-07 23:47 +0200
Re: Use of isascii() back in early days (was Re: Default signedness of 'plain' char.) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-07 15:26 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-06 22:57 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 18:23 -0700
Re: Default signedness of 'plain' char. cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-07 11:47 +0000
Re: Default signedness of 'plain' char. scott@slp53.sl.home (Scott Lurndal) - 2026-08-06 14:40 +0000
Re: Default signedness of 'plain' char. Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-08-06 15:33 -0700
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