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| author | rodri <rgl@antares-labs.eu> | 2023-01-27 22:57:21 +0000 |
|---|---|---|
| committer | rodri <rgl@antares-labs.eu> | 2023-01-27 22:57:21 +0000 |
| commit | fdeaa2423c582df8d9e9ae6b0e26d386b5531262 (patch) | |
| tree | 26762f0636448354a5c8e6c62756009120dd353e /quaternion.c | |
| parent | 278c3d3be924246488226ae89e67616955dce661 (diff) | |
| download | libgeometry-fdeaa2423c582df8d9e9ae6b0e26d386b5531262.tar.gz libgeometry-fdeaa2423c582df8d9e9ae6b0e26d386b5531262.tar.bz2 libgeometry-fdeaa2423c582df8d9e9ae6b0e26d386b5531262.zip | |
bring the slerp function, make ptinpoly public and clean some of the code.
Diffstat (limited to 'quaternion.c')
| -rw-r--r-- | quaternion.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/quaternion.c b/quaternion.c index 686c04e..ca44747 100644 --- a/quaternion.c +++ b/quaternion.c @@ -78,6 +78,24 @@ normq(Quaternion q) return sdivq(q, qlen(q)); } +/* + * based on the implementation from: + * + * Jonathan Blow, “Understanding Slerp, Then Not Using it”, + * The Inner Product, April 2004. + */ +Quaternion +slerp(Quaternion q, Quaternion r, double t) +{ + Quaternion v; + double θ, q·r; + + q·r = fclamp(dotq(q, r), -1, 1); /* stay within the domain of acos(2) */ + θ = acos(q·r)*t; + v = normq(subq(r, smulq(q, q·r))); /* v = r - (q·r)q / |v| */ + return addq(smulq(q, cos(θ)), smulq(v, sin(θ))); /* q cos(θ) + v sin(θ) */ +} + Point3 qrotate(Point3 p, Point3 axis, double θ) { |