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Add rotation_between_axis/scaled_rotation_between_axis.

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This commit is contained in:
Sébastien Crozet 2018-02-02 12:26:25 +01:00
parent dc41b55e5a
commit 52598de44c
2 changed files with 55 additions and 14 deletions
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3
CHANGELOG.md
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@ -12,6 +12,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
`::from_element(...)`.
* The `.iamin()` methods that returns the index of the vector entry with
smallest absolute value.
* `UnitQuaternion::scaled_rotation_between_axis` and
`UnitQuaternion::rotation_between_axis` that take Unit vectors instead of
Vector as arguments.

66
src/geometry/quaternion_construction.rs
View File

@ -207,24 +207,62 @@ impl<N: Real> UnitQuaternion<N> {
where SB: Storage<N, U3>,
SC: Storage<N, U3> {
// FIXME: code duplication with Rotation.
if let (Some(na), Some(nb)) = (a.try_normalize(N::zero()), b.try_normalize(N::zero())) {
let c = na.cross(&nb);
if let (Some(na), Some(nb)) = (Unit::try_new(a.clone_owned(), N::zero()),
Unit::try_new(b.clone_owned(), N::zero())) {
Self::scaled_rotation_between_axis(&na, &nb, s)
}
else {
Some(Self::identity())
}
}
if let Some(axis) = Unit::try_new(c, N::default_epsilon()) {
return Some(Self::from_axis_angle(&axis, na.dot(&nb).acos() * s))
/// The unit quaternion needed to make `a` and `b` be collinear and point toward the same
/// direction.
#[inline]
pub fn rotation_between_axis<SB, SC>(a: &Unit<Vector<N, U3, SB>>, b: &Unit<Vector<N, U3, SC>>) -> Option<Self>
where SB: Storage<N, U3>,
SC: Storage<N, U3> {
Self::scaled_rotation_between_axis(a, b, N::one())
}
/// The smallest rotation needed to make `a` and `b` collinear and point toward the same
/// direction, raised to the power `s`.
#[inline]
pub fn scaled_rotation_between_axis<SB, SC>(na: &Unit<Vector<N, U3, SB>>,
nb: &Unit<Vector<N, U3, SC>>,
s: N)
-> Option<Self>
where SB: Storage<N, U3>,
SC: Storage<N, U3> {
// FIXME: code duplication with Rotation.
let c = na.cross(&nb);
if let Some(axis) = Unit::try_new(c, N::default_epsilon()) {
let cos = na.dot(&nb);
// The cosinus may be out of [-1, 1] because of innacuracies.
if cos <= -N::one() {
return None
}
// Zero or PI.
if na.dot(&nb) < N::zero() {
// PI
//
// The rotation axis is undefined but the angle not zero. This is not a
// simple rotation.
return None;
else if cos >= N::one() {
return Some(Self::identity())
}
else {
return Some(Self::from_axis_angle(&axis, cos.acos() * s))
}
}
Some(Self::identity())
else if na.dot(&nb) < N::zero() {
// PI
//
// The rotation axis is undefined but the angle not zero. This is not a
// simple rotation.
return None;
}
else {
// Zero
Some(Self::identity())
}
}