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Make slerp method implementation a little easier to understand

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This commit is contained in:
Brendan Zabarauskas 2012-12-08 12:59:37 +10:00
parent b4fbb9c76a
commit 4bd14e4d50
1 changed files with 14 additions and 10 deletions
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24
src/quat.rs
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@ -388,18 +388,22 @@ pub impl<T:Copy Float Exp Extent InvTrig> Quat<T>: Quaternion<T, Vec3<T>> {
pure fn slerp(&self, other: &Quat<T>, amount: T) -> Quat<T> {
let dot = self.dot(other);
// if quaternions are close together use `nlerp`
let dot_threshold = Number::from(0.9995);
if dot > dot_threshold { return self.nlerp(other, amount) }
let robust_dot = dot.clamp(&-Number::from(1), &Number::from(1)); // stay within the domain of acos()
let theta_0 = acos(&robust_dot); // the angle between the quaternions
let theta = theta_0 * amount; // the fraction of theta specified by `amount`
let q = other.sub_q(&self.mul_t(robust_dot))
.normalize();
self.mul_t(cos(&theta)).add_q(&q.mul_t(sin(&theta)))
if dot > dot_threshold {
return self.nlerp(other, amount); // if quaternions are close together use `nlerp`
} else {
let robust_dot = dot.clamp(&-Number::from(1),
&Number::from(1)); // stay within the domain of acos()
let theta_0 = acos(&robust_dot); // the angle between the quaternions
let theta = theta_0 * amount; // the fraction of theta specified by `amount`
let q = other.sub_q(&self.mul_t(robust_dot))
.normalize();
return self.mul_t(cos(&theta)).add_q(&q.mul_t(sin(&theta)));
}
}
#[inline(always)]