use na::{Real, DefaultAllocator};
use traits::{Number, Alloc, Dimension};
use aliases::{TVec, TVec3};
pub fn cross<N: Number, D: Dimension>(x: &TVec3<N>, y: &TVec3<N>) -> TVec3<N> {
x.cross(y)
}
pub fn distance<N: Real, D: Dimension>(p0: &TVec<N, D>, p1: &TVec<N, D>) -> N
where DefaultAllocator: Alloc<N, D> {
(p1 - p0).norm()
}
pub fn dot<N: Number, D: Dimension>(x: &TVec<N, D>, y: &TVec<N, D>) -> N
where DefaultAllocator: Alloc<N, D> {
x.dot(y)
}
pub fn faceforward<N: Number, D: Dimension>(n: &TVec<N, D>, i: &TVec<N, D>, nref: &TVec<N, D>) -> TVec<N, D>
where DefaultAllocator: Alloc<N, D> {
if nref.dot(i) < N::zero() {
n.clone()
} else {
-n.clone()
}
}
pub fn length<N: Real, D: Dimension>(x: &TVec<N, D>) -> N
where DefaultAllocator: Alloc<N, D> {
x.norm()
}
pub fn magnitude<N: Real, D: Dimension>(x: &TVec<N, D>) -> N
where DefaultAllocator: Alloc<N, D> {
x.norm()
}
pub fn normalize<N: Real, D: Dimension>(x: &TVec<N, D>) -> TVec<N, D>
where DefaultAllocator: Alloc<N, D> {
x.normalize()
}
pub fn reflect_vec<N: Number, D: Dimension>(i: &TVec<N, D>, n: &TVec<N, D>) -> TVec<N, D>
where DefaultAllocator: Alloc<N, D> {
let _2 = N::one() + N::one();
i - n * (n.dot(i) * _2)
}
pub fn refract_vec<N: Real, D: Dimension>(i: &TVec<N, D>, n: &TVec<N, D>, eta: N) -> TVec<N, D>
where DefaultAllocator: Alloc<N, D> {
let ni = n.dot(i);
let k = N::one() - eta * eta * (N::one() - ni * ni);
if k < N::zero() {
TVec::<_, D>::zeros()
}
else {
i * eta - n * (eta * dot(n, i) + k.sqrt())
}
}