nalgebra/examples/dimensional_genericity.rs

61 lines
2.0 KiB
Rust

extern crate nalgebra as na;
use na::allocator::Allocator;
use na::dimension::Dim;
use na::{DefaultAllocator, RealField, Unit, Vector2, Vector3, VectorN};
/// Reflects a vector wrt. the hyperplane with normal `plane_normal`.
fn reflect_wrt_hyperplane_with_dimensional_genericity<N: RealField, D: Dim>(
plane_normal: &Unit<VectorN<N, D>>,
vector: &VectorN<N, D>,
) -> VectorN<N, D>
where
N: RealField,
D: Dim,
DefaultAllocator: Allocator<N, D>,
{
let n = plane_normal.as_ref(); // Get the underlying V.
vector - n * (n.dot(vector) * na::convert(2.0))
}
/// Reflects a 2D vector wrt. the 2D line with normal `plane_normal`.
fn reflect_wrt_hyperplane2<N>(plane_normal: &Unit<Vector2<N>>, vector: &Vector2<N>) -> Vector2<N>
where
N: RealField,
{
let n = plane_normal.as_ref(); // Get the underlying Vector2
vector - n * (n.dot(vector) * na::convert(2.0))
}
/// Reflects a 3D vector wrt. the 3D plane with normal `plane_normal`.
/// /!\ This is an exact replicate of `reflect_wrt_hyperplane2, but for 3D.
fn reflect_wrt_hyperplane3<N>(plane_normal: &Unit<Vector3<N>>, vector: &Vector3<N>) -> Vector3<N>
where
N: RealField,
{
let n = plane_normal.as_ref(); // Get the underlying Vector3
vector - n * (n.dot(vector) * na::convert(2.0))
}
fn main() {
let plane2 = Vector2::y_axis(); // 2D plane normal.
let plane3 = Vector3::y_axis(); // 3D plane normal.
let v2 = Vector2::new(1.0, 2.0); // 2D vector to be reflected.
let v3 = Vector3::new(1.0, 2.0, 3.0); // 3D vector to be reflected.
// We can call the same function for 2D and 3D.
assert_eq!(
reflect_wrt_hyperplane_with_dimensional_genericity(&plane2, &v2).y,
-2.0
);
assert_eq!(
reflect_wrt_hyperplane_with_dimensional_genericity(&plane3, &v3).y,
-2.0
);
// Call each specific implementation depending on the dimension.
assert_eq!(reflect_wrt_hyperplane2(&plane2, &v2).y, -2.0);
assert_eq!(reflect_wrt_hyperplane3(&plane3, &v3).y, -2.0);
}