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use std::ops::*;
use num_traits::{NumOps, NumAssignOps, Signed};
use num_traits::pow::Pow;
use num_traits::real::Real;
macro_rules! fold_array {
($method:ident, { $x:expr }) => { $x };
($method:ident, { $x:expr, $y:expr }) => { $x.$method($y) };
($method:ident, { $x:expr, $y:expr, $z:expr }) => { $x.$method($y).$method($z) };
}
macro_rules! impl_vector {
($VecN:ident { $($field:ident),+ }) => {
#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq)]
pub struct $VecN<T> {
$(pub $field: T),+
}
impl<T> $VecN<T> {
pub const fn new($($field: T),+) -> $VecN<T> {
$VecN { $($field),+ }
}
}
impl<T: NumOps + Ord + Signed + Copy> $VecN<T> {
pub fn walking_distance(&self) -> T {
fold_array!(max, { $(self.$field.abs()),+ })
}
}
impl<T: NumOps + Pow<u8, Output=T> + Copy> $VecN<T> {
pub fn magnitude_squared(&self) -> T {
fold_array!(add, { $(self.$field.pow(2)),+ })
}
}
impl<T: Real + Pow<u8, Output=T>> $VecN<T> {
pub fn magnitude(&self) -> T {
self.magnitude_squared().sqrt()
}
pub fn unit(&self) -> $VecN<T> {
let mag = self.magnitude();
$VecN {
$($field: self.$field / mag),+
}
}
}
impl<T: NumOps + Copy> $VecN<T> {
pub fn dot(&self, other: $VecN<T>) -> T {
fold_array!(add, { $(self.$field * other.$field),+ })
}
}
impl<T: NumOps> Add for $VecN<T> {
type Output = Self;
fn add(self, other: Self) -> Self {
$VecN {
$($field: self.$field + other.$field),+
}
}
}
impl<T: NumAssignOps> AddAssign for $VecN<T> {
fn add_assign(&mut self, other: Self) {
$(self.$field += other.$field);+
}
}
impl<T: NumOps> Sub for $VecN<T> {
type Output = Self;
fn sub(self, other: Self) -> Self {
$VecN {
$($field: self.$field - other.$field),+
}
}
}
impl<T: NumOps + Copy> Mul<T> for $VecN<T> {
type Output = Self;
fn mul(self, rhs: T) -> Self {
$VecN {
$($field: self.$field * rhs),+
}
}
}
impl<T: Neg<Output=T>> Neg for $VecN<T> {
type Output = Self;
fn neg(self) -> Self {
$VecN {
$($field: -self.$field),+
}
}
}
}
}
impl_vector!(Vec2d { x, y });
impl_vector!(Vec3d { x, y, z });
impl<T: Real + Pow<u8, Output=T>> Vec2d<T> {
pub fn angle(&self) -> T {
self.y.atan2(self.x)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn right_angles_in_2d_vectors() {
use std::f32::consts::{FRAC_PI_2, PI};
assert_eq!(0., Vec2d::new(1., 0.).angle());
assert_eq!(FRAC_PI_2, Vec2d::new(0., 1.).angle());
assert_eq!(PI, Vec2d::new(-1., 0.).angle());
assert_eq!(-FRAC_PI_2, Vec2d::new(0., -1.).angle());
}
#[test]
fn unit_normalizes_2d_vector() {
let before = Vec2d::new(2., 10.);
let after = before.unit();
assert_eq!(1., after.magnitude());
assert_eq!(before.angle(), after.angle());
}
#[test]
fn unit_normalizes_3d_vector() {
let before = Vec3d::new(2., 10., -5.);
let after = before.unit();
assert_eq!(1., after.magnitude());
// How to define 3d angle? 2 angles I suppose?
// assert_eq!(before.angle(), after.angle());
}
#[test]
fn dot_product_example_2d() {
let a = Vec2d::new(-6., 8.);
let b = Vec2d::new(5., 12.);
assert_eq!(66., a.dot(b));
}
#[test]
fn magnitude_squared_of_an_integer() {
let a = Vec2d::new(3, 4);
assert_eq!(25, a.magnitude_squared());
}
}
|
