use std::ops;
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Vec2 {
pub x: f64,
pub y: f64,
}
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Transform {
e: [f64; 6],
}
impl ops::Add for Vec2 {
type Output = Self;
fn add(self, other: Self) -> Self {
Vec2::new(self.x + other.x, self.y + other.y)
}
}
impl ops::Sub for Vec2 {
type Output = Self;
fn sub(self, other: Self) -> Self {
Vec2::new(self.x - other.x, self.y - other.y)
}
}
impl ops::Mul<f64> for Vec2 {
type Output = Self;
fn mul(self, s: f64) -> Self {
Vec2::new(self.x * s, self.y * s)
}
}
impl ops::Mul for Vec2 {
type Output = f64;
fn mul(self, other: Self) -> f64 {
self.x * other.y - self.y * other.x
}
}
impl ops::Div<f64> for Vec2 {
type Output = Self;
fn div(self, s: f64) -> Self {
Vec2::new(self.x / s, self.y / s)
}
}
impl ops::Neg for Vec2 {
type Output = Self;
fn neg(self) -> Self {
Vec2::new(-self.x, -self.y)
}
}
impl Vec2 {
pub fn new(x: f64, y: f64) -> Self {
Vec2 { x, y }
}
pub fn zero() -> Self {
Vec2::new(0.0, 0.0)
}
pub fn mag(self) -> f64 {
self.x.hypot(self.y)
}
pub fn normalize(self) -> Self {
let m = self.mag();
if m > 0.0 {
self / m
} else {
Vec2::zero()
}
}
pub fn dist_sq(self, other: Self) -> f64 {
let dx = self.x - other.x;
let dy = self.y - other.y;
dx * dx + dy * dy
}
pub fn dist(self, other: Self) -> f64 {
self.dist_sq(other).sqrt()
}
}
impl ops::MulAssign for Transform {
fn mul_assign(&mut self, other: Self) {
self.e = self.mul_e(&other);
}
}
impl ops::Mul for Transform {
type Output = Self;
fn mul(self, other: Self) -> Self {
let e = self.mul_e(&other);
Transform { e }
}
}
impl ops::Mul<Vec2> for Transform {
type Output = Vec2;
fn mul(self, s: Vec2) -> Vec2 {
let x = self.e[0] * s.x + self.e[1] * s.y + self.e[2];
let y = self.e[3] * s.x + self.e[4] * s.y + self.e[5];
Vec2::new(x, y)
}
}
impl Transform {
pub fn new() -> Self {
Transform {
e: [1.0, 0.0, 0.0, 0.0, 1.0, 0.0],
}
}
fn mul_e(&self, other: &Self) -> [f64; 6] {
let mut e = [0.0; 6];
e[0] = self.e[0] * other.e[0] + self.e[3] * other.e[1];
e[1] = self.e[1] * other.e[0] + self.e[4] * other.e[1];
e[2] = self.e[2] * other.e[0] + self.e[5] * other.e[1] + other.e[2];
e[3] = self.e[0] * other.e[3] + self.e[3] * other.e[4];
e[4] = self.e[1] * other.e[3] + self.e[4] * other.e[4];
e[5] = self.e[2] * other.e[3] + self.e[5] * other.e[4] + other.e[5];
e
}
pub fn new_translate(tx: f64, ty: f64) -> Self {
Transform {
e: [1.0, 0.0, tx, 0.0, 1.0, ty],
}
}
pub fn new_scale(sx: f64, sy: f64) -> Self {
Transform {
e: [sx, 0.0, 0.0, 0.0, sy, 0.0],
}
}
pub fn new_rotate(th: f64) -> Self {
let sn = th.sin();
let cs = th.cos();
Transform {
e: [cs, -sn, 0.0, sn, cs, 0.0],
}
}
pub fn new_skew(ax: f64, ay: f64) -> Self {
let tnx = ax.tan();
let tny = ay.tan();
Transform {
e: [1.0, tnx, 0.0, tny, 1.0, 0.0],
}
}
pub fn translate(mut self, tx: f64, ty: f64) -> Self {
self *= Transform::new_translate(tx, ty);
self
}
pub fn scale(mut self, sx: f64, sy: f64) -> Self {
self *= Transform::new_scale(sx, sy);
self
}
pub fn rotate(mut self, th: f64) -> Self {
self *= Transform::new_rotate(th);
self
}
pub fn skew(mut self, ax: f64, ay: f64) -> Self {
self *= Transform::new_skew(ax, ay);
self
}
}
#[cfg(test)]
mod test {
use super::*;
use std::f64;
#[test]
fn test_vec2() {
let a = Vec2::new(2.0, 1.0);
let b = Vec2::new(3.0, 4.0);
assert_eq!(a + b, Vec2::new(5.0, 5.0));
assert_eq!(b - a, Vec2::new(1.0, 3.0));
assert_eq!(a * 2.0, Vec2::new(4.0, 2.0));
assert_eq!(a / 2.0, Vec2::new(1.0, 0.5));
assert_eq!(-a, Vec2::new(-2.0, -1.0));
assert_eq!(b.mag(), 5.0);
assert_eq!(a.dist_sq(b), 10.0);
assert_eq!(b.dist(Vec2::new(0.0, 0.0)), 5.0);
}
#[test]
fn test_identity() {
assert_eq!(Transform::new().e, [1.0, 0.0, 0.0, 0.0, 1.0, 0.0]);
assert_eq!(
(Transform::new() * Transform::new()).e,
[1.0, 0.0, 0.0, 0.0, 1.0, 0.0]
);
assert_eq!(Transform::new() * Vec2::new(1.0, 2.0), Vec2::new(1.0, 2.0));
}
#[test]
fn test_translate() {
assert_eq!(
Transform::new_translate(1.5, -1.5).e,
[1.0, 0.0, 1.5, 0.0, 1.0, -1.5]
);
assert_eq!(
Transform::new().translate(2.5, -3.5).e,
[1.0, 0.0, 2.5, 0.0, 1.0, -3.5]
);
assert_eq!(
Transform::new().translate(5.0, 7.0) * Vec2::new(1.0, -2.0),
Vec2::new(6.0, 5.0)
);
}
#[test]
fn test_scale() {
assert_eq!(
Transform::new_scale(2.0, 4.0).e,
[2.0, 0.0, 0.0, 0.0, 4.0, 0.0]
);
assert_eq!(
Transform::new().scale(3.0, 5.0).e,
[3.0, 0.0, 0.0, 0.0, 5.0, 0.0]
);
assert_eq!(
Transform::new().scale(2.0, 3.0) * Vec2::new(1.5, -2.0),
Vec2::new(3.0, -6.0)
);
}
#[test]
fn test_skew() {
const PI: f64 = f64::consts::PI;
assert_eq!(
Transform::new().skew(0.0, PI / 4.0) * Vec2::new(15.0, 7.0),
Vec2::new(15.0, 22.0)
);
}
#[test]
fn test_transform() {
assert_eq!(
(Transform::new_translate(1.0, 2.0) * Transform::new_scale(2.0, 2.0)).e,
[2.0, 0.0, 2.0, 0.0, 2.0, 4.0]
);
assert_eq!(
Transform::new_translate(3.0, 5.0)
* Transform::new_scale(7.0, 11.0)
* Transform::new_rotate(f64::consts::PI / 2.0)
* Transform::new_skew(1.0, -2.0),
Transform::new()
.translate(3.0, 5.0)
.scale(7.0, 11.0)
.rotate(f64::consts::PI / 2.0)
.skew(1.0, -2.0)
);
}
}