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use std::ops::Mul;
use bytemuck::{Pod, Zeroable};
use crate::vec::Vec2;
#[repr(C)]
#[derive(Debug, Clone, Copy, Pod, Zeroable)]
pub struct GpuTransform2d {
// col0 col1 col2 col3
// [m11, [m12, [m13, [0,
// m21, m22, m23, 0,
// 0, 0, 1, 0,
// 0] 0] 0] 1]
pub matrix: [[f32; 4]; 4],
}
impl From<Transform2d> for GpuTransform2d {
fn from(t: Transform2d) -> Self {
let [m11, m21, m12, m22, m13, m23] = t.matrix;
Self {
matrix: [
[m11, m21, 0. , 0. ],
[m12, m22, 0. , 0. ],
[0. , 0. , 1. , 0. ],
[m13, m23, 0. , 1. ],
],
}
}
}
#[derive(Debug, Clone, Copy)]
pub struct Transform2d {
// represents
// [ m11 m12 m13 ]
// [ m21 m22 m23 ]
// [ 0 0 1 ]
// with indices
// [ 0 2 4 ]
// [ 1 3 5 ]
// [ N/A N/A N/A ]
pub matrix: [f32; 6],
}
impl Default for Transform2d {
fn default() -> Self {
Self::identity()
}
}
impl Transform2d {
/// Returns the identity transform — no translation, rotation, or scale.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::identity();
/// let p = Vec2::new(3., 4.);
/// assert_eq!(t.transform_point(p), p);
/// ```
pub fn identity() -> Self {
Self {
matrix: [
1., 0.,
0., 1.,
0., 0.,
]
}
}
/// Applies `self` first, then `other`, returning the composed transform.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::translation(1., 0.).then(Transform2d::scaling(2., 2.));
/// let p = t.transform_point(Vec2::new(1., 0.));
/// assert_eq!(p, Vec2::new(4., 0.)); // translated first, then scaled
/// ```
pub fn then(self, other: Self) -> Self {
other.mul(self)
}
/// Returns a transform that translates by `(x, y)`.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::translation(5., -3.);
/// assert_eq!(t.transform_point(Vec2::new(1., 1.)), Vec2::new(6., -2.));
/// ```
pub fn translation(x: f32, y: f32) -> Self {
Self {
matrix: [
1., 0.,
0., 1.,
x, y,
]
}
}
/// Applies an additional translation of `(x, y)` after `self` and returns the result.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let mut t = Transform2d::scaling(2., 2.);
/// let t2 = t.translate(3., 1.);
/// assert_eq!(t2.transform_point(Vec2::new(1., 1.)), Vec2::new(5., 3.));
/// ```
pub fn translate(&mut self, x: f32, y: f32) -> Self {
self.then(Self::translation(x, y))
}
/// Returns a transform that rotates by `rad` radians, counter-clockwise.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::rotation_rad(std::f32::consts::FRAC_PI_2);
/// let p = t.transform_point(Vec2::new(1., 0.));
/// assert!((p.x - 0.).abs() < 1e-6);
/// assert!((p.y - 1.).abs() < 1e-6);
/// ```
pub fn rotation_rad(rad: f32) -> Self {
let (sin, cos) = rad.sin_cos();
Self {
matrix: [
cos, sin,
-sin, cos,
0., 0.,
]
}
}
/// Applies an additional counter-clockwise rotation of `rad` radians after `self` and returns the result.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let mut t = Transform2d::translation(1., 0.);
/// let t2 = t.rotate_rad(std::f32::consts::FRAC_PI_2);
/// let p = t2.transform_point(Vec2::new(0., 0.));
/// assert!((p.x - 0.).abs() < 1e-6);
/// assert!((p.y - 1.).abs() < 1e-6);
/// ```
pub fn rotate_rad(&mut self, rad: f32) -> Self {
self.then(Self::rotation_rad(rad))
}
/// Returns a transform that rotates by `deg` degrees, counter-clockwise.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::rotation_deg(90.);
/// let p = t.transform_point(Vec2::new(1., 0.));
/// assert!((p.x - 0.).abs() < 1e-6);
/// assert!((p.y - 1.).abs() < 1e-6);
/// ```
pub fn rotation_deg(deg: f32) -> Self {
let (sin, cos) = deg.to_radians().sin_cos();
Self {
matrix: [
cos, sin,
-sin, cos,
0., 0.,
]
}
}
/// Applies an additional counter-clockwise rotation of `deg` degrees after `self` and returns the result.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let mut t = Transform2d::translation(1., 0.);
/// let t2 = t.rotate_deg(90.);
/// let p = t2.transform_point(Vec2::new(0., 0.));
/// assert!((p.x - 0.).abs() < 1e-6);
/// assert!((p.y - 1.).abs() < 1e-6);
/// ```
pub fn rotate_deg(&mut self, deg: f32) -> Self {
*self = self.then(Self::rotation_deg(deg));
*self
}
/// Returns a transform that scales by `sx` horizontally and `sy` vertically.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::scaling(2., 3.);
/// assert_eq!(t.transform_point(Vec2::new(1., 1.)), Vec2::new(2., 3.));
/// ```
pub fn scaling(sx: f32, sy: f32) -> Self {
Self {
matrix: [
sx, 0.,
0., sy,
0., 0.,
]
}
}
/// Applies an additional scale of `sx` horizontally and `sy` vertically after `self` and returns the result.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::translation(1., 1.).scale(2., 3.);
/// assert_eq!(t.transform_point(Vec2::new(0., 0.)), Vec2::new(2., 3.));
/// ```
pub fn scale(self, sx: f32, sy: f32) -> Self {
self.then(Transform2d::scaling(sx, sy))
}
/// Applies this transform to a 2D point.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::translation(1., 2.);
/// assert_eq!(t.transform_point(Vec2::new(3., 4.)), Vec2::new(4., 6.));
/// ```
pub fn transform_point(self, p: Vec2) -> Vec2 {
let [m11, m21, m12, m22, m13, m23] = self.matrix;
Vec2::new(
m11 * p.x + m12 * p.y + m13,
m21 * p.x + m22 * p.y + m23,
)
}
/// Returns the scale factors encoded in this transform as a [`Vec2`],
/// extracted from the column magnitudes of the rotation/scale portion of the matrix.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
///
/// let t = Transform2d::scaling(2., 3.).then(Transform2d::rotation_deg(45.));
/// let s = t.get_scale();
/// assert!((s.x - 2.).abs() < 1e-6);
/// assert!((s.y - 3.).abs() < 1e-6);
/// ```
pub fn get_scale(self) -> Vec2 {
Vec2::new(
(self.matrix[0] * self.matrix[0] + self.matrix[1] * self.matrix[1]).sqrt(),
(self.matrix[2] * self.matrix[2] + self.matrix[3] * self.matrix[3]).sqrt(),
)
}
}
impl Mul for Transform2d {
type Output = Self;
/// Multiplies two transforms together, composing them into a single transform.
/// The result applies `other` first, then `self`.
///
/// # Example
/// ```
/// use verdant::{transform::Transform2d, vec::Vec2};
/// use std::ops::Mul;
///
/// let t = Transform2d::translation(2., 0.).mul(Transform2d::scaling(2., 2.));
/// let p = t.transform_point(Vec2::new(1., 0.));
/// assert_eq!(p, Vec2::new(4., 0.)); // scaled first, then translated
/// ```
fn mul(self, rhs: Self) -> Self::Output {
let [lm11, lm21, lm12, lm22, lm13, lm23] = self.matrix;
let [rm11, rm21, rm12, rm22, rm13, rm23] = rhs.matrix;
let m11 = lm11 * rm11 + lm12 * rm21;
let m21 = lm21 * rm11 + lm22 * rm21;
let m12 = lm11 * rm12 + lm12 * rm22;
let m22 = lm21 * rm12 + lm22 * rm22;
let m13 = lm11 * rm13 + lm12 * rm23 + lm13; // translation x
let m23 = lm21 * rm13 + lm22 * rm23 + lm23; // translation y
Self {
matrix: [
m11, m21,
m12, m22,
m13, m23,
]
}
}
}