pxl8/pxl8d/src/math.rs

use core::ops::{Add, Mul, Sub};

#[repr(C)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Vec2 {
    pub x: f32,
    pub y: f32,
}

#[repr(C)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Vec3 {
    pub x: f32,
    pub y: f32,
    pub z: f32,
}

#[repr(C)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Vec4 {
    pub x: f32,
    pub y: f32,
    pub z: f32,
    pub w: f32,
}

#[repr(C)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Mat4 {
    pub m: [f32; 16],
}

#[allow(non_camel_case_types)]
pub type pxl8_vec2 = Vec2;
#[allow(non_camel_case_types)]
pub type pxl8_vec3 = Vec3;
#[allow(non_camel_case_types)]
pub type pxl8_vec4 = Vec4;
#[allow(non_camel_case_types)]
pub type pxl8_mat4 = Mat4;

impl Vec3 {
    pub const ZERO: Vec3 = Vec3 { x: 0.0, y: 0.0, z: 0.0 };
    pub const Y: Vec3 = Vec3 { x: 0.0, y: 1.0, z: 0.0 };

    pub fn new(x: f32, y: f32, z: f32) -> Self {
        Self { x, y, z }
    }

    pub fn dot(self, rhs: Self) -> f32 {
        self.x * rhs.x + self.y * rhs.y + self.z * rhs.z
    }

    pub fn cross(self, rhs: Self) -> Self {
        Self {
            x: self.y * rhs.z - self.z * rhs.y,
            y: self.z * rhs.x - self.x * rhs.z,
            z: self.x * rhs.y - self.y * rhs.x,
        }
    }

    pub fn length(self) -> f32 {
        libm::sqrtf(self.dot(self))
    }

    pub fn normalize(self) -> Self {
        let len_sq = self.dot(self);
        if len_sq < 1e-12 {
            return Self::ZERO;
        }
        self * (1.0 / libm::sqrtf(len_sq))
    }
}

impl Add for Vec3 {
    type Output = Self;
    fn add(self, rhs: Self) -> Self {
        Self {
            x: self.x + rhs.x,
            y: self.y + rhs.y,
            z: self.z + rhs.z,
        }
    }
}

impl Sub for Vec3 {
    type Output = Self;
    fn sub(self, rhs: Self) -> Self {
        Self {
            x: self.x - rhs.x,
            y: self.y - rhs.y,
            z: self.z - rhs.z,
        }
    }
}

impl Mul<f32> for Vec3 {
    type Output = Self;
    fn mul(self, rhs: f32) -> Self {
        Self {
            x: self.x * rhs,
            y: self.y * rhs,
            z: self.z * rhs,
        }
    }
}