pbrt/src/utils/types.rs

use std::ops::{Sub, Add, Div, Mul, Neg, Index, IndexMut};
use num_traits::{Num, Float, Bounded};

pub trait Tuple<const N: usize, T> : Index<usize, Output = T> + IndexMut<usize> + Copy {
    fn get(&self, i: usize) -> T; 
    fn set(&mut self, i: usize, val: T);
    fn has_nan(&self) -> bool where T: Float {
        for i in 0..N {
            if self.get(i).is_nan() {
                return true
            }
        }
        false
    }
}

#[derive(Copy, Clone, PartialEq)]
pub struct Vector2<T> { pub x: T, pub y: T }
#[derive(Copy, Clone, PartialEq)]
pub struct Point2<T> { pub x: T, pub y: T }
#[derive(Copy, Clone, PartialEq)]
pub struct Vector3<T> { pub x: T, pub y: T, pub z: T }
#[derive(Copy, Clone, PartialEq)]
pub struct Normal3<T> { pub x: T, pub y: T, pub z: T }
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Point3<T> { pub x: T, pub y: T, pub z : T }

// Using macros to make this more concise
macro_rules! impl_tuple3 {
    ($Struct:ident, [$($field:ident), +]) => {
        impl<T> $Struct<T> {
            pub fn new($($field: T), +) -> Self { Self { $($field), + }}
        }

        impl<T: Num + Copy> $Struct<T> {
            pub fn dot(&self, other: Self) -> T {
                self.x * other.x + self.y * other.y + self.z * other.z
            }

            pub fn length_squared(self) -> T {
                self.dot(self)
            }
        }

        impl<T: Float> $Struct<T> {
            pub fn length(self) -> T {
                self.length_squared().sqrt()
            }

            pub fn normalize(self) -> Self {
                self / self.length()
            }
        }

        // Operators
        impl<T: Add<Output=T>> Add for $Struct<T> {
            type Output = Self;
            fn add(self, rhs: Self) -> Self { Self::new(self.x + rhs.x, self.y + rhs.y, self.z + rhs.z )}
        }

        impl<T: Mul<Output=T> + Copy > Mul<T> for $Struct<T> {
            type Output = Self;
            fn mul(self, rhs: T) -> Self { Self::new(self.x * rhs, self.y * rhs, self.z * rhs )}
        }

        impl<T: Div<Output=T> + Copy > Div<T> for $Struct<T> {
            type Output = Self;
            fn div(self, rhs: T) -> Self { Self::new(self.x / rhs, self.y / rhs, self.z / rhs )}
        }

        impl<T: Neg<Output=T>> Neg for $Struct<T> {
            type Output = Self;
            fn neg(self) -> Self { Self::new(-self.x, -self.y, -self.z)}
        }

        impl<T> Index<usize> for $Struct<T> {
            type Output = T;
            fn index(&self, i: usize) -> &T {
                match i { 0 => &self.x, 1 => &self.y, 2 => &self.z, _ => panic!("Index out of bonds") }
            }
        }

        impl<T> IndexMut<usize> for $Struct<T> {
            fn index_mut(&mut self, i: usize) -> &mut T {
                match i { 0 => &mut self.x, 1 => &mut self.y, 2 => &mut self.z, _ => panic!("Index out of bonds") }
            }
        }
    };
} 

macro_rules! impl_component_ops {
    ($Struct:ident) => {
        impl<T: Sub<Output=T>> Sub for $Struct<T> {
            type Output = Self;
            fn sub(self, rhs: Self) -> Self { Self::new(self.x - rhs.x, self.y - rhs.y, self.z - rhs.z) }
        }
    }
}

impl_tuple3!(Vector3, [x, y, z]);
impl_tuple3!(Point3, [x, y, z]);
impl_tuple3!(Normal3, [x, y, z]);
impl_component_ops!(Vector3);
impl_component_ops!(Normal3);

// Point3 - Point3 -> Vector3
impl<T: Sub<Output = T>> Sub<Point3<T>> for Point3<T> {
    type Output = Vector3<T>;
    fn sub(self, rhs: Point3<T>) -> Vector3<T> {
        Vector3::new(self.x - rhs.x, self.y - rhs.y, self.z - rhs.z)
    }
}

// Point3 + Vector3 -> Point3
impl<T: Add<Output = T>> Add<Vector3<T>> for Point3<T> {
    type Output = Point3<T>;
    fn add(self, rhs: Vector3<T>) -> Point3<T> {
        Point3::new(self.x + rhs.x, self.y + rhs.y, self.z + rhs.z)
    }
}

// Point3 - Vector3 -> Point3
impl<T: Sub<Output = T>> Sub<Vector3<T>> for Point3<T> {
    type Output = Point3<T>;
    fn sub(self, rhs: Vector3<T>) -> Point3<T> {
        Point3::new(self.x - rhs.x, self.y - rhs.y, self.z - rhs.z)
    }
}


// Cross Product for Vector3
impl<T: Num + Copy> Vector3<T> {
    pub fn cross(self, other: Vector3<T>) -> Vector3<T> {
        Vector3 {
            x: self.y * other.z - self.z * other.y,
            y: self.z * other.x - self.x * other.z,
            z: self.x * other.y - self.y * other.x,
        }
    }
}


pub type Point3f = Point3<f32>;
pub type Point3i = Point3<i32>;
pub type Vector3f = Vector3<f32>;
pub type Vector3i = Vector3<i32>;
pub type Normal3f = Normal3<f32>;
pub type Normal3i = Normal3<i32>;


#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Bounds3<T> {
    pub p_min: Point3<T>,
    pub p_max: Point3<T>,
}

impl<T> Bounds3<T>
where
    T: Num + Bounded + PartialOrd + Copy,
{
    pub fn new() -> Self {
        Self {
            p_min: Point3::new(T::max_value(), T::max_value(), T::max_value()),
            p_max: Point3::new(T::min_value(), T::min_value(), T::min_value()),
        }
    }

    pub fn from_point(p: Point3<T>) -> Self {
        Self { p_min: p, p_max: p }
    }

    pub fn from_points(p1: Point3<T>, p2: Point3<T>) -> Self {
        Self {
            p_min: Point3::new(
                if p1.x < p2.x { p1.x } else { p2.x },
                if p1.y < p2.y { p1.y } else { p2.y },
                if p1.z < p2.z { p1.z } else { p2.z },
            ),
            p_max: Point3::new(
                if p1.x > p2.x { p1.x } else { p2.x },
                if p1.y > p2.y { p1.y } else { p2.y },
                if p1.z > p2.z { p1.z } else { p2.z },
            ),
        }
    }
    
    pub fn diagonal(&self) -> Vector3<T> {
        self.p_max - self.p_min
    }
    
    pub fn surface_area(&self) -> T {
        let d = self.diagonal();
        let two = T::one() + T::one();
        two * (d.x * d.y + d.x * d.z + d.y * d.z)
    }
    
    pub fn volume(&self) -> T {
        let d = self.diagonal();
        d.x * d.y * d.z
    }
    
    pub fn is_empty(&self) -> bool {
        self.p_min.x >= self.p_max.x || self.p_min.y >= self.p_max.y || self.p_min.z >= self.p_max.z
    }

    pub fn max_dimension(&self) -> usize {
        let d = self.diagonal();
        if d.x > d.y && d.x > d.z {
            return 0;
        } else if d.y > d.z {
            return 1;
        }
        2
    }
}

pub fn union_bounds<T: PartialOrd + Copy>(b1: Bounds3<T>, b2: Bounds3<T>) -> Bounds3<T> {
    Bounds3 {
        p_min: Point3::new(
            if b1.p_min.x < b2.p_min.x { b1.p_min.x } else { b2.p_min.x },
            if b1.p_min.y < b2.p_min.y { b1.p_min.y } else { b2.p_min.y },
            if b1.p_min.z < b2.p_min.z { b1.p_min.z } else { b2.p_min.z },
        ),
        p_max: Point3::new(
            if b1.p_max.x > b2.p_max.x { b1.p_max.x } else { b2.p_max.x },
            if b1.p_max.y > b2.p_max.y { b1.p_max.y } else { b2.p_max.y },
            if b1.p_max.z > b2.p_max.z { b1.p_max.z } else { b2.p_max.z },
        ),
    }
}

pub fn union_bounds_point<T: PartialOrd + Copy>(b: Bounds3<T>, p: Point3<T>) -> Bounds3<T> {
     Bounds3 {
        p_min: Point3::new(
            if b.p_min.x < p.x { b.p_min.x } else { p.x },
            if b.p_min.y < p.y { b.p_min.y } else { p.y },
            if b.p_min.z < p.z { b.p_min.z } else { p.z },
        ),
        p_max: Point3::new(
            if b.p_max.x > p.x { b.p_max.x } else { p.x },
            if b.p_max.y > p.y { b.p_max.y } else { p.y },
            if b.p_max.z > p.z { b.p_max.z } else { p.z },
        ),
    }
}