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use crate::{
    materials::Material,
    math::{Point3, Ray, Vector3},
};

pub struct HitRecord<'a> {
    pub point: Point3,
    pub normal: Vector3,
    pub t: f64,
    pub front_face: bool,
    pub material: &'a Box<dyn Material>,
}

impl<'a> HitRecord<'a> {
    pub fn new(
        point: Point3,
        normal: Vector3,
        t: f64,
        front_face: bool,
        material: &'a Box<dyn Material>,
    ) -> Self {
        Self {
            point,
            normal,
            t,
            front_face,
            material,
        }
    }

    pub fn set_face_normal(&mut self, ray: Ray, outward_normal: Vector3) {
        self.front_face = Vector3::dot(&ray.direction, &outward_normal) < 0.0;
        self.normal = if self.front_face {
            outward_normal
        } else {
            -outward_normal
        };
    }
}

pub trait Hittable {
    fn hit(&self, ray: Ray, t_min: f64, t_max: f64) -> Option<HitRecord>;
}

pub struct Sphere {
    pub center: Point3,
    pub radius: f64,
    pub material: Box<dyn Material>,
}

impl Sphere {
    pub fn new(center: Point3, radius: f64, material: Box<dyn Material>) -> Self {
        Self {
            center,
            radius,
            material,
        }
    }
}

impl Hittable for Sphere {
    fn hit(&self, ray: Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
        let oc = ray.origin - self.center;
        let a = ray.direction.length_squared();
        let half_b = Vector3::dot(&oc, &ray.direction);
        let c = oc.length_squared() - self.radius * self.radius;

        let discriminant = half_b * half_b - a * c;

        if discriminant < 0.0 {
            return None;
        }

        let sqrt_discriminant = discriminant.sqrt();

        // Find the nearest root that lies in the acceptable range.
        let mut root = (-half_b - sqrt_discriminant) / a;
        if root < t_min || t_max < root {
            root = (-half_b + sqrt_discriminant) / a;
            if root < t_min || t_max < root {
                return None;
            }
        }

        let mut hit_record = HitRecord::new(
            ray.at(root),
            Vector3::new(0.0, 0.0, 0.0),
            root,
            false,
            &self.material,
        );

        let outward_normal = (hit_record.point - self.center) / self.radius;
        hit_record.set_face_normal(ray, outward_normal);

        Some(hit_record)
    }
}

pub struct HittableList {
    pub objects: Vec<Box<dyn Hittable>>,
}

impl HittableList {
    pub fn new() -> Self {
        Self { objects: vec![] }
    }

    pub fn add(&mut self, object: Box<dyn Hittable>) {
        self.objects.push(object);
    }

    pub fn clear(&mut self) {
        self.objects.clear();
    }

    pub fn hit(&self, ray: Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
        let mut hit_anything = None;
        let mut closest_so_far = t_max;

        for object in &self.objects {
            if let Some(hit_record) = object.hit(ray, t_min, closest_so_far) {
                closest_so_far = hit_record.t;
                hit_anything = Some(hit_record);
            }
        }

        hit_anything
    }
}