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use std::option::Option;
use std::sync::Arc;
use crate::geometry::{HitRecord, Hittable};
use crate::material::Material;
use crate::ray::Ray;
use crate::vec3::Vec3;
pub struct Sphere {
pos: Vec3,
radius: f64,
material: Arc<Box<dyn Material>>,
}
impl Sphere {
pub fn new(pos: Vec3, radius: f64, material: Arc<Box<dyn Material>>) -> Self {
Self {
pos,
radius,
material,
}
}
}
impl Hittable for Sphere {
fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
let oc = ray.origin() - self.pos;
let a = ray.direction().length_squared();
let half_b = oc.dot(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 sqrtd = discriminant.sqrt();
// Find the nearest root that lies in acceptable range.
let mut root = (-half_b - sqrtd) / a;
if root < t_min || t_max < root {
root = (-half_b + sqrtd) / a;
if root < t_min || t_max < root {
return None;
}
}
let point = ray.at(root);
let outward_normal = (point - self.pos) / self.radius;
let mut hit_record = HitRecord::new(point, root, Arc::clone(&self.material));
hit_record.set_face_normal(ray, outward_normal);
Some(hit_record)
}
}
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