3 files changed, 66 insertions(+), 0 deletions(-)

A src/hittable.rs
M src/main.rs
A src/sphere.rs

@@ 0,0 1,13 @@
+use crate::vec3::*;
+use crate::ray::*;
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct HitRecord {
+    pub p: Point3,
+    pub normal: Vec3,
+    pub t: f64,
+}
+
+pub trait Hittable {
+    fn hit(&self, r: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord>;
+}

@@ 4,6 4,12 @@ use vec3::*;
 mod ray;
 use ray::*;
 
+mod hittable;
+use hittable::*;
+
+mod sphere;
+use sphere::*;
+
 fn hit_sphere(center: &Point3, radius: f64, r: &Ray) -> f64 {
     let oc = r.origin() - *center;
     let a = r.direction().length_squared();

@@ 0,0 1,47 @@
+use crate::vec3::*;
+use crate::ray::*;
+use crate::hittable::*;
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Sphere {
+    center: Point3,
+    radius: f64,
+}
+
+impl Sphere {
+    fn new(center: Point3, radius: f64) -> Self {
+        Self{center, radius}
+    }
+}
+
+impl Hittable for Sphere {
+    fn hit(&self, r: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
+        let oc = r.origin() - self.center;
+        let a = r.direction().length_squared();
+        let half_b = dot(&oc, &r.direction());
+        let c = oc.length_squared() - self.radius*self.radius;
+        let discriminant = half_b*half_b - a*c;
+
+        if discriminant > 0.0 {
+            let root = discriminant.sqrt();
+
+            let temp = (-half_b - root) / a;
+            if temp < t_max && temp > t_min {
+                let t = temp;
+                let p = r.at(t);
+                let normal = (p - self.center) / self.radius;
+                return Some(HitRecord{t, p, normal})
+            }
+
+            let temp = (-half_b + root) / a;
+            if temp < t_max && temp > t_min {
+                let t = temp;
+                let p = r.at(t);
+                let normal = (p - self.center) / self.radius;
+                return Some(HitRecord{t, p, normal})
+            }
+        }
+
+        return None;
+    }
+}