Fix hit determination inside a sphere

.gitignore

@@ -2,3 +2,4 @@
 *.ppm
 .idea
 *.iml
+.vscode/

src/hittable.rs

@@ -42,16 +42,16 @@ impl Hittable for Sphere {
         let discriminant = half_b * half_b - a * c;
         if discriminant < 0.0 { return None; }
 
-        let sqrtd = f64::sqrt(discriminant);
+        let sqrtd = discriminant.sqrt();
-        let root = (-half_b - sqrtd) / a;
+        let mut root = (-half_b - sqrtd) / a;
         if root < t_min || t_max < root {
-            let root = (-half_b + sqrtd) / a;
+            root = (-half_b + sqrtd) / a;
             if root < t_min || t_max < root { return None; }
         }
-
         let point = ray.at(root);
         let normal = (point - self.center) / self.radius;
-        let front_face = ray.direction().dot(&normal) < 0.0;
+        let dot = ray.direction().dot(&normal);
+        let front_face = dot < 0.0;
         let normal = if front_face { normal } else { -normal };
         Some(HitRecord {
             point,

src/material.rs

@@ -104,6 +104,7 @@ impl Scatterable for Dielectric {
             self.index_of_refraction
         };
         let unit_direction = ray.direction().unit_vector();
+
         let cos_theta = ((-unit_direction).dot(&hit_record.normal)).min(1.0);
         let sin_theta = (1.0 - cos_theta*cos_theta).sqrt();
         let cannot_refract = refraction_ratio * sin_theta > 1.0;
@@ -112,12 +113,10 @@ impl Scatterable for Dielectric {
 
         if cannot_refract || reflectance > rng.gen::<f64>() {
             let reflected = unit_direction.reflected(&hit_record.normal);
-            let reflected = Vec3::new(-reflected.x(), reflected.y(), -reflected.z());
             let scattered = Ray::new(hit_record.point, reflected);
             Some((Some(scattered), color))
         } else {
-            //let direction = unit_direction.refract(&hit_record.normal, refraction_ratio);
+            let direction = unit_direction.refract(&hit_record.normal, refraction_ratio);
-            let direction = unit_direction.refract_sort_of_works(&hit_record.normal, refraction_ratio);
             let scattered = Ray::new(hit_record.point, direction);
             Some((Some(scattered), color))
         }

src/ray.rs

@@ -3,6 +3,7 @@ use crate::hittable::HitRecord;
 use crate::material::Scatterable;
 use crate::vec3::Point3;
 
+#[derive(Debug)]
 pub struct Ray {
     origin: Point3,
     direction: Vec3

src/vec3.rs

@@ -84,21 +84,6 @@ impl Vec3 {
         let out_parallel = r * (*normal);
         out_perp + out_parallel
     }
-    pub fn refract_sort_of_works(&self, normal: &Vec3, etai_over_etat: f64) -> Vec3 {
-        let dot = (-(*self)).dot(normal);
-        let cos_theta = dot.min(1.0);
-        let out_perp = etai_over_etat * ((*self) + cos_theta * (*normal));
-        let inner =  1.0 - out_perp.length_squared();
-        let abs = inner.abs();
-        let r = -(abs.sqrt());
-        let out_parallel = r * (*normal);
-        // Why?
-        let mut res = out_perp + out_parallel;
-        res.x = -res.x;
-        //res.y = -res.y;
-        res.z = -res.z;
-        res
-    }
 }
 
 #[test]