Material references... but bad ordering

It looks like I messed up the preference for the HitRecords. The
geometry bounces correctly, but the record that sticks is not
necessarily the one closest to the camera.

src/main.rs

@@ -134,7 +134,7 @@ fn random_scene(srng: &mut SmallRng) -> Hittable {
     let mat_ground = Material::Lambertian { albedo: Vec3::new(0.5, 0.5, 0.5) };
     let mut world = Hittable::HittableList { hittables : Vec::<Hittable>::new() };
     
-    world.push( Hittable::Sphere { center: Vec3::new(0.0, -1000.0, 0.0), radius: 1000.0, material: Some(mat_ground) });
+    world.push( Hittable::Sphere { center: Vec3::new(0.0, -1000.0, 0.0), radius: 1000.0, material: mat_ground });
     
     let distrib_zero_one = Uniform::new(0.0, 1.0);
     for a in -11..11 {
@@ -155,7 +155,7 @@ fn random_scene(srng: &mut SmallRng) -> Hittable {
                         Hittable::Sphere {
                             center,
                             radius: 0.2,
-                            material: Some(sphere_material),
+                            material: sphere_material,
                         }
                     );
                 } else if choose_mat < 0.95 {
@@ -170,7 +170,7 @@ fn random_scene(srng: &mut SmallRng) -> Hittable {
                         Hittable::Sphere {
                             center,
                             radius: 0.2,
-                            material: Some(material),
+                            material: material,
                         }
                     );
                 } else {
@@ -180,7 +180,7 @@ fn random_scene(srng: &mut SmallRng) -> Hittable {
                         Hittable::Sphere{
                             center,
                             radius: 0.2,
-                            material: Some(material),
+                            material: material,
                         }
                     );
 
@@ -193,21 +193,21 @@ fn random_scene(srng: &mut SmallRng) -> Hittable {
     world.push( Hittable::Sphere{
         center: Vec3::new(0.0, 1.0, 0.0),
         radius: 1.0,
-        material: Some(material1)
+        material: material1
     });
 
     let material2 = Material::Lambertian { albedo: Vec3::new(0.4, 0.2, 0.1) };
     world.push( Hittable::Sphere {
         center: Vec3::new(-4.0, 1.0, 0.0),
         radius: 1.0,
-        material: Some(material2)
+        material: material2
     });
 
     let material3 = Material::Metal { albedo: Vec3::new(0.7, 0.6, 0.5), fuzz: 0.0 };
     world.push( Hittable::Sphere {
         center: Vec3::new(4.0, 1.0, 0.0),
         radius: 1.0,
-        material: Some(material3)
+        material: material3
     });
 
     return world;

src/renderer.rs

@@ -65,14 +65,9 @@ fn ray_color(r: Ray, world: &Hittable, depth: u32, srng: &mut SmallRng, distrib:
             dir: Vec3::zero()
         };
         let mut attenuation = Vec3::zero();
-        match rec.material {
-            Some(mat) => {
-                if mat.scatter(r, rec, &mut attenuation, &mut scattered, srng) {
-                    return attenuation * ray_color(scattered, world, depth-1, srng, distrib);
-                };
-            },
-            None => return Vec3::zero(),
-        }
+        if rec.material.scatter(r, &rec, &mut attenuation, &mut scattered, srng) {
+            return attenuation * ray_color(scattered, world, depth-1, srng, distrib);
+        };
     }
 
     let unitdir = Vec3::as_unit(r.dir);

src/scene.rs

@@ -8,7 +8,7 @@ use rand::distributions::Uniform;
 pub struct HitRecord{
     pub p: Vec3,
     pub normal: Vec3,
-    pub material: Option<Material>,
+    pub material: Material,
     pub t: f32,
     pub front_face: bool,
 }
@@ -22,7 +22,7 @@ impl HitRecord{
 
 #[derive (Clone)]
 pub enum Hittable {
-    Sphere { center: Vec3, radius: f32, material: Option<Material> },
+    Sphere { center: Vec3, radius: f32, material: Material },
     HittableList { hittables: Vec<Hittable> }
 }
 
@@ -30,23 +30,17 @@ impl Hittable {
     pub fn hit(&self, r: Ray, t_min: f32, t_max: f32) -> Option<HitRecord> {
         match self {
             Hittable::HittableList { hittables } => {
-                let mut might_return = HitRecord {
-                    p: Vec3::zero(),
-                    normal: Vec3::zero(),
-                    material: None,
-                    t: t_max,
-                    front_face: false,
-                };
+                let mut might_return: Option<HitRecord> = None;
                 let mut hit_anything = false;
 
                 for item in hittables {
-                    if let Some(record) = item.hit(r, t_min, might_return.t){
+                    if let Some(record) = item.hit(r, t_min, t_max){
                         hit_anything = true;
-                        might_return = record;
+                        might_return = Some(record);
                     }
                 }
                 if hit_anything{
-                    return Some(might_return);
+                    return might_return;
                 } else { return None; }
             }
 
@@ -102,7 +96,7 @@ impl Material {
     pub fn scatter(
         &self,
         ray_in: Ray,
-        rec: HitRecord,
+        rec: &HitRecord,
         attenuation: &mut Vec3,
         scattered: &mut Ray,
         srng: &mut SmallRng,