diff --git a/src/aabb.rs b/src/aabb.rs
index f012e03..7af0844 100644
--- a/src/aabb.rs
+++ b/src/aabb.rs
@@ -19,22 +19,11 @@ impl Default for Aabb {
     }
 }
 
-//impl Hittable for Aabb {
 impl Aabb {
     pub fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> bool {
         let mut t_min = t_min;
         let mut t_max = t_max;
         for a in 0..3 {
-            /*
-            let t0 = ((self.minimum[a] - ray.origin()[a]) / ray.direction()[a])
-                .min((self.maximum[a] - ray.origin()[a]) / ray.direction()[a]);
-            let t1 = ((self.minimum[a] - ray.origin()[a]) / ray.direction()[a])
-                .max((self.maximum[a] - ray.origin()[a]) / ray.direction()[a]);
-            t_min = t0.min(t_min);
-            t_max = t1.max(t_max);
-            if t_max <= t_min {
-                return false;
-            }*/
             let inv_d = 1.0 / ray.direction()[a];
             let mut t0 = (self.minimum[a] - ray.origin()[a]) * inv_d;
             let mut t1 = (self.maximum[a] - ray.origin()[a]) * inv_d;
diff --git a/src/bvh.rs b/src/bvh.rs
index 0d5a46b..cdf5c88 100644
--- a/src/bvh.rs
+++ b/src/bvh.rs
@@ -1,4 +1,4 @@
-use crate::hittable::{HittableList, Hittable, HitRecord};
+use crate::hittable::{HittableList, Hittable, HitRecord, HittableObject};
 use crate::aabb::Aabb;
 use std::cmp;
 use crate::Ray;
@@ -7,7 +7,7 @@ use crate::Ray;
 
 enum BVHNode {
     Branch { left: Box<BVH>, right: Box<BVH> },
-    Leaf(Box<dyn Hittable>)
+    Leaf(HittableObject)
 }
 
 pub struct BVH {
@@ -17,7 +17,7 @@ pub struct BVH {
 
 impl BVH {
     pub fn new(mut objects: HittableList, time0: f64, time1: f64) -> Self {
-        fn box_compare(time0: f64, time1: f64, axis: usize) -> impl FnMut(&Box<dyn Hittable + Sync>, &Box<dyn Hittable + Sync>) -> cmp::Ordering {
+        fn box_compare(time0: f64, time1: f64, axis: usize) -> impl FnMut(&HittableObject, &HittableObject) -> cmp::Ordering {
             move |a, b| {
                 let a_bbox = a.bounding_box(time0, time1);
                 let b_bbox = b.bounding_box(time0, time1);
@@ -90,7 +90,7 @@ impl Hittable for BVH {
             }
         }
     }
-    fn bounding_box(&self, time0: f64, time1: f64) -> Option<Aabb> {
+    fn bounding_box(&self, _time0: f64, _time1: f64) -> Option<Aabb> {
         Some(self.bounding_box)
     }
 }
diff --git a/src/hittable.rs b/src/hittable.rs
index f4e7c74..141be51 100644
--- a/src/hittable.rs
+++ b/src/hittable.rs
@@ -2,8 +2,10 @@ use crate::{Point3, Ray, Vec3};
 use crate::material::{Material};
 use crate::aabb::Aabb;
 use std::f64::consts::PI;
+use std::sync::Arc;
 
-pub type HittableList = Vec<Box<dyn Hittable + Sync>>;
+pub type HittableObject = Arc<dyn Hittable + Sync + Send>;
+pub type HittableList = Vec<HittableObject>;
 
 //#[derive(Debug, Clone, Copy)]
 #[derive(Clone, Copy)]
@@ -14,7 +16,7 @@ pub struct HitRecord<'material> {
     pub u: f64,
     pub v: f64,
     pub front_face: bool,
-    pub material: &'material Material
+    pub material: &'material Arc<Material>
 }
 
 pub trait Hittable {
@@ -26,10 +28,10 @@ pub trait Hittable {
 pub struct Sphere {
     pub center: Point3,
     pub radius: f64,
-    pub material: Material
+    pub material: Arc<Material>
 }
 impl Sphere {
-    pub fn new(center: Point3, radius: f64, material: Material) -> Sphere {
+    pub fn new(center: Point3, radius: f64, material: Arc<Material>) -> Sphere {
         Sphere { center, radius, material }
     }
     pub fn uv(point: &Point3) -> (f64, f64) {
@@ -51,7 +53,7 @@ impl Default for Sphere {
         Sphere {
             center: Point3::default(),
             radius: 0.0,
-            material: Material::default()
+            material: Arc::new(Material::default())
         }
     }
 }
@@ -100,7 +102,7 @@ pub struct MovableSphere {
     pub center0: Point3,
     pub center1: Point3,
     pub radius: f64,
-    pub material: Material,
+    pub material: Arc<Material>,
     pub time0: f64,
     pub time1: f64,
 }
@@ -109,7 +111,7 @@ impl MovableSphere {
         center0: Point3,
         center1: Point3,
         radius: f64,
-        material: Material,
+        material: Arc<Material>,
         time0: f64,
         time1: f64) -> Self {
         MovableSphere { center0, center1, radius, material, time0, time1 }
@@ -124,7 +126,7 @@ impl Default for MovableSphere {
             center0: Point3::default(),
             center1: Point3::default(),
             radius: 0.0,
-            material: Material::default(),
+            material: Arc::new(Material::default()),
             time0: 0.0,
             time1: 0.0
         }
diff --git a/src/main.rs b/src/main.rs
index 2b6b901..17b73fb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,8 @@
-use std::sync::Mutex;
+use std::sync::{Arc, Mutex};
 use std::time::Instant;
 
 use crate::camera::Camera;
-use crate::hittable::{Hittable, Sphere, HittableList};
+use crate::hittable::{Hittable, Sphere, HittableList, HittableObject};
 use crate::output::{Output, PNG};
 use crate::ray::Ray;
 use crate::vec3::{Color, Point3, Vec3};
@@ -25,20 +25,38 @@ mod aabb;
 mod bvh;
 mod texture;
 
-fn random_scene() -> HittableList {
+fn two_spheres() -> HittableList {
     let mut world:HittableList = Vec::new();
-
-    //let material_ground = Material::Lambertian(Lambertian::new(Color::new(0.5, 0.5, 0.5)));
     let checker = CheckerTexture::colored(
         Color::new(0.2, 0.3, 0.1),
         Color::new(0.9, 0.9, 0.9));
-    let material_ground = Material::Lambertian(Lambertian::textured(Box::new(checker)));
+    let checker_material = Arc::new(Material::Lambertian(Lambertian::textured(Arc::new(checker))));
+    world.push(Arc::new(Sphere {
+        center: Point3::new(0.0, -10.0, 0.0),
+        radius: 10.0,
+        material: Arc::clone(&checker_material)
+    }));
+    world.push(Arc::new(Sphere {
+        center: Point3::new(0.0, 10.0, 0.0),
+        radius: 10.0,
+        material: checker_material
+    }));
+    world
+}
+
+fn random_scene() -> HittableList {
+    let mut world: HittableList = Vec::new();
+
+    let checker = CheckerTexture::colored(
+        Color::new(0.2, 0.3, 0.1),
+        Color::new(0.9, 0.9, 0.9));
+    let material_ground = Arc::new(Material::Lambertian(Lambertian::textured(Arc::new(checker))));
     let ground = Sphere {
         center: Point3::new(0.0, -1000.0, 0.0),
         radius: 1000.0,
         material: material_ground
     };
-    world.push(Box::new(ground));
+    world.push(Arc::new(ground));
 
     let unit_range = Uniform::from(0.0..1.0);
     let fuzz_range = Uniform::from(0.0..0.5);
@@ -55,17 +73,17 @@ fn random_scene() -> HittableList {
                 continue;
             }
             let material = match choose_material {
-                _ if choose_material < 0.8 => Material::Lambertian(Lambertian::new(
-                    Color::random(0.0, 1.0) * Color::random(0.0, 1.0))),
-                _ if choose_material < 0.95 => Material::Metal(Metal::new(
+                _ if choose_material < 0.8 => Arc::new(Material::Lambertian(Lambertian::new(
+                    Color::random(0.0, 1.0) * Color::random(0.0, 1.0)))),
+                _ if choose_material < 0.95 => Arc::new(Material::Metal(Metal::new(
                     Color::random(0.5, 1.0),
-                    fuzz_range.sample(&mut rng))),
-                _ => Material::Dielectric(Dielectric::new(1.5)),
+                    fuzz_range.sample(&mut rng)))),
+                _ => Arc::new(Material::Dielectric(Dielectric::new(1.5))),
             };
-            let sphere: Box<dyn Hittable + Sync> = match rng.gen_bool(1.0 / 3.0) {
+            let sphere: HittableObject = match rng.gen_bool(1.0 / 3.0) {
                 true => {
                     let center1 = center + Vec3::new(0.0, fuzz_range.sample(&mut rng) / 2.0, 0.0);
-                    Box::new(MovableSphere {
+                    Arc::new(MovableSphere {
                         center0: center,
                         center1,
                         radius: 0.2,
@@ -74,7 +92,7 @@ fn random_scene() -> HittableList {
                         time1: 1.0
                     })
                 }
-                false => Box::new(Sphere {
+                false => Arc::new(Sphere {
                     center,
                     radius: 0.2,
                     material
@@ -84,20 +102,20 @@ fn random_scene() -> HittableList {
         }
     }
 
-    let material1 = Material::Dielectric(Dielectric::new(1.5));
-    world.push(Box::new(Sphere {
+    let material1 = Arc::new(Material::Dielectric(Dielectric::new(1.5)));
+    world.push(Arc::new(Sphere {
         center: Point3::new(0.0, 1.0, 0.0),
         radius: 1.0,
         material: material1
     }));
-    let material2 = Material::Lambertian(Lambertian::new(Color::new(0.4, 0.2, 0.1)));
-    world.push(Box::new(Sphere {
+    let material2 = Arc::new(Material::Lambertian(Lambertian::new(Color::new(0.4, 0.2, 0.1))));
+    world.push(Arc::new(Sphere {
         center: Point3::new(-4.0, 1.0, 0.0),
         radius: 1.0,
         material: material2
     }));
-    let material3 = Material::Metal(Metal::new(Color::new(0.7, 0.6, 0.5), 0.0));
-    world.push(Box::new(Sphere {
+    let material3 = Arc::new(Material::Metal(Metal::new(Color::new(0.7, 0.6, 0.5), 0.0)));
+    world.push(Arc::new(Sphere {
         center: Point3::new(4.0, 1.0, 0.0),
         radius: 1.0,
         material: material3
@@ -117,20 +135,25 @@ fn main() {
     let look_from = Point3::new(13.0, 2.0, 3.0);
     let look_at = Point3::new(0.0, 0.0, 0.0);
     let focus_dist = 10.0;
+
     // Camera
     let cam = Camera::new(
         look_from,
         look_at,
         Vec3::new(0.0, 1.0, 0.0),
         ASPECT_RATIO,
-        20.0,
-        0.1,
+        40.0,
+        0.0,
         focus_dist,
     0.0,
     1.0);
 
     // World
-    let world= random_scene();
+    let scene: u8 = 0;
+    let world = match scene {
+        0 => two_spheres(),
+        _ => random_scene()
+    };
 
     let between = Uniform::from(0.0..1.0);
 
diff --git a/src/material.rs b/src/material.rs
index 14f7425..13c3af1 100644
--- a/src/material.rs
+++ b/src/material.rs
@@ -1,3 +1,5 @@
+use std::rc::Rc;
+use std::sync::Arc;
 use rand::Rng;
 use crate::hittable::HitRecord;
 use crate::{Color, Ray, Vec3};
@@ -7,7 +9,6 @@ pub trait Scatterable {
     fn scatter(&self, ray: &Ray, hit_record: &HitRecord) -> Option<(Option<Ray>, Color)>;
 }
 
-//#[derive(Debug, Clone)]
 pub enum Material {
     Lambertian(Lambertian),
     Metal(Metal),
@@ -30,16 +31,15 @@ impl Scatterable for Material {
     }
 }
 
-//#[derive(Debug, Clone)]
 pub struct Lambertian {
-    pub albedo: Box<dyn Texture>
+    pub albedo: Arc<dyn Texture>
 }
 impl Lambertian {
     pub fn new(albedo: Color) -> Self {
         let texture = SolidColor::from(albedo);
-        Lambertian { albedo: Box::new(texture) }
+        Lambertian { albedo: Arc::new(texture) }
     }
-    pub fn textured(albedo: Box<dyn Texture>) -> Self {
+    pub fn textured(albedo: Arc<dyn Texture>) -> Self {
         Lambertian { albedo }
     }
 }
diff --git a/src/texture.rs b/src/texture.rs
index 9f67d75..523926b 100644
--- a/src/texture.rs
+++ b/src/texture.rs
@@ -1,6 +1,6 @@
 use crate::{Point3, Color};
 
-pub trait Texture: Sync {
+pub trait Texture: Sync + Send {
     fn value(&self, u: f64, v: f64, point: &Point3) -> Color;
 }
 
@@ -45,9 +45,9 @@ impl CheckerTexture {
 
 impl Texture for CheckerTexture {
     fn value(&self, u: f64, v: f64, point: &Point3) -> Color {
-        let sines = (10.0 * point.x().sin()) *
-            (10.0 * point.y().sin()) *
-            (10.0 * point.z().sin());
+        let sines = (10.0 * point.x()).sin() *
+            (10.0 * point.y()).sin() *
+            (10.0 * point.z()).sin();
         match sines {
             sines if sines < 0.0 => self.odd.value(u, v, point),
             _ => self.even.value(u, v, point),