diff --git a/output.png b/output.png
index fdbd692..8cca54b 100644
Binary files a/output.png and b/output.png differ
diff --git a/src/main.rs b/src/main.rs
index a28a657..713cd85 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,16 +1,40 @@
 #![feature(core_float_math)]
 
+mod objects;
 mod ray;
 mod vec3;
 
+use core::f32;
 use std::cmp::max;
 
+use crate::objects::hit::Hit;
+use crate::objects::sphere::Sphere;
+use crate::objects::traits::{Hittable, Normal};
 use crate::ray::Ray;
 use crate::vec3::{Colour, Vec3};
 use log::info;
 use pretty_env_logger;
 
-fn ray_colour(r: &Ray) -> Colour {
+fn ray_colour<T>(hittables: &Vec<T>, r: &Ray) -> Colour
+where
+    T: Hittable + Normal,
+{
+    let mut closest: Option<Hit> = None;
+    for hittable in hittables {
+        if let Some(hit) = hittable.hit(r) {
+            // hit happens in front of camera and is closer than closest
+            if *hit.t() > 0. && (closest.is_none() || closest.as_ref().unwrap().t() > hit.t()) {
+                closest = Some(hit);
+            }
+        }
+    }
+
+    if let Some(hit) = closest {
+        let n = hit.n();
+        return 0.5 * Colour::new(n.x() + 1., n.y() + 1., n.z() + 1.);
+    }
+
+    // background
     let unit_dir = r.dir().get_unit();
     let a = 0.5 * (unit_dir.y() + 1.);
 
@@ -19,8 +43,8 @@ fn ray_colour(r: &Ray) -> Colour {
 
 fn main() {
     // use structs so rust-analyzer can provide lsp
-    let v = Vec3::new(255., 0., 255.);
-    let _ = Ray::new(v.clone(), v.clone());
+    let s = Sphere::new(Vec3::new(0., 0., -1.), 0.5);
+    let objects = vec![s];
 
     pretty_env_logger::init();
 
@@ -56,7 +80,7 @@ fn main() {
             let r = Ray::new(camera_center, ray_dir);
 
             let pixel = imgbuf.get_pixel_mut(i, j);
-            *pixel = ray_colour(&r).output();
+            *pixel = ray_colour(&objects, &r).output();
         }
     }
 
diff --git a/src/objects.rs b/src/objects.rs
new file mode 100644
index 0000000..b7c1286
--- /dev/null
+++ b/src/objects.rs
@@ -0,0 +1,3 @@
+pub mod hit;
+pub mod sphere;
+pub mod traits;
diff --git a/src/objects/hit.rs b/src/objects/hit.rs
new file mode 100644
index 0000000..e801ec7
--- /dev/null
+++ b/src/objects/hit.rs
@@ -0,0 +1,25 @@
+use crate::vec3::Vec3;
+
+pub struct Hit {
+    t: f32,
+    p: Vec3,
+    n: Vec3,
+}
+
+impl Hit {
+    pub fn new(t: f32, p: Vec3, n: Vec3) -> Hit {
+        Hit { t: t, p: p, n: n }
+    }
+
+    pub fn t(&self) -> &f32 {
+        &self.t
+    }
+
+    pub fn p(&self) -> &Vec3 {
+        &self.p
+    }
+
+    pub fn n(&self) -> &Vec3 {
+        &self.n
+    }
+}
diff --git a/src/objects/sphere.rs b/src/objects/sphere.rs
new file mode 100644
index 0000000..79f464a
--- /dev/null
+++ b/src/objects/sphere.rs
@@ -0,0 +1,44 @@
+use core::f32::math::sqrt;
+
+use crate::objects::hit::Hit;
+use crate::objects::traits::{Hittable, Normal};
+use crate::Vec3;
+
+pub struct Sphere {
+    center: Vec3,
+    radius: f32,
+}
+
+impl Sphere {
+    pub fn new(center: Vec3, radius: f32) -> Sphere {
+        Sphere {
+            center: center,
+            radius: radius,
+        }
+    }
+}
+
+impl Hittable for Sphere {
+    fn hit(&self, r: &crate::ray::Ray) -> Option<Hit> {
+        let oc = self.center - r.origin();
+        let a = r.dir().dot(r.dir());
+        let b = -2. * r.dir().dot(&oc);
+        let c = oc.dot(&oc) - self.radius * self.radius;
+
+        let d = b * b - 4. * a * c;
+
+        if d < 0. {
+            None
+        } else {
+            let t = (-b - sqrt(d)) / (2.0 * a);
+            let p = r.at(t);
+            Some(Hit::new(t, p, self.normal_at(&p)))
+        }
+    }
+}
+
+impl Normal for Sphere {
+    fn normal_at(&self, p: &Vec3) -> Vec3 {
+        (*p - self.center).get_unit()
+    }
+}
diff --git a/src/objects/traits.rs b/src/objects/traits.rs
new file mode 100644
index 0000000..48d571e
--- /dev/null
+++ b/src/objects/traits.rs
@@ -0,0 +1,11 @@
+use crate::objects::hit::Hit;
+use crate::Ray;
+use crate::Vec3;
+
+pub trait Hittable {
+    fn hit(&self, r: &Ray) -> Option<Hit>;
+}
+
+pub trait Normal {
+    fn normal_at(&self, p: &Vec3) -> Vec3;
+}
diff --git a/src/ray.rs b/src/ray.rs
index db8475a..80f23da 100644
--- a/src/ray.rs
+++ b/src/ray.rs
@@ -6,7 +6,7 @@ pub struct Ray {
 }
 
 impl Ray {
-    pub fn at(self, t: f32) -> Vec3 {
+    pub fn at(&self, t: f32) -> Vec3 {
         self.origin + t * self.dir
     }
 
diff --git a/src/vec3.rs b/src/vec3.rs
index 3ba2014..f67018d 100644
--- a/src/vec3.rs
+++ b/src/vec3.rs
@@ -46,15 +46,11 @@ impl Vec3 {
         (self.r * self.r + self.g * self.g + self.b * self.b) as f32
     }
 
-    pub fn dot(self, other: Vec3) -> Vec3 {
-        Vec3 {
-            r: self.r * other.r,
-            g: self.g * other.g,
-            b: self.b * other.b,
-        }
+    pub fn dot(&self, other: &Vec3) -> f32 {
+        self.r * other.r + self.g * other.g + self.b * other.b
     }
 
-    pub fn cross(self, other: Vec3) -> Vec3 {
+    pub fn cross(&self, other: &Vec3) -> Vec3 {
         Vec3 {
             r: self.g * other.b - self.b * other.g,
             g: self.b * other.r - self.r * other.b,
@@ -142,6 +138,17 @@ impl AddAssign<f32> for Vec3 {
         };
     }
 }
+impl Sub<&Vec3> for Vec3 {
+    type Output = Self;
+
+    fn sub(self, rhs: &Self) -> Self {
+        Self {
+            r: self.r - rhs.r,
+            g: self.g - rhs.g,
+            b: self.b - rhs.b,
+        }
+    }
+}
 
 impl Sub<Vec3> for Vec3 {
     type Output = Self;