diff --git a/src/camera.h b/src/camera.h
index 79c1fad..ca1baca 100644
--- a/src/camera.h
+++ b/src/camera.h
@@ -1,19 +1,14 @@
 #pragma once
 
-#include <iostream>
-
-#include "image.h"
-#include "ray.h"
 #include "raytracer.h"
-#include "renderobject.h"
 #include "vec3.h"
 
 class Camera {
    public:
-    constexpr Camera(Vec3 centre, u32 image_width, u32 image_height, double focal_length)
-        : centre_{centre} {
-        constexpr double viewport_height = 2.0;
-        double viewport_width = viewport_height * static_cast<double>(image_width) / image_height;
+    constexpr Camera(Vec3 centre, u32 image_width, u32 image_height, f64 focal_length)
+        : centre_{centre}, image_width_{image_width}, image_height_{image_height} {
+        constexpr f64 viewport_height = 2.0;
+        f64 viewport_width = viewport_height * static_cast<f64>(image_width) / image_height;
 
         Vec3 u_viewport = viewport_width * Vec3::e_x;
         Vec3 v_viewport = -viewport_height * Vec3::e_y;
@@ -31,31 +26,17 @@ class Camera {
 
     constexpr Vec3 centre() const { return centre_; }
 
-    constexpr void Render(Image& img, const RenderObject& world) const {
-        for (u32 j = 0; j < img.height(); j++) {
-            std::clog << "\rWriting line " << j << " of " << img.height() << std::flush;
+    constexpr Vec3 d_u_pixel() const { return d_u_pixel_; }
+    constexpr Vec3 d_v_pixel() const { return d_v_pixel_; }
 
-            for (u32 i = 0; i < img.width(); i++) {
-                auto ray = CastRay(i, j);
+    constexpr u32 image_width() const { return image_width_; }
+    constexpr u32 image_height() const { return image_height_; }
 
-                img[i, j] = Cast(ray, world);
-            }
-        }
-    }
-
-   private:
-    constexpr Vec3 Image2World(u32 i, u32 j) const {
+    constexpr Vec3 PixelToWorld(u32 i, u32 j) const {
         return pixel_00_ + i * d_u_pixel_ + j * d_v_pixel_;
     }
 
-    constexpr Ray CastRay(u32 i, u32 j) const {
-        auto pixel_centre = Image2World(i, j);
-
-        auto ray_direction = pixel_centre - centre();
-
-        return Ray{centre(), ray_direction};
-    }
-
+   private:
     Vec3 centre_;
 
     // position of pixel 0, 0
@@ -64,4 +45,7 @@ class Camera {
     // Vec3 pointing from pixel to right/lower neighbour resp.
     Vec3 d_u_pixel_;
     Vec3 d_v_pixel_;
+
+    u32 image_width_;
+    u32 image_height_;
 };
diff --git a/src/colour.h b/src/colour.h
index 40f034a..47d57ee 100644
--- a/src/colour.h
+++ b/src/colour.h
@@ -17,21 +17,31 @@ class Colour {
     static const Colour kWhite;
 
     constexpr Colour() = default;
-    constexpr Colour(double r, double g, double b) : r_{r}, g_{g}, b_{b} {
-        assert(0.0 <= r && r <= 1.0);
-        assert(0.0 <= g && g <= 1.0);
-        assert(0.0 <= b && b <= 1.0);
+    constexpr Colour(f64 r, f64 g, f64 b) : r_{r}, g_{g}, b_{b} {}
+
+    constexpr void CheckValid() const {
+        assert(0.0 <= r() && r() <= 1.0);
+        assert(0.0 <= g() && g() <= 1.0);
+        assert(0.0 <= b() && b() <= 1.0);
     }
 
     constexpr explicit Colour(Vec3 v) : Colour{v.x(), v.y(), v.z()} {}
 
-    constexpr double& r() { return r_; }
-    constexpr double& g() { return g_; }
-    constexpr double& b() { return b_; }
+    constexpr f64& r() { return r_; }
+    constexpr f64& g() { return g_; }
+    constexpr f64& b() { return b_; }
 
-    constexpr double r() const { return r_; }
-    constexpr double g() const { return g_; }
-    constexpr double b() const { return b_; }
+    constexpr f64 r() const { return r_; }
+    constexpr f64 g() const { return g_; }
+    constexpr f64 b() const { return b_; }
+
+    constexpr Colour& operator+=(const Colour& c) {
+        r_ += c.r();
+        g_ += c.g();
+        b_ += c.b();
+
+        return *this;
+    }
 
     std::string to_string() const {
         std::stringstream ss;
@@ -46,17 +56,22 @@ class Colour {
     }
 
    private:
-    double r_;
-    double g_;
-    double b_;
+    f64 r_ = 0.0;
+    f64 g_ = 0.0;
+    f64 b_ = 0.0;
 };
 
 constexpr Colour Colour::kBlack{0.0, 0.0, 0.0};
 
-constexpr Colour operator*(double t, Colour col) { return {t * col.r(), t * col.g(), t * col.b()}; }
+constexpr Colour operator*(f64 t, Colour col) { return {t * col.r(), t * col.g(), t * col.b()}; }
+constexpr Colour operator/(Colour col, f64 t) { return (1.0 / t) * col; }
 
 constexpr Colour operator+(Colour c1, Colour c2) {
-    return {c1.r() + c2.r(), c1.g() + c2.g(), c1.b() + c2.b()};
+    Colour out{c1};
+
+    out += c2;
+
+    return out;
 }
 
 inline std::ostream& operator<<(std::ostream& os, Colour colour) {
diff --git a/src/image.h b/src/image.h
index 8f881ed..39a4e92 100644
--- a/src/image.h
+++ b/src/image.h
@@ -57,6 +57,8 @@ constexpr std::ostream& operator<<(std::ostream& os, const Image& img) {
         for (u32 i = 0; i < img.width(); i++) {
             const Colour col = img[i, j];
 
+            col.CheckValid();
+
             os << col << newline;
         }
     }
diff --git a/src/interval.h b/src/interval.h
index a2d0dfa..8351caa 100644
--- a/src/interval.h
+++ b/src/interval.h
@@ -1,22 +1,26 @@
 #pragma once
 
+#include <algorithm>
+
 #include "raytracer.h"
 class Interval {
    public:
     static const Interval kEmpty, kFull, kPositive;
 
     constexpr Interval() = default;
-    constexpr Interval(double min, double max) : min_{min}, max_{max} {}
+    constexpr Interval(f64 min, f64 max) : min_{min}, max_{max} {}
 
-    constexpr double min() const { return min_; }
-    constexpr double max() const { return max_; }
+    constexpr f64 min() const { return min_; }
+    constexpr f64 max() const { return max_; }
 
-    constexpr bool contains(double x) const { return min_ <= x && x <= max_; }
-    constexpr bool surronds(double x) const { return min_ < x && x < max_; }
+    constexpr bool contains(f64 x) const { return min_ <= x && x <= max_; }
+    constexpr bool surronds(f64 x) const { return min_ < x && x < max_; }
+
+    constexpr double clamp(f64 x) const { return std::clamp(x, min_, max_); }
 
    private:
-    double min_ = kInf;
-    double max_ = -kInf;
+    f64 min_ = kInf;
+    f64 max_ = -kInf;
 };
 
 constexpr Interval Interval::kEmpty{kInf, -kInf};
diff --git a/src/main.cc b/src/main.cc
index 26e5699..9eecf53 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -4,42 +4,43 @@
 #include "camera.h"
 #include "image.h"
 #include "raytracer.h"
+#include "renderer.h"
 #include "renderobject.h"
 #include "renderobjectlist.h"
 #include "sphere.h"
 #include "vec3.h"
 
 int main(int /* argc */, char* /* argv */[]) {
-    // image
-
-    constexpr double aspect_ratio = 16.0 / 9.0;
-
-    constexpr u32 image_width = 800;
-
-    constexpr auto image_height = static_cast<u32>(image_width / aspect_ratio);
-
-    static_assert(image_height >= 1);
-
-    Image img{image_width, image_height};
-
     // world
 
     RenderObjectList world;
 
-    world.Add(std::make_shared<Sphere>(Vec3{0, -100.5, -1}, 100));
+    // world.Add(std::make_shared<Sphere>(Vec3{0, -100.5, -1}, 100));
     world.Add(std::make_shared<Sphere>(-Vec3::e_z, 0.5));
 
     // camera
 
-    constexpr double focal_length = 1.0;
+    // constexpr f64 aspect_ratio = 16.0 / 9.0;
+
+    // constexpr u32 image_width = 800;
+    // constexpr auto image_height = static_cast<u32>(image_width / aspect_ratio);
+
+    constexpr u32 image_width = 1920;
+    constexpr u32 image_height = 1080;
+
+    static_assert(image_height >= 1);
+
+    constexpr f64 focal_length = 1.0;
 
     constexpr Point3 camera_centre{0.0, 0.0, 0.0};
 
-    Camera camera{camera_centre, img.width(), img.height(), focal_length};
+    Camera camera{camera_centre, image_width, image_height, focal_length};
 
     // render
 
-    camera.Render(img, world);
+    Renderer renderer{camera};
+
+    auto img = renderer.Render(world);
 
     std::cout << img;
 
diff --git a/src/rand.h b/src/rand.h
new file mode 100644
index 0000000..9144fe8
--- /dev/null
+++ b/src/rand.h
@@ -0,0 +1,47 @@
+#pragma once
+
+#include <cassert>
+
+#include "raytracer.h"
+class Random {
+   public:
+    constexpr explicit Random(u64 j) {
+        assert(j != v_);
+
+        u_ = j ^ v_;
+        GenU64();
+
+        v_ = u_;
+        GenU64();
+
+        w_ = v_;
+        GenU64();
+    }
+
+    constexpr u64 GenU64() {
+        u_ = u_ * 2862933555777941757ULL + 7046029254386353087ULL;
+
+        v_ ^= v_ >> 17;
+        v_ ^= v_ << 31;
+        v_ ^= v_ >> 8;
+
+        w_ = 4294957665ULL * (w_ & 0xffffffffULL) + (w_ >> 32);
+
+        u64 x = u_ ^ (u_ << 21);
+        x ^= x >> 35;
+        x ^= x << 4;
+
+        return (x + v_) ^ w_;
+    }
+
+    constexpr u32 GenU32() { return static_cast<u32>(GenU64()); }
+
+    constexpr f64 GenF64() { return 5.42101086242752217E-20 * static_cast<f64>(GenU64()); }
+
+    constexpr f64 GenF64(f64 min, f64 max) { return min + (max - min) * GenF64(); }
+
+   private:
+    u64 u_ = 0ULL;
+    u64 v_ = 4101842887655102017ULL;
+    u64 w_ = 1ULL;
+};
diff --git a/src/ray.h b/src/ray.h
index aee83c3..67f7eb7 100644
--- a/src/ray.h
+++ b/src/ray.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "raytracer.h"
 #include "vec3.h"
 
 class Ray {
@@ -11,7 +12,7 @@ class Ray {
     Point3 origin() const { return orig_; }
     Vec3 direction() const { return dir_; }
 
-    constexpr Point3 At(double t) const { return orig_ + t * dir_; }
+    constexpr Point3 At(f64 t) const { return orig_ + t * dir_; }
 
    private:
     Point3 orig_;
diff --git a/src/raytracer.h b/src/raytracer.h
index a48bdd2..40fccf2 100644
--- a/src/raytracer.h
+++ b/src/raytracer.h
@@ -5,12 +5,15 @@
 #include <numbers>
 
 using u32 = uint32_t;
+using u64 = uint64_t;
 
-constexpr double kInf = std::numeric_limits<double>::infinity();
-constexpr double kPi = std::numbers::pi_v<double>;
+using f64 = double;
+
+constexpr f64 kInf = std::numeric_limits<f64>::infinity();
+constexpr f64 kPi = std::numbers::pi_v<f64>;
 
 constexpr char newline = '\n';
 
-constexpr u32 FToU8(double x) { return static_cast<uint16_t>(255.999 * x); }
+constexpr u32 FToU8(f64 x) { return static_cast<uint16_t>(255.999 * x); }
 
-constexpr double deg2rad(double deg) { return deg * kPi / 180.0; }
+constexpr f64 deg2rad(f64 deg) { return deg * kPi / 180.0; }
diff --git a/src/renderer.h b/src/renderer.h
new file mode 100644
index 0000000..5e75940
--- /dev/null
+++ b/src/renderer.h
@@ -0,0 +1,79 @@
+#pragma once
+
+#include <iostream>
+
+#include "camera.h"
+#include "colour.h"
+#include "image.h"
+#include "interval.h"
+#include "rand.h"
+#include "ray.h"
+#include "raytracer.h"
+#include "renderobject.h"
+#include "vec3.h"
+
+class Renderer {
+   public:
+    constexpr explicit Renderer(Camera camera, u32 samples_per_pixel = 10)
+        : camera_{camera}, rand_{0}, samples_per_pixel_{samples_per_pixel} {}
+
+    constexpr Image Render(const RenderObject& world) {
+        Image img{camera_.image_width(), camera_.image_height()};
+
+        for (u32 j = 0; j < img.height(); j++) {
+            std::clog << "\rWriting line " << j << " of " << img.height() << std::flush;
+
+            for (u32 i = 0; i < img.width(); i++) {
+                Colour colour_sum{0.0, 0.0, 0.0};
+
+                for (u32 num_sample = 0; num_sample < samples_per_pixel_; num_sample++) {
+                    auto ray = SampleRay(i, j);
+
+                    colour_sum += Cast(ray, world);
+                }
+
+                img[i, j] = colour_sum / samples_per_pixel_;
+            }
+        }
+
+        return img;
+    }
+
+   private:
+    constexpr Ray SampleRay(u32 i, u32 j) {
+        auto pixel_centre = camera_.PixelToWorld(i, j);
+
+        pixel_centre += rand_.GenF64(-0.5, 0.5) * camera_.d_u_pixel();
+        pixel_centre += rand_.GenF64(-0.5, 0.5) * camera_.d_v_pixel();
+
+        auto ray_direction = pixel_centre - camera_.centre();
+
+        return Ray{camera_.centre(), ray_direction};
+    }
+
+    static constexpr Colour Cast(const Ray& ray, const RenderObject& world) {
+        auto hit_record = world.hit(ray, Interval::kPositive);
+
+        if (hit_record.has_value()) {
+            Vec3 n = hit_record->normal;
+
+            if (!hit_record->front_face) {
+                return Colour::kBlack;
+            }
+
+            return Colour{0.5 * (n + Vec3{1, 1, 1})};
+        }
+
+        auto unit_dir = ray.direction().normed();
+
+        f64 a = 0.5 * (unit_dir.y() + 1.0);
+
+        return (1.0 - a) * Colour{1.0, 1.0, 1.0} + a * Colour{0.5, 0.7, 1.0};
+    }
+
+    Camera camera_;
+
+    Random rand_;
+
+    u32 samples_per_pixel_;
+};
diff --git a/src/renderobject.h b/src/renderobject.h
index bbbec7b..70ab0c1 100644
--- a/src/renderobject.h
+++ b/src/renderobject.h
@@ -3,7 +3,6 @@
 #include <memory>
 #include <optional>
 
-#include "colour.h"
 #include "interval.h"
 #include "ray.h"
 #include "vec3.h"
@@ -11,7 +10,7 @@
 struct HitRecord {
     Point3 p;
     Vec3 normal;
-    double t = 0.0;
+    f64 t = 0.0;
     bool front_face = true;
 };
 
@@ -31,27 +30,3 @@ class RenderObject {
 };
 
 using SharedRenderObject = std::shared_ptr<RenderObject>;
-
-constexpr Colour Cast(const Ray& ray, const RenderObject& world) {
-    auto hit_record = world.hit(ray, Interval::kPositive);
-    // auto hit_record = world.hit(ray, Interval{0.505, kInf});
-
-    if (hit_record.has_value()) {
-        // assert(hit_record.front_face);
-
-        Vec3 n = hit_record->normal;
-
-        if (!hit_record->front_face) {
-            // return Colour{0.0, 0.0, 0.0};
-            return Colour::kBlack;
-        }
-
-        return Colour{0.5 * (n + Vec3{1, 1, 1})};
-    }
-
-    auto unit_dir = ray.direction().normed();
-
-    double a = 0.5 * (unit_dir.y() + 1.0);
-
-    return (1.0 - a) * Colour{1.0, 1.0, 1.0} + a * Colour{0.5, 0.7, 1.0};
-}
diff --git a/src/renderobjectlist.h b/src/renderobjectlist.h
index 8ba93c9..e716086 100644
--- a/src/renderobjectlist.h
+++ b/src/renderobjectlist.h
@@ -27,7 +27,7 @@ class RenderObjectList : public RenderObject {
     std::optional<HitRecord> hit(const Ray& ray, Interval ts) const override {
         std::optional<HitRecord> closest_hit_record = std::nullopt;
 
-        double closest_t = ts.max();
+        f64 closest_t = ts.max();
 
         for (const auto& obj : objs_) {
             Interval _ts{ts.min(), closest_t};
diff --git a/src/sphere.h b/src/sphere.h
index 34b2d81..852dd5f 100644
--- a/src/sphere.h
+++ b/src/sphere.h
@@ -6,29 +6,30 @@
 
 #include "interval.h"
 #include "ray.h"
+#include "raytracer.h"
 #include "renderobject.h"
 #include "vec3.h"
 
 class Sphere : public RenderObject {
    public:
     constexpr Sphere() = default;
-    constexpr Sphere(Point3 centre, double radius) : centre_{centre}, radius_{radius} {
+    constexpr Sphere(Point3 centre, f64 radius) : centre_{centre}, radius_{radius} {
         assert(radius >= 0);
     }
 
     constexpr Point3 centre() const { return centre_; }
-    constexpr double radius() const { return radius_; }
+    constexpr f64 radius() const { return radius_; }
 
     std::optional<HitRecord> hit(const Ray& ray, Interval ts) const override {
         HitRecord hit_record;
 
         Vec3 oc = ray.origin() - centre_;
 
-        double a = ray.direction().squared();
-        double b_half = dot(oc, ray.direction());
-        double c = oc.squared() - radius_ * radius_;
+        f64 a = ray.direction().squared();
+        f64 b_half = dot(oc, ray.direction());
+        f64 c = oc.squared() - radius_ * radius_;
 
-        auto discr = b_half * b_half - a * c;
+        f64 discr = b_half * b_half - a * c;
 
         if (discr < 0) {
             // miss
@@ -38,7 +39,7 @@ class Sphere : public RenderObject {
         // hit
 
         // smaller of the ts that hit the sphere
-        double t = (-b_half - std::sqrt(discr)) / a;
+        f64 t = (-b_half - std::sqrt(discr)) / a;
 
         if (t >= ts.max()) {
             // if the smaller t is already too large, we don't need to check the second one since it
@@ -77,5 +78,5 @@ class Sphere : public RenderObject {
 
    private:
     Point3 centre_{};
-    double radius_ = 0.0;
+    f64 radius_ = 0.0;
 };
diff --git a/src/vec3.h b/src/vec3.h
index f8dd25d..5d4794e 100644
--- a/src/vec3.h
+++ b/src/vec3.h
@@ -6,31 +6,33 @@
 #include <cstddef>
 #include <ostream>
 
+#include "raytracer.h"
+
 class Vec3 {
    public:
     static const Vec3 e_x;
     static const Vec3 e_y;
     static const Vec3 e_z;
 
-    constexpr Vec3(double x, double y, double z) : xyz_{x, y, z} {}
+    constexpr Vec3(f64 x, f64 y, f64 z) : xyz_{x, y, z} {}
     constexpr Vec3() : Vec3{0, 0, 0} {}
 
-    constexpr double& x() { return xyz_[0]; }
-    constexpr double& y() { return xyz_[1]; }
-    constexpr double& z() { return xyz_[2]; }
+    constexpr f64& x() { return xyz_[0]; }
+    constexpr f64& y() { return xyz_[1]; }
+    constexpr f64& z() { return xyz_[2]; }
 
-    constexpr double x() const { return xyz_[0]; }
-    constexpr double y() const { return xyz_[1]; }
-    constexpr double z() const { return xyz_[2]; }
+    constexpr f64 x() const { return xyz_[0]; }
+    constexpr f64 y() const { return xyz_[1]; }
+    constexpr f64 z() const { return xyz_[2]; }
 
     constexpr Vec3 operator-() const { return Vec3{-x(), -y(), -z()}; }
 
-    constexpr double& operator[](std::size_t i) {
+    constexpr f64& operator[](std::size_t i) {
         assert(i <= 3);
         return xyz_[i];
     }
 
-    constexpr double operator[](std::size_t i) const {
+    constexpr f64 operator[](std::size_t i) const {
         assert(i <= 3);
         return xyz_[i];
     }
@@ -43,7 +45,7 @@ class Vec3 {
         return *this;
     }
 
-    constexpr Vec3& operator*=(double t) {
+    constexpr Vec3& operator*=(f64 t) {
         x() *= t;
         y() *= t;
         z() *= t;
@@ -51,15 +53,15 @@ class Vec3 {
         return *this;
     }
 
-    constexpr Vec3& operator/=(double t) {
+    constexpr Vec3& operator/=(f64 t) {
         *this *= 1 / t;
 
         return *this;
     }
 
-    constexpr double squared() const { return x() * x() + y() * y() + z() * z(); }
+    constexpr f64 squared() const { return x() * x() + y() * y() + z() * z(); }
 
-    constexpr double norm() const { return std::sqrt(squared()); }
+    constexpr f64 norm() const { return std::sqrt(squared()); }
 
     constexpr Vec3 normed() const {
         auto r = *this;
@@ -68,7 +70,7 @@ class Vec3 {
     }
 
    private:
-    std::array<double, 3> xyz_;
+    std::array<f64, 3> xyz_;
 };
 
 constexpr Vec3 Vec3::e_x{1.0, 0.0, 0.0};
@@ -93,15 +95,15 @@ constexpr Vec3 operator*(const Vec3& u, const Vec3& v) {
     return {u.x() * v.x(), u.y() * v.y(), u.z() * v.z()};
 }
 
-constexpr Vec3 operator*(double t, const Vec3& v) {
+constexpr Vec3 operator*(f64 t, const Vec3& v) {
     Vec3 out = v;
     out *= t;
     return out;
 }
 
-constexpr Vec3 operator/(const Vec3& v, double t) { return (1 / t) * v; }
+constexpr Vec3 operator/(const Vec3& v, f64 t) { return (1 / t) * v; }
 
-constexpr double dot(const Vec3& u, const Vec3& v) {
+constexpr f64 dot(const Vec3& u, const Vec3& v) {
     Vec3 tmp = u * v;
     return tmp.x() + tmp.y() + tmp.z();
 }