finished 6.7

src/camera.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include "ray.h"
+#include "raytracer.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;
+
+        Vec3 u_viewport = viewport_width * Vec3::e_x;
+        Vec3 v_viewport = -viewport_height * Vec3::e_y;
+
+        d_u_pixel_ = u_viewport / image_width;
+        d_v_pixel_ = v_viewport / image_height;
+
+        // upper left of viewport: move from camera centre `focal_length` in z direction, then half
+        // of the viewport length in x and y direction respectively
+        auto viewport_upper_left =
+            centre_ - focal_length * Vec3::e_z - u_viewport / 2 - v_viewport / 2;
+
+        pixel_00_ = viewport_upper_left + 0.5 * d_u_pixel_ + 0.5 * d_v_pixel_;
+    }
+
+    constexpr Vec3 centre() const { return centre_; }
+
+    constexpr Vec3 Image2World(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
+    Vec3 pixel_00_;
+
+    // Vec3 pointing from pixel to right/lower neighbour resp.
+    Vec3 d_u_pixel_;
+    Vec3 d_v_pixel_;
+};

src/colour.h

@@ -3,9 +3,13 @@
 #include <cassert>
 #include <iomanip>
 #include <ios>
+#include <iostream>
 #include <ostream>
+#include <sstream>
+#include <string>
 
-#include "util.h"
+#include "raytracer.h"
+#include "vec3.h"
 
 class Colour {
    public:
@@ -19,6 +23,8 @@ class Colour {
         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_; }
@@ -27,6 +33,18 @@ class Colour {
     constexpr double g() const { return g_; }
     constexpr double b() const { return b_; }
 
+    std::string to_string() const {
+        std::stringstream ss;
+
+        ss << '#';
+
+        ss << std::hex << std::setfill('0') << std::setw(2) << FToU8(r());
+        ss << std::hex << std::setfill('0') << std::setw(2) << FToU8(g());
+        ss << std::hex << std::setfill('0') << std::setw(2) << FToU8(b());
+
+        return ss.str();
+    }
+
    private:
     double r_;
     double g_;
@@ -35,20 +53,14 @@ class Colour {
 
 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*(double t, Colour col) { return {t * col.r(), t * col.g(), t * col.b()}; }
 
 constexpr Colour operator+(Colour c1, Colour c2) {
     return {c1.r() + c2.r(), c1.g() + c2.g(), c1.b() + c2.b()};
 }
 
-inline std::ostream& operator<<(std::ostream& out, Colour colour) {
-    out << '#';
+inline std::ostream& operator<<(std::ostream& os, Colour colour) {
+    os << FToU8(colour.r()) << ' ' << FToU8(colour.g()) << ' ' << FToU8(colour.b());
 
-    out << std::hex << std::setfill('0') << std::setw(2) << FToU8(colour.r());
-    out << std::hex << std::setfill('0') << std::setw(2) << FToU8(colour.g());
-    out << std::hex << std::setfill('0') << std::setw(2) << FToU8(colour.b());
-
-    return out;
+    return os;
 }

src/image.h

@@ -2,26 +2,25 @@
 
 #include <cassert>
 #include <cstddef>
-#include <cstdint>
 #include <iostream>
 #include <memory>
 #include <ostream>
 
 #include "colour.h"
-#include "util.h"
+#include "raytracer.h"
 
 class Image {
    public:
-    constexpr Image(uint32_t width, uint32_t height)
+    constexpr Image(u32 width, u32 height)
         // NOLINTNEXTLINE(modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
         : buf_(std::make_unique_for_overwrite<Colour[]>(static_cast<std::size_t>(width) * height)),
           width_{width},
           height_{height} {}
 
-    constexpr uint32_t width() const { return width_; }
-    constexpr uint32_t height() const { return height_; }
+    constexpr u32 width() const { return width_; }
+    constexpr u32 height() const { return height_; }
 
-    Colour& operator[](uint32_t x, uint32_t y) {
+    Colour& operator[](u32 x, u32 y) {
         assert(x < width_);
         assert(y < height_);
 
@@ -30,7 +29,7 @@ class Image {
         return buf_[y * width_ + x];
     }
 
-    Colour operator[](uint32_t x, uint32_t y) const {
+    Colour operator[](u32 x, u32 y) const {
         assert(x < width_);
         assert(y < height_);
 
@@ -43,24 +42,26 @@ class Image {
     // NOLINTNEXTLINE(modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
     std::unique_ptr<Colour[]> buf_;
 
-    uint32_t width_;
-    uint32_t height_;
+    u32 width_;
+    u32 height_;
 };
 
 constexpr std::ostream& operator<<(std::ostream& os, const Image& img) {
-    os << "P3\n" << img.width() << ' ' << img.height() << "\n255\n";
+    os << "P3" << newline;
+    os << img.width() << ' ' << img.height() << newline;
+    os << "255" << newline;
 
-    for (uint32_t j = 0; j < img.height(); j++) {
+    for (u32 j = 0; j < img.height(); j++) {
         std::clog << "\rWriting line " << j << " of " << img.height() << std::flush;
 
-        for (uint32_t i = 0; i < img.width(); i++) {
+        for (u32 i = 0; i < img.width(); i++) {
             const Colour col = img[i, j];
 
-            os << FToU8(col.r()) << ' ' << FToU8(col.g()) << ' ' << FToU8(col.b()) << '\n';
+            os << col << newline;
         }
     }
 
-    std::clog << "\rDone                                                " << std::endl;
+    std::clog << "\rDone                                                " << newline;
 
     return os;
 }

src/main.cc

@@ -1,26 +1,30 @@
-#include <cstdint>
 #include <iostream>
+#include <memory>
 
+#include "camera.h"
 #include "colour.h"
 #include "image.h"
 #include "ray.h"
+#include "raytracer.h"
+#include "renderobject.h"
+#include "renderobjectlist.h"
+#include "sphere.h"
 #include "vec3.h"
 
-bool IntersectsSphere(const Ray& r, const Point3& centre, double radius) {
-    Vec3 oc = r.origin() - centre;
+Colour RayColour(const Ray& ray, const RenderObject& world) {
+    auto hit_record = world.hit(ray, 0.0, kInf);
 
-    double a = r.direction().squared();
-    double b = 2.0 * dot(oc, r.direction());
-    double c = oc.squared() - radius * radius;
+    if (hit_record.has_value()) {
+        // assert(hit_record.front_face);
 
-    auto discr = b * b - 4 * a * c;
+        Vec3 n = hit_record->normal;
 
-    return discr >= 0;
-}
+        if (!hit_record->front_face) {
+            // return Colour{0.0, 0.0, 0.0};
+            return Colour{0.5 * (n + Vec3{1, 1, 1})};
+        }
 
-Colour RayColour(const Ray& ray) {
-    if (IntersectsSphere(ray, -Vec3::e_z, 0.5)) {
-        return {1.0, 0.0, 0.0};
+        return Colour{0.5 * (n + Vec3{1, 1, 1})};
     }
 
     auto unit_dir = ray.direction().normed();
@@ -31,54 +35,42 @@ Colour RayColour(const Ray& ray) {
 }
 
 int main(int /* argc */, char* /* argv */[]) {
-    // image properties
+    // image
 
     constexpr double aspect_ratio = 16.0 / 9.0;
 
-    constexpr uint32_t image_width = 800;
+    constexpr u32 image_width = 800;
 
-    constexpr auto image_height = static_cast<uint32_t>(image_width / aspect_ratio);
+    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::e_z, 0.5));
+
     // camera
 
     constexpr double focal_length = 1.0;
 
-    constexpr double viewport_height = 2.0;
-    constexpr double viewport_width =
-        viewport_height * static_cast<double>(image_width) / image_height;
+    constexpr Point3 camera_centre{0.0, 0.0, 0.0};
 
-    Point3 camera_centre{0.0, 0.0, 0.0};
-
-    // viewport
-
-    constexpr Vec3 u_viewport = viewport_width * Vec3::e_x;
-    constexpr Vec3 v_viewport = -viewport_height * Vec3::e_y;
-
-    constexpr Vec3 d_u_pixel = u_viewport / image_width;
-    constexpr Vec3 d_v_pixel = v_viewport / image_height;
-
-    auto viewport_upper_left =
-        camera_centre - focal_length * Vec3::e_z - u_viewport / 2 - v_viewport / 2;
-
-    auto pixel_00 = viewport_upper_left + 0.5 * d_u_pixel + 0.5 * d_v_pixel;
+    Camera camera{camera_centre, img.width(), img.height(), focal_length};
 
     // render
 
-    Image img{image_width, image_height};
-
-    for (uint32_t j = 0; j < img.height(); j++) {
+    for (u32 j = 0; j < img.height(); j++) {
         std::clog << "\rWriting line " << j << " of " << img.height() << std::flush;
 
-        for (uint32_t i = 0; i < img.width(); i++) {
-            auto pixel_centre = pixel_00 + i * d_u_pixel + j * d_v_pixel;
+        for (u32 i = 0; i < img.width(); i++) {
+            auto ray = camera.CastRay(i, j);
 
-            auto ray_direction = pixel_centre - camera_centre;
-
-            Ray r{camera_centre, ray_direction};
-
-            img[i, j] = RayColour(r);
+            img[i, j] = RayColour(ray, world);
         }
     }
 

src/ray.h

@@ -4,14 +4,14 @@
 
 class Ray {
    public:
-    Ray() = default;
+    constexpr Ray() = default;
 
-    Ray(const Point3& origin, const Vec3& direction) : orig_{origin}, dir_{direction} {}
+    constexpr Ray(const Point3& origin, const Vec3& direction) : orig_{origin}, dir_{direction} {}
 
     Point3 origin() const { return orig_; }
     Vec3 direction() const { return dir_; }
 
-    Point3 At(double t) { return orig_ + t * dir_; }
+    constexpr Point3 At(double t) const { return orig_ + t * dir_; }
 
    private:
     Point3 orig_;

src/raytracer.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <cstdint>
+#include <limits>
+#include <numbers>
+
+using u32 = uint32_t;
+
+constexpr double kInf = std::numeric_limits<double>::infinity();
+constexpr double kPi = std::numbers::pi_v<double>;
+
+constexpr char newline = '\n';
+
+constexpr u32 FToU8(double x) { return static_cast<uint16_t>(255.999 * x); }
+
+constexpr double deg2rad(double deg) { return deg * kPi / 180.0; }

src/renderobject.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <memory>
+#include <optional>
+
+#include "ray.h"
+#include "vec3.h"
+
+struct HitRecord {
+    Point3 p;
+    Vec3 normal;
+    double t = 0.0;
+    bool front_face = true;
+};
+
+class RenderObject {
+   public:
+    RenderObject() = default;
+
+    RenderObject(const RenderObject& other) = default;
+    RenderObject& operator=(const RenderObject&) = default;
+
+    RenderObject(RenderObject&& other) = default;
+    RenderObject& operator=(RenderObject&&) = default;
+
+    virtual ~RenderObject() = default;
+
+    virtual std::optional<HitRecord> hit(const Ray& ray, double t_min, double t_max) const = 0;
+};
+
+using SharedRenderObject = std::shared_ptr<RenderObject>;

src/renderobjectlist.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <initializer_list>
+#include <optional>
+#include <vector>
+
+#include "ray.h"
+#include "raytracer.h"
+#include "renderobject.h"
+
+class RenderObjectList : public RenderObject {
+   public:
+    constexpr RenderObjectList() = default;
+    // explicit RenderObjectList(const SharedRenderObject& obj) { Append(obj); }
+    RenderObjectList(std::initializer_list<SharedRenderObject> objs) : objs_{objs} {}
+
+    constexpr auto begin() { return objs_.begin(); }
+    constexpr auto end() { return objs_.end(); }
+
+    constexpr auto begin() const { return objs_.begin(); }
+    constexpr auto end() const { return objs_.end(); }
+
+    void Add(const SharedRenderObject& obj) { objs_.push_back(obj); }
+
+    void Clear() { objs_.clear(); }
+
+    std::optional<HitRecord> hit(const Ray& ray, double t_min, double t_max) const override {
+        std::optional<HitRecord> closest_hit_record = std::nullopt;
+
+        double closest_t = kInf;
+
+        for (const auto& obj : objs_) {
+            auto hit_record = obj->hit(ray, t_min, t_max);
+
+            if (hit_record.has_value() && hit_record->t < closest_t) {
+                closest_hit_record = hit_record;
+                closest_t = hit_record->t;
+            }
+        }
+
+        return closest_hit_record;
+    }
+
+   private:
+    std::vector<SharedRenderObject> objs_;
+};

src/sphere.h

@@ -0,0 +1,79 @@
+#pragma once
+
+#include <cassert>
+#include <cmath>
+#include <optional>
+
+#include "ray.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} {
+        assert(radius >= 0);
+    }
+
+    constexpr Point3 centre() const { return centre_; }
+    constexpr double radius() const { return radius_; }
+
+    std::optional<HitRecord> hit(const Ray& ray, double t_min, double t_max) 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_;
+
+        auto discr = b_half * b_half - a * c;
+
+        if (discr < 0) {
+            // miss
+            return std::nullopt;
+        }
+
+        // hit
+
+        // smaller of the ts that hit the sphere
+        double t = (-b_half - std::sqrt(discr)) / a;
+
+        if (t > t_max) {
+            // if the smaller t is already too large, we don't need to check the second one since it
+            // will be even larger
+
+            return std::nullopt;
+        }
+
+        if (t < t_min) {
+            // if the smaller t is too small, check the larger one
+
+            t = (-b_half + std::sqrt(discr)) / a;
+
+            if (t < t_min || t > t_max) {
+                // larger t also out of range: return false
+
+                return std::nullopt;
+            }
+
+            // smaller t hits front side, smaller t hits back side
+            // TODO: what if our hit t is less than 0? is that case even relevant?
+            hit_record.front_face = false;
+        }
+
+        hit_record.t = t;
+        hit_record.p = ray.At(t);
+        hit_record.normal = (hit_record.p - centre_) / radius_;
+
+        if (!hit_record.front_face) {
+            hit_record.normal = -hit_record.normal;
+        }
+
+        return hit_record;
+    }
+
+   private:
+    Point3 centre_{};
+    double radius_ = 0.0;
+};

src/util.h

@@ -1,6 +0,0 @@
-#pragma once
-
-#include <cstdint>
-constexpr uint32_t FToU8(double x) {
-    return static_cast<uint16_t>(255.999 * x);
-}

src/vec3.h

@@ -3,6 +3,7 @@
 #include <array>
 #include <cassert>
 #include <cmath>
+#include <cstddef>
 #include <ostream>
 
 class Vec3 {
@@ -86,9 +87,7 @@ constexpr Vec3 operator+(const Vec3& u, const Vec3& v) {
     return out;
 }
 
-constexpr Vec3 operator-(const Vec3& u, const Vec3& v) {
-    return u + (-v);
-}
+constexpr Vec3 operator-(const Vec3& u, const Vec3& v) { return u + (-v); }
 
 constexpr Vec3 operator*(const Vec3& u, const Vec3& v) {
     return {u.x() * v.x(), u.y() * v.y(), u.z() * v.z()};
@@ -100,9 +99,7 @@ constexpr Vec3 operator*(double t, const Vec3& v) {
     return out;
 }
 
-constexpr Vec3 operator/(const Vec3& v, double t) {
-    return (1 / t) * v;
-}
+constexpr Vec3 operator/(const Vec3& v, double t) { return (1 / t) * v; }
 
 constexpr double dot(const Vec3& u, const Vec3& v) {
     Vec3 tmp = u * v;
@@ -114,6 +111,4 @@ constexpr Vec3 cross(const Vec3& u, const Vec3& v) {
             u.x() * v.y() - u.y() - v.x()};
 }
 
-constexpr Vec3 normed(const Vec3& v) {
-    return v.normed();
-}
+constexpr Vec3 normed(const Vec3& v) { return v.normed(); }