First commit of code for Ray Tracing in One Weekend

camera.h

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+#ifndef CAMERAH
+#define CAMERAH
+#include "ray.h"
+
+vec3 random_in_unit_disk() {
+    vec3 p;
+    do {
+        p = 2.0*vec3(drand48(),drand48(),0) - vec3(1,1,0);
+    } while (dot(p,p) >= 1.0);
+    return p;
+}
+
+class camera {
+    public:
+        camera(vec3 lookfrom, vec3 lookat, vec3 vup, float vfov, float aspect, float aperture, float focus_dist) { // vfov is top to bottom in degrees
+            lens_radius = aperture / 2;
+            float theta = vfov*M_PI/180;
+            float half_height = tan(theta/2);
+            float half_width = aspect * half_height;
+            origin = lookfrom;
+            w = unit_vector(lookfrom - lookat);
+            u = unit_vector(cross(vup, w));
+            v = cross(w, u);
+            lower_left_corner = origin  - half_width*focus_dist*u -half_height*focus_dist*v - focus_dist*w;
+            horizontal = 2*half_width*focus_dist*u;
+            vertical = 2*half_height*focus_dist*v;
+        }
+        ray get_ray(float s, float t) {
+            vec3 rd = lens_radius*random_in_unit_disk();
+            vec3 offset = u * rd.x() + v * rd.y();
+            return ray(origin + offset, lower_left_corner + s*horizontal + t*vertical - origin - offset); 
+        }
+
+        vec3 origin;
+        vec3 lower_left_corner;
+        vec3 horizontal;
+        vec3 vertical;
+        vec3 u, v, w;
+        float lens_radius;
+};
+#endif
+
+
+
+

hitable.h

@@ -0,0 +1,27 @@
+#ifndef HITABLEH
+#define HITABLEH 
+
+#include "ray.h"
+
+class material;
+
+
+
+struct hit_record
+{
+    float t;  
+    vec3 p;
+    vec3 normal; 
+    material *mat_ptr;
+};
+
+class hitable  {
+    public:
+        virtual bool hit(const ray& r, float t_min, float t_max, hit_record& rec) const = 0;
+};
+
+#endif
+
+
+
+

hitable_list.h

@@ -0,0 +1,30 @@
+#ifndef HITABLELISTH
+#define HITABLELISTH
+
+#include "hitable.h"
+
+class hitable_list: public hitable  {
+    public:
+        hitable_list() {}
+        hitable_list(hitable **l, int n) {list = l; list_size = n; }
+        virtual bool hit(const ray& r, float tmin, float tmax, hit_record& rec) const;
+        hitable **list;
+        int list_size;
+};
+
+bool hitable_list::hit(const ray& r, float t_min, float t_max, hit_record& rec) const {
+        hit_record temp_rec;
+        bool hit_anything = false;
+        double closest_so_far = t_max;
+        for (int i = 0; i < list_size; i++) {
+            if (list[i]->hit(r, t_min, closest_so_far, temp_rec)) {
+                hit_anything = true;
+                closest_so_far = temp_rec.t;
+                rec = temp_rec;
+            }
+        }
+        return hit_anything;
+}
+
+#endif
+

main.cc

@@ -0,0 +1,103 @@
+#include <iostream>
+#include "sphere.h"
+#include "hitable_list.h"
+#include "float.h"
+#include "camera.h"
+#include "material.h"
+
+
+vec3 color(const ray& r, hitable *world, int depth) {
+    hit_record rec;
+    if (world->hit(r, 0.001, MAXFLOAT, rec)) { 
+        ray scattered;
+        vec3 attenuation;
+        if (depth < 50 && rec.mat_ptr->scatter(r, rec, attenuation, scattered)) {
+             return attenuation*color(scattered, world, depth+1);
+        }
+        else {
+            return vec3(0,0,0);
+        }
+    }
+    else {
+        vec3 unit_direction = unit_vector(r.direction());
+        float t = 0.5*(unit_direction.y() + 1.0);
+        return (1.0-t)*vec3(1.0, 1.0, 1.0) + t*vec3(0.5, 0.7, 1.0);
+    }
+}
+
+
+hitable *random_scene() {
+    int n = 500;
+    hitable **list = new hitable*[n+1];
+    list[0] =  new sphere(vec3(0,-1000,0), 1000, new lambertian(vec3(0.5, 0.5, 0.5)));
+    int i = 1;
+    for (int a = -11; a < 11; a++) {
+        for (int b = -11; b < 11; b++) {
+            float choose_mat = drand48();
+            vec3 center(a+0.9*drand48(),0.2,b+0.9*drand48()); 
+            if ((center-vec3(4,0.2,0)).length() > 0.9) { 
+                if (choose_mat < 0.8) {  // diffuse
+                    list[i++] = new sphere(center, 0.2, new lambertian(vec3(drand48()*drand48(), drand48()*drand48(), drand48()*drand48())));
+                }
+                else if (choose_mat < 0.95) { // metal
+                    list[i++] = new sphere(center, 0.2,
+                            new metal(vec3(0.5*(1 + drand48()), 0.5*(1 + drand48()), 0.5*(1 + drand48())),  0.5*drand48()));
+                }
+                else {  // glass
+                    list[i++] = new sphere(center, 0.2, new dielectric(1.5));
+                }
+            }
+        }
+    }
+
+    list[i++] = new sphere(vec3(0, 1, 0), 1.0, new dielectric(1.5));
+    list[i++] = new sphere(vec3(-4, 1, 0), 1.0, new lambertian(vec3(0.4, 0.2, 0.1)));
+    list[i++] = new sphere(vec3(4, 1, 0), 1.0, new metal(vec3(0.7, 0.6, 0.5), 0.0));
+
+    return new hitable_list(list,i);
+}
+
+int main() {
+    int nx = 1200;
+    int ny = 800;
+    int ns = 10;
+    std::cout << "P3\n" << nx << " " << ny << "\n255\n";
+    hitable *list[5];
+    float R = cos(M_PI/4);
+    list[0] = new sphere(vec3(0,0,-1), 0.5, new lambertian(vec3(0.1, 0.2, 0.5)));
+    list[1] = new sphere(vec3(0,-100.5,-1), 100, new lambertian(vec3(0.8, 0.8, 0.0)));
+    list[2] = new sphere(vec3(1,0,-1), 0.5, new metal(vec3(0.8, 0.6, 0.2), 0.0));
+    list[3] = new sphere(vec3(-1,0,-1), 0.5, new dielectric(1.5));
+    list[4] = new sphere(vec3(-1,0,-1), -0.45, new dielectric(1.5));
+    hitable *world = new hitable_list(list,5);
+    world = random_scene();
+
+    vec3 lookfrom(13,2,3);
+    vec3 lookat(0,0,0);
+    float dist_to_focus = 10.0;
+    float aperture = 0.1;
+
+    camera cam(lookfrom, lookat, vec3(0,1,0), 20, float(nx)/float(ny), aperture, dist_to_focus);
+
+    for (int j = ny-1; j >= 0; j--) {
+        for (int i = 0; i < nx; i++) {
+            vec3 col(0, 0, 0);
+            for (int s=0; s < ns; s++) {
+                float u = float(i + drand48()) / float(nx);
+                float v = float(j + drand48()) / float(ny);
+                ray r = cam.get_ray(u, v);
+                vec3 p = r.point_at_parameter(2.0);
+                col += color(r, world,0);
+            }
+            col /= float(ns);
+            col = vec3( sqrt(col[0]), sqrt(col[1]), sqrt(col[2]) );
+            int ir = int(255.99*col[0]); 
+            int ig = int(255.99*col[1]); 
+            int ib = int(255.99*col[2]); 
+            std::cout << ir << " " << ig << " " << ib << "\n";
+        }
+    }
+}
+
+
+

material.h

@@ -0,0 +1,115 @@
+#ifndef MATERIALH
+#define MATERIALH 
+
+struct hit_record;
+
+#include "ray.h"
+#include "hitable.h"
+
+
+float schlick(float cosine, float ref_idx) {
+    float r0 = (1-ref_idx) / (1+ref_idx);
+    r0 = r0*r0;
+    return r0 + (1-r0)*pow((1 - cosine),5);
+}
+
+bool refract(const vec3& v, const vec3& n, float ni_over_nt, vec3& refracted) {
+    vec3 uv = unit_vector(v);
+    float dt = dot(uv, n);
+    float discriminant = 1.0 - ni_over_nt*ni_over_nt*(1-dt*dt);
+    if (discriminant > 0) {
+        refracted = ni_over_nt*(uv - n*dt) - n*sqrt(discriminant);
+        return true;
+    }
+    else 
+        return false;
+}
+
+
+vec3 reflect(const vec3& v, const vec3& n) {
+     return v - 2*dot(v,n)*n;
+}
+
+
+vec3 random_in_unit_sphere() {
+    vec3 p;
+    do {
+        p = 2.0*vec3(drand48(),drand48(),drand48()) - vec3(1,1,1);
+    } while (p.squared_length() >= 1.0);
+    return p;
+}
+
+
+class material  {
+    public:
+        virtual bool scatter(const ray& r_in, const hit_record& rec, vec3& attenuation, ray& scattered) const = 0;
+};
+
+class lambertian : public material {
+    public:
+        lambertian(const vec3& a) : albedo(a) {}
+        virtual bool scatter(const ray& r_in, const hit_record& rec, vec3& attenuation, ray& scattered) const  {
+             vec3 target = rec.p + rec.normal + random_in_unit_sphere();
+             scattered = ray(rec.p, target-rec.p);
+             attenuation = albedo;
+             return true;
+        }
+
+        vec3 albedo;
+};
+
+class metal : public material {
+    public:
+        metal(const vec3& a, float f) : albedo(a) { if (f < 1) fuzz = f; else fuzz = 1; }
+        virtual bool scatter(const ray& r_in, const hit_record& rec, vec3& attenuation, ray& scattered) const  {
+            vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
+            scattered = ray(rec.p, reflected + fuzz*random_in_unit_sphere());
+            attenuation = albedo;
+            return (dot(scattered.direction(), rec.normal) > 0);
+        }
+        vec3 albedo;
+        float fuzz;
+};
+
+class dielectric : public material { 
+    public:
+        dielectric(float ri) : ref_idx(ri) {}
+        virtual bool scatter(const ray& r_in, const hit_record& rec, vec3& attenuation, ray& scattered) const  {
+             vec3 outward_normal;
+             vec3 reflected = reflect(r_in.direction(), rec.normal);
+             float ni_over_nt;
+             attenuation = vec3(1.0, 1.0, 1.0); 
+             vec3 refracted;
+             float reflect_prob;
+             float cosine;
+             if (dot(r_in.direction(), rec.normal) > 0) {
+                  outward_normal = -rec.normal;
+                  ni_over_nt = ref_idx;
+         //         cosine = ref_idx * dot(r_in.direction(), rec.normal) / r_in.direction().length();
+                  cosine = dot(r_in.direction(), rec.normal) / r_in.direction().length();
+                  cosine = sqrt(1 - ref_idx*ref_idx*(1-cosine*cosine));
+             }
+             else {
+                  outward_normal = rec.normal;
+                  ni_over_nt = 1.0 / ref_idx;
+                  cosine = -dot(r_in.direction(), rec.normal) / r_in.direction().length();
+             }
+             if (refract(r_in.direction(), outward_normal, ni_over_nt, refracted)) 
+                reflect_prob = schlick(cosine, ref_idx);
+             else 
+                reflect_prob = 1.0;
+             if (drand48() < reflect_prob) 
+                scattered = ray(rec.p, reflected);
+             else 
+                scattered = ray(rec.p, refracted);
+             return true;
+        }
+
+        float ref_idx;
+};
+
+#endif
+
+
+
+

ray.h

@@ -0,0 +1,20 @@
+#ifndef RAYH
+#define RAYH
+#include "vec3.h"
+
+class ray
+{
+    public:
+        ray() {}
+        ray(const vec3& a, const vec3& b) { A = a; B = b; }  
+        vec3 origin() const       { return A; }
+        vec3 direction() const    { return B; }
+        vec3 point_at_parameter(float t) const { return A + t*B; }
+
+        vec3 A;
+        vec3 B;
+};
+
+#endif 
+
+

sphere.h

@@ -0,0 +1,47 @@
+#ifndef SPHEREH
+#define SPHEREH
+
+#include "hitable.h"
+
+class sphere: public hitable  {
+    public:
+        sphere() {}
+        sphere(vec3 cen, float r, material *m) : center(cen), radius(r), mat_ptr(m)  {};
+        virtual bool hit(const ray& r, float tmin, float tmax, hit_record& rec) const;
+        vec3 center;
+        float radius;
+        material *mat_ptr;
+};
+
+bool sphere::hit(const ray& r, float t_min, float t_max, hit_record& rec) const {
+    vec3 oc = r.origin() - center;
+    float a = dot(r.direction(), r.direction());
+    float b = dot(oc, r.direction());
+    float c = dot(oc, oc) - radius*radius;
+    float discriminant = b*b - a*c;
+    if (discriminant > 0) {
+        float temp = (-b - sqrt(discriminant))/a;
+        if (temp < t_max && temp > t_min) {
+            rec.t = temp;
+            rec.p = r.point_at_parameter(rec.t);
+            rec.normal = (rec.p - center) / radius;
+            rec.mat_ptr = mat_ptr;
+            return true;
+        }
+        temp = (-b + sqrt(discriminant)) / a;
+        if (temp < t_max && temp > t_min) {
+            rec.t = temp;
+            rec.p = r.point_at_parameter(rec.t);
+            rec.normal = (rec.p - center) / radius;
+            rec.mat_ptr = mat_ptr;
+            return true;
+        }
+    }
+    return false;
+}
+
+
+#endif
+
+
+