Book 1 render updates: code changes

- Add more double-line spacers
- Organize main() chunks: image params, then world definitions, then
  camera defs, then render
- Change class order in material.h to match book definition order
- Eliminate duplicated code in dielectric::scatter()
- Delete vestigal vec3::write_color() method (now in color.h)

Author: hollasch

src/InOneWeekend/hittable.h

@@ -16,6 +16,7 @@
 
 class material;
 
+
 struct hit_record {
     point3 p;
     vec3 normal;
@@ -35,4 +36,5 @@ class hittable {
         virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const = 0;
 };
 
+
 #endif

src/InOneWeekend/main.cc

@@ -89,16 +89,21 @@ hittable_list random_scene() {
 
 
 int main() {
+
+    // Image
+
     const auto aspect_ratio = 16.0 / 9.0;
     const int image_width = 1200;
     const int image_height = static_cast<int>(image_width / aspect_ratio);
     const int samples_per_pixel = 10;
     const int max_depth = 50;
 
-    std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
+    // World
 
     auto world = random_scene();
 
+    // Camera
+
     point3 lookfrom(13,2,3);
     point3 lookat(0,0,0);
     vec3 vup(0,1,0);
@@ -107,10 +112,14 @@ int main() {
 
     camera cam(lookfrom, lookat, vup, 20, aspect_ratio, aperture, dist_to_focus);
 
+    // Render
+
+    std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
+
     for (int j = image_height-1; j >= 0; --j) {
         std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
         for (int i = 0; i < image_width; ++i) {
-            color pixel_color;
+            color pixel_color(0,0,0);
             for (int s = 0; s < samples_per_pixel; ++s) {
                 auto u = (i + random_double()) / (image_width-1);
                 auto v = (j + random_double()) / (image_height-1);

src/InOneWeekend/material.h

@@ -24,58 +24,21 @@ double schlick(double cosine, double ref_idx) {
 }
 
 
-class material  {
+class material {
     public:
         virtual bool scatter(
             const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
         ) const = 0;
 };
 
 
-class dielectric : public material {
-    public:
-        dielectric(double ri) : ref_idx(ri) {}
-
-        virtual bool scatter(
-            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
-        ) const {
-            attenuation = color(1.0, 1.0, 1.0);
-            double etai_over_etat = (rec.front_face) ? (1.0 / ref_idx) : (ref_idx);
-
-            vec3 unit_direction = unit_vector(r_in.direction());
-            double cos_theta = fmin(dot(-unit_direction, rec.normal), 1.0);
-            double sin_theta = sqrt(1.0 - cos_theta*cos_theta);
-            if (etai_over_etat * sin_theta > 1.0 ) {
-                vec3 reflected = reflect(unit_direction, rec.normal);
-                scattered = ray(rec.p, reflected);
-                return true;
-            }
-
-            double reflect_prob = schlick(cos_theta, etai_over_etat);
-            if (random_double() < reflect_prob)
-            {
-                vec3 reflected = reflect(unit_direction, rec.normal);
-                scattered = ray(rec.p, reflected);
-                return true;
-            }
-
-            vec3 refracted = refract(unit_direction, rec.normal, etai_over_etat);
-            scattered = ray(rec.p, refracted);
-            return true;
-        }
-
-    public:
-        double ref_idx;
-};
-
-
 class lambertian : public material {
     public:
         lambertian(const color& a) : albedo(a) {}
 
         virtual bool scatter(
             const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
-        ) const  {
+        ) const {
             vec3 scatter_direction = rec.normal + random_unit_vector();
             scattered = ray(rec.p, scatter_direction);
             attenuation = albedo;
@@ -93,7 +56,7 @@ class metal : public material {
 
         virtual bool scatter(
             const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
-        ) const  {
+        ) const {
             vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
             scattered = ray(rec.p, reflected + fuzz*random_in_unit_sphere());
             attenuation = albedo;
@@ -106,4 +69,36 @@ class metal : public material {
 };
 
 
+class dielectric : public material {
+    public:
+        dielectric(double ri) : ref_idx(ri) {}
+
+        virtual bool scatter(
+            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
+        ) const {
+            attenuation = color(1.0, 1.0, 1.0);
+            double etai_over_etat = rec.front_face ? (1.0 / ref_idx) : ref_idx;
+
+            vec3 unit_direction = unit_vector(r_in.direction());
+            double cos_theta = fmin(dot(-unit_direction, rec.normal), 1.0);
+            double sin_theta = sqrt(1.0 - cos_theta*cos_theta);
+
+            if (  (etai_over_etat * sin_theta > 1.0)
+               || (random_double() < schlick(cos_theta, etai_over_etat))
+               ) {
+                vec3 reflected = reflect(unit_direction, rec.normal);
+                scattered = ray(rec.p, reflected);
+                return true;
+            }
+
+            vec3 refracted = refract(unit_direction, rec.normal, etai_over_etat);
+            scattered = ray(rec.p, refracted);
+            return true;
+        }
+
+    public:
+        double ref_idx;
+};
+
+
 #endif

src/InOneWeekend/sphere.h

@@ -16,7 +16,7 @@
 #include "hittable.h"
 
 
-class sphere: public hittable  {
+class sphere : public hittable {
     public:
         sphere() {}
 
@@ -42,7 +42,7 @@ bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) cons
     if (discriminant > 0) {
         auto root = sqrt(discriminant);
 
-        auto temp = (-half_b - root)/a;
+        auto temp = (-half_b - root) / a;
         if (temp < t_max && temp > t_min) {
             rec.t = temp;
             rec.p = r.at(rec.t);
@@ -62,7 +62,9 @@ bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) cons
             return true;
         }
     }
+
     return false;
 }
 
+
 #endif

src/TheNextWeek/main.cc

@@ -328,21 +328,22 @@ hittable_list final_scene() {
 
 
 int main() {
+
+    // Image
+
     const auto aspect_ratio = 1.0 / 1.0;
     const int image_width = 600;
     const int image_height = static_cast<int>(image_width / aspect_ratio);
-
-    hittable_list world;
-
     int samples_per_pixel = 100;
     int max_depth = 50;
 
+    // World
+
+    hittable_list world;
+
     point3 lookfrom;
     point3 lookat;
-    vec3 vup(0,1,0);
     auto vfov = 40.0;
-    auto aperture = 0.0;
-    auto dist_to_focus = 10.0;
     color background(0,0,0);
 
     switch (0) {
@@ -422,14 +423,22 @@ int main() {
             break;
     }
 
-    std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
+    // Camera
+
+    vec3 vup(0,1,0);
+    auto aperture = 0.0;
+    auto dist_to_focus = 10.0;
 
     camera cam(lookfrom, lookat, vup, vfov, aspect_ratio, aperture, dist_to_focus, 0.0, 1.0);
 
+    // Render
+
+    std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
+
     for (int j = image_height-1; j >= 0; --j) {
         std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
         for (int i = 0; i < image_width; ++i) {
-            color pixel_color;
+            color pixel_color(0,0,0);
             for (int s = 0; s < samples_per_pixel; ++s) {
                 auto u = (i + random_double()) / (image_width-1);
                 auto v = (j + random_double()) / (image_height-1);

src/TheNextWeek/material.h

@@ -18,7 +18,7 @@
 
 
 double schlick(double cosine, double ref_idx) {
-    double r0 = (1-ref_idx) / (1+ref_idx);
+    auto r0 = (1-ref_idx) / (1+ref_idx);
     r0 = r0*r0;
     return r0 + (1-r0)*pow((1 - cosine),5);
 }
@@ -36,6 +36,44 @@ class material  {
 };
 
 
+class lambertian : public material {
+    public:
+        lambertian(const color& a) : albedo(make_shared<solid_color>(a)) {}
+        lambertian(shared_ptr<texture> a) : albedo(a) {}
+
+        virtual bool scatter(
+            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
+        ) const {
+            vec3 scatter_direction = rec.normal + random_unit_vector();
+            scattered = ray(rec.p, scatter_direction, r_in.time());
+            attenuation = albedo->value(rec.u, rec.v, rec.p);
+            return true;
+        }
+
+    public:
+        shared_ptr<texture> albedo;
+};
+
+
+class metal : public material {
+    public:
+        metal(const color& a, double f) : albedo(a), fuzz(f < 1 ? f : 1) {}
+
+        virtual bool scatter(
+            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
+        ) const {
+            vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
+            scattered = ray(rec.p, reflected + fuzz*random_in_unit_sphere(), r_in.time());
+            attenuation = albedo;
+            return (dot(scattered.direction(), rec.normal) > 0);
+        }
+
+    public:
+        color albedo;
+        double fuzz;
+};
+
+
 class dielectric : public material {
     public:
         dielectric(double ri) : ref_idx(ri) {}
@@ -44,20 +82,15 @@ class dielectric : public material {
             const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
         ) const {
             attenuation = color(1.0, 1.0, 1.0);
-            double etai_over_etat = (rec.front_face) ? (1.0 / ref_idx) : (ref_idx);
+            double etai_over_etat = (rec.front_face) ? (1.0 / ref_idx) : ref_idx;
 
             vec3 unit_direction = unit_vector(r_in.direction());
             double cos_theta = fmin(dot(-unit_direction, rec.normal), 1.0);
             double sin_theta = sqrt(1.0 - cos_theta*cos_theta);
-            if (etai_over_etat * sin_theta > 1.0 ) {
-                vec3 reflected = reflect(unit_direction, rec.normal);
-                scattered = ray(rec.p, reflected, r_in.time());
-                return true;
-            }
 
-            double reflect_prob = schlick(cos_theta, etai_over_etat);
-            if (random_double() < reflect_prob)
-            {
+            if (  (etai_over_etat * sin_theta > 1.0)
+               || (random_double() < schlick(cos_theta, etai_over_etat))
+               ) {
                 vec3 reflected = reflect(unit_direction, rec.normal);
                 scattered = ray(rec.p, reflected, r_in.time());
                 return true;
@@ -110,42 +143,4 @@ class isotropic : public material {
 };
 
 
-class lambertian : public material {
-    public:
-        lambertian(const color& a) : albedo(make_shared<solid_color>(a)) {}
-        lambertian(shared_ptr<texture> a) : albedo(a) {}
-
-        virtual bool scatter(
-            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
-        ) const {
-            vec3 scatter_direction = rec.normal + random_unit_vector();
-            scattered = ray(rec.p, scatter_direction, r_in.time());
-            attenuation = albedo->value(rec.u, rec.v, rec.p);
-            return true;
-        }
-
-    public:
-        shared_ptr<texture> albedo;
-};
-
-
-class metal : public material {
-    public:
-        metal(const color& a, double f) : albedo(a), fuzz(f < 1 ? f : 1) {}
-
-        virtual bool scatter(
-            const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered
-        ) const {
-            vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
-            scattered = ray(rec.p, reflected + fuzz*random_in_unit_sphere(), r_in.time());
-            attenuation = albedo;
-            return (dot(scattered.direction(), rec.normal) > 0);
-        }
-
-    public:
-        color albedo;
-        double fuzz;
-};
-
-
 #endif

src/TheNextWeek/sphere.h

@@ -49,7 +49,7 @@ bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) cons
     if (discriminant > 0) {
         auto root = sqrt(discriminant);
 
-        auto temp = (-half_b - root)/a;
+        auto temp = (-half_b - root) / a;
         if (temp < t_max && temp > t_min) {
             rec.t = temp;
             rec.p = r.at(rec.t);
@@ -60,7 +60,7 @@ bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) cons
             return true;
         }
 
-        temp = (-half_b + root)/a;
+        temp = (-half_b + root) / a;
         if (temp < t_max && temp > t_min) {
             rec.t = temp;
             rec.p = r.at(rec.t);
@@ -75,4 +75,5 @@ bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) cons
     return false;
 }
 
+
 #endif