Merge pull request #517 from RayTracing/fix-489

Update random_scene() in books 1 and 2

Author: hollasch

CHANGELOG.md

@@ -5,11 +5,19 @@ Change Log -- Ray Tracing in One Weekend
 
 ### _In One Weekend_
   - Change: The C++ `<random>` version of `random_double()` no longer depends on `<functional>`
-    header
+    header.
+  - Change: Refactored `random_scene()`. More named intermediate values, sync'ed with source.
+    (#489)
 
 ### _The Next Week_
+  - Fix: Added clarification about updating lambertian variables from `color` to `solid_color`.
+  - Fix: Corrected for-loop indices (they differed from the version in book 1) in `random_scene()`.
   - Fix: Introduce "Texture Coordinates for Spheres" in Chapter 4 to support (u,v) coordinates in
     `hit_record` (#496)
+  - Change: Refactored `random_scene()`. More named intermediate values, sync'ed with version in
+    _In One Weekend_ and with source. Added highlight for update from last version in book 1. (#489)
+  - Change: The C++ `<random>` version of `random_double()` no longer depends on `<functional>`
+    header
 
 
 ----------------------------------------------------------------------------------------------------

books/RayTracingInOneWeekend.html

@@ -2846,41 +2846,45 @@
     hittable_list random_scene() {
         hittable_list world;
 
-        world.add(make_shared<sphere>(
-            point3(0,-1000,0), 1000, make_shared<lambertian>(color(0.5, 0.5, 0.5))));
+        auto ground_material = make_shared<lambertian>(color(0.5, 0.5, 0.5));
+        world.add(make_shared<sphere>(point3(0,-1000,0), 1000, ground_material));
 
-        int i = 1;
         for (int a = -11; a < 11; a++) {
             for (int b = -11; b < 11; b++) {
                 auto choose_mat = random_double();
                 point3 center(a + 0.9*random_double(), 0.2, b + 0.9*random_double());
+
                 if ((center - vec3(4, 0.2, 0)).length() > 0.9) {
+                    shared_ptr<material> sphere_material;
+
                     if (choose_mat < 0.8) {
                         // diffuse
                         auto albedo = color::random() * color::random();
-                        world.add(
-                            make_shared<sphere>(center, 0.2, make_shared<lambertian>(albedo)));
+                        sphere_material = make_shared<lambertian>(albedo);
+                        world.add(make_shared<sphere>(center, 0.2, sphere_material));
                     } else if (choose_mat < 0.95) {
                         // metal
-                        auto albedo = color::random(.5, 1);
-                        auto fuzz = random_double(0, .5);
-                        world.add(
-                            make_shared<sphere>(center, 0.2, make_shared<metal>(albedo, fuzz)));
+                        auto albedo = color::random(0.5, 1);
+                        auto fuzz = random_double(0, 0.5);
+                        sphere_material = make_shared<metal>(albedo, fuzz);
+                        world.add(make_shared<sphere>(center, 0.2, sphere_material));
                     } else {
                         // glass
-                        world.add(make_shared<sphere>(center, 0.2, make_shared<dielectric>(1.5)));
+                        sphere_material = make_shared<dielectric>(1.5);
+                        world.add(make_shared<sphere>(center, 0.2, sphere_material));
                     }
                 }
             }
         }
 
-        world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, make_shared<dielectric>(1.5)));
+        auto material1 = make_shared<dielectric>(1.5);
+        world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, material1));
 
-        world.add(
-            make_shared<sphere>(point3(-4, 1, 0), 1.0, make_shared<lambertian>(color(.4, .2, .1))));
+        auto material2 = make_shared<lambertian>(color(0.4, 0.2, 0.1));
+        world.add(make_shared<sphere>(point3(-4, 1, 0), 1.0, material2));
 
-        world.add(
-            make_shared<sphere>(point3(4, 1, 0), 1.0, make_shared<metal>(color(.7, .6, .5), 0.0)));
+        auto material3 = make_shared<metal>(color(0.7, 0.6, 0.5), 0.0);
+        world.add(make_shared<sphere>(point3(4, 1, 0), 1.0, material3));
 
         return world;
     }

books/RayTracingTheNextWeek.html

@@ -292,40 +292,49 @@
     hittable_list random_scene() {
         hittable_list world;
 
-        world.add(make_shared<sphere>(
-            point3(0,-1000,0), 1000, make_shared<lambertian>(color(0.5, 0.5, 0.5))));
+        auto ground_material = make_shared<lambertian>(color(0.5, 0.5, 0.5));
+        world.add(make_shared<sphere>(point3(0,-1000,0), 1000, ground_material));
 
-        int i = 1;
-        for (int a = -10; a < 10; a++) {
-            for (int b = -10; b < 10; b++) {
+        for (int a = -11; a < 11; a++) {
+            for (int b = -11; b < 11; b++) {
                 auto choose_mat = random_double();
                 point3 center(a + 0.9*random_double(), 0.2, b + 0.9*random_double());
-                if ((center - vec3(4, .2, 0)).length() > 0.9) {
+
+                if ((center - vec3(4, 0.2, 0)).length() > 0.9) {
+                    shared_ptr<material> sphere_material;
+
                     if (choose_mat < 0.8) {
                         // diffuse
                         auto albedo = color::random() * color::random();
+                        sphere_material = make_shared<lambertian>(albedo);
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
+                        auto center2 = center + vec3(0, random_double(0,.5), 0);
                         world.add(make_shared<moving_sphere>(
-                            center, center + vec3(0, random_double(0,.5), 0), 0.0, 1.0, 0.2,
-                            make_shared<lambertian>(albedo)));
+                            center, center2, 0.0, 1.0, 0.2, sphere_material));
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
                     } else if (choose_mat < 0.95) {
                         // metal
-                        auto albedo = color::random(.5, 1);
-                        auto fuzz = random_double(0, .5);
-                        world.add(
-                            make_shared<sphere>(center, 0.2, make_shared<metal>(albedo, fuzz)));
+                        auto albedo = color::random(0.5, 1);
+                        auto fuzz = random_double(0, 0.5);
+                        sphere_material = make_shared<metal>(albedo, fuzz);
+                        world.add(make_shared<sphere>(center, 0.2, sphere_material));
                     } else {
                         // glass
-                        world.add(make_shared<sphere>(center, 0.2, make_shared<dielectric>(1.5)));
+                        sphere_material = make_shared<dielectric>(1.5);
+                        world.add(make_shared<sphere>(center, 0.2, sphere_material));
                     }
                 }
             }
         }
 
-        world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, make_shared<dielectric>(1.5)));
-        world.add(make_shared<sphere>(
-            point3(-4, 1, 0), 1.0, make_shared<lambertian>(color(0.4, 0.2, 0.1))));
-        world.add(make_shared<sphere>(
-            point3(4, 1, 0), 1.0, make_shared<metal>(color(0.7, 0.6, 0.5), 0.0)));
+        auto material1 = make_shared<dielectric>(1.5);
+        world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, material1));
+
+        auto material2 = make_shared<lambertian>(color(0.4, 0.2, 0.1));
+        world.add(make_shared<sphere>(point3(-4, 1, 0), 1.0, material2));
+
+        auto material3 = make_shared<metal>(color(0.7, 0.6, 0.5), 0.0);
+        world.add(make_shared<sphere>(point3(4, 1, 0), 1.0, material3));
 
         return world;
     }
@@ -1053,7 +1062,7 @@
 </div>
 
 <div class='together'>
-Where you used to have
+Where you used to have code like this:
 
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
         ...make_shared<lambertian>(color(0.5, 0.5, 0.5))
@@ -1066,6 +1075,8 @@
         ...make_shared<lambertian>(make_shared<solid_color>(0.5, 0.5, 0.5))
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [lam-textured]: <kbd>[main.cc]</kbd> Lambertian material with texture]
+
+Update all three occurrences of lambertian in the `random_scene()` function in `main.cc`.
 </div>
 
 
@@ -1106,7 +1117,8 @@
 
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
     auto checker = make_shared<checker_texture>(
-        make_shared<solid_color>(0.2, 0.3, 0.1), make_shared<solid_color>(0.9, 0.9, 0.9)
+        make_shared<solid_color>(0.2, 0.3, 0.1),
+        make_shared<solid_color>(0.9, 0.9, 0.9)
     );
 
     world.add(make_shared<sphere>(point3(0,-1000,0), 1000, make_shared<lambertian>(checker)));
@@ -1130,7 +1142,8 @@
         hittable_list objects;
 
         auto checker = make_shared<checker_texture>(
-            make_shared<solid_color>(0.2, 0.3, 0.1), make_shared<solid_color>(0.9, 0.9, 0.9)
+            make_shared<solid_color>(0.2, 0.3, 0.1),
+            make_shared<solid_color>(0.9, 0.9, 0.9)
         );
 
         objects.add(make_shared<sphere>(point3(0,-10, 0), 10, make_shared<lambertian>(checker)));

src/InOneWeekend/main.cc

@@ -44,47 +44,45 @@ color ray_color(const ray& r, const hittable& world, int depth) {
 hittable_list random_scene() {
     hittable_list world;
 
-    world.add(
-        make_shared<sphere>(
-            point3(0,-1000,0), 1000, make_shared<lambertian>(color(0.5, 0.5, 0.5)))
-    );
+    auto ground_material = make_shared<lambertian>(color(0.5, 0.5, 0.5));
+    world.add(make_shared<sphere>(point3(0,-1000,0), 1000, ground_material));
 
-    int i = 1;
     for (int a = -11; a < 11; a++) {
         for (int b = -11; b < 11; b++) {
             auto choose_mat = random_double();
             point3 center(a + 0.9*random_double(), 0.2, b + 0.9*random_double());
+
             if ((center - vec3(4, 0.2, 0)).length() > 0.9) {
+                shared_ptr<material> sphere_material;
+
                 if (choose_mat < 0.8) {
                     // diffuse
                     auto albedo = color::random() * color::random();
-                    world.add(
-                        make_shared<sphere>(center, 0.2, make_shared<lambertian>(albedo)));
+                    sphere_material = make_shared<lambertian>(albedo);
+                    world.add(make_shared<sphere>(center, 0.2, sphere_material));
                 } else if (choose_mat < 0.95) {
                     // metal
-                    auto albedo = color::random(.5, 1);
-                    auto fuzz = random_double(0, .5);
-                    world.add(
-                        make_shared<sphere>(center, 0.2, make_shared<metal>(albedo, fuzz)));
+                    auto albedo = color::random(0.5, 1);
+                    auto fuzz = random_double(0, 0.5);
+                    sphere_material = make_shared<metal>(albedo, fuzz);
+                    world.add(make_shared<sphere>(center, 0.2, sphere_material));
                 } else {
                     // glass
-                    world.add(make_shared<sphere>(center, 0.2, make_shared<dielectric>(1.5)));
+                    sphere_material = make_shared<dielectric>(1.5);
+                    world.add(make_shared<sphere>(center, 0.2, sphere_material));
                 }
             }
         }
     }
 
-    world.add(
-        make_shared<sphere>(
-            point3(0, 1, 0), 1.0, make_shared<dielectric>(1.5)));
+    auto material1 = make_shared<dielectric>(1.5);
+    world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, material1));
 
-    world.add(
-        make_shared<sphere>(
-            point3(-4, 1, 0), 1.0, make_shared<lambertian>(color(0.4, 0.2, 0.1))));
+    auto material2 = make_shared<lambertian>(color(0.4, 0.2, 0.1));
+    world.add(make_shared<sphere>(point3(-4, 1, 0), 1.0, material2));
 
-    world.add(
-        make_shared<sphere>(
-            point3(4, 1, 0), 1.0, make_shared<metal>(color(0.7, 0.6, 0.5), 0.0)));
+    auto material3 = make_shared<metal>(color(0.7, 0.6, 0.5), 0.0);
+    world.add(make_shared<sphere>(point3(4, 1, 0), 1.0, material3));
 
     return world;
 }

src/TheNextWeek/main.cc

@@ -57,46 +57,44 @@ hittable_list random_scene() {
 
     world.add(make_shared<sphere>(point3(0,-1000,0), 1000, make_shared<lambertian>(checker)));
 
-    for (int a = -10; a < 10; a++) {
-        for (int b = -10; b < 10; b++) {
+    for (int a = -11; a < 11; a++) {
+        for (int b = -11; b < 11; b++) {
             auto choose_mat = random_double();
             point3 center(a + 0.9*random_double(), 0.2, b + 0.9*random_double());
-            if ((center - vec3(4, .2, 0)).length() > 0.9) {
+
+            if ((center - vec3(4, 0.2, 0)).length() > 0.9) {
+                shared_ptr<material> sphere_material;
+
                 if (choose_mat < 0.8) {
                     // diffuse
                     auto albedo = color::random() * color::random();
+                    sphere_material = make_shared<lambertian>(make_shared<solid_color>(albedo));
+                    auto center2 = center + vec3(0, random_double(0,.5), 0);
                     world.add(make_shared<moving_sphere>(
-                        center, center + vec3(0, random_double(0,.5), 0), 0.0, 1.0, 0.2,
-                        make_shared<lambertian>(make_shared<solid_color>(albedo))
-                    ));
+                        center, center2, 0.0, 1.0, 0.2, sphere_material));
                 } else if (choose_mat < 0.95) {
                     // metal
-                    auto albedo = color::random(.5, 1);
-                    auto fuzz = random_double(0, .5);
-                    world.add(
-                        make_shared<sphere>(center, 0.2, make_shared<metal>(albedo, fuzz)));
+                    auto albedo = color::random(0.5, 1);
+                    auto fuzz = random_double(0, 0.5);
+                    sphere_material = make_shared<metal>(albedo, fuzz);
+                    world.add(make_shared<sphere>(center, 0.2, sphere_material));
                 } else {
                     // glass
-                    world.add(make_shared<sphere>(center, 0.2, make_shared<dielectric>(1.5)));
+                    sphere_material = make_shared<dielectric>(1.5);
+                    world.add(make_shared<sphere>(center, 0.2, sphere_material));
                 }
             }
         }
     }
 
-    world.add(make_shared<sphere>(point3(0,1,0), 1.0, make_shared<dielectric>(1.5)));
+    auto material1 = make_shared<dielectric>(1.5);
+    world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, material1));
 
-    world.add(
-        make_shared<sphere>(
-            point3(-4,1,0), 1.0,
-            make_shared<lambertian>(make_shared<solid_color>(0.4, 0.2, 0.1))
-        )
-    );
+    auto material2 = make_shared<lambertian>(make_shared<solid_color>(color(0.4, 0.2, 0.1)));
+    world.add(make_shared<sphere>(point3(-4, 1, 0), 1.0, material2));
 
-    world.add(
-        make_shared<sphere>(
-            point3(4,1,0), 1.0, make_shared<metal>(color(0.7, 0.6, 0.5), 0.0)
-        )
-    );
+    auto material3 = make_shared<metal>(color(0.7, 0.6, 0.5), 0.0);
+    world.add(make_shared<sphere>(point3(4, 1, 0), 1.0, material3));
 
     return hittable_list(make_shared<bvh_node>(world, 0.0, 1.0));
 }
@@ -106,7 +104,8 @@ hittable_list two_spheres() {
     hittable_list objects;
 
     auto checker = make_shared<checker_texture>(
-        make_shared<solid_color>(0.2, 0.3, 0.1), make_shared<solid_color>(0.9, 0.9, 0.9)
+        make_shared<solid_color>(0.2, 0.3, 0.1),
+        make_shared<solid_color>(0.9, 0.9, 0.9)
     );
 
     objects.add(make_shared<sphere>(point3(0,-10, 0), 10, make_shared<lambertian>(checker)));