img-1.15

Author: hollasch

src/InOneWeekend/main.cc

@@ -40,9 +40,9 @@ int main() {
     hittable_list world;
 
     auto material_ground = make_shared<lambertian>(color(0.8, 0.8, 0.0));
-    auto material_center = make_shared<dielectric>(1.5);
+    auto material_center = make_shared<lambertian>(color(0.1, 0.2, 0.5));
     auto material_left   = make_shared<dielectric>(1.5);
-    auto material_right  = make_shared<metal>(color(0.8, 0.6, 0.2), 1.0);
+    auto material_right  = make_shared<metal>(color(0.8, 0.6, 0.2), 0.0);
 
     world.add(make_shared<sphere>(point3( 0.0, -100.5, -1.0), 100.0, material_ground));
     world.add(make_shared<sphere>(point3( 0.0,    0.0, -1.0),   0.5, material_center));

src/InOneWeekend/material.h

@@ -60,19 +60,23 @@ 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;
-            if (rec.front_face) {
-                etai_over_etat = 1.0 / ref_idx;
-            } else {
-                etai_over_etat = 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);
+                return true;
+            }
+
             vec3 refracted = refract(unit_direction, rec.normal, etai_over_etat);
             scattered = ray(rec.p, refracted);
             return true;
         }
 
+    public:
         double ref_idx;
 };