constant_medium.h: update to latest

We fixed the `constant_medium::hit()` function in TheNextWeek, but
neglected to update the same file in TheRestOfYourLife.

src/TheRestOfYourLife/constant_medium.h

@@ -1,7 +1,7 @@
 #ifndef CONSTANT_MEDIUM_H
 #define CONSTANT_MEDIUM_H
 //==================================================================================================
-// Written in 2016 by Peter Shirley <ptrshrl@gmail.com>
+// Originally written in 2016 by Peter Shirley <ptrshrl@gmail.com>
 //
 // To the extent possible under law, the author(s) have dedicated all copyright and related and
 // neighboring rights to this software to the public domain worldwide. This software is distributed
@@ -12,45 +12,63 @@
 //==================================================================================================
 
 #include "hittable.h"
+#include "material.h"
 #include "random.h"
+#include "texture.h"
 
 #include <float.h>
 
 
 class constant_medium : public hittable  {
     public:
-        constant_medium(hittable *b, double d, texture *a) : boundary(b), density(d) { phase_function = new isotropic(a); }
+        constant_medium(hittable *b, double d, texture *a) : boundary(b), density(d) {
+            phase_function = new isotropic(a);
+        }
         virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const;
-        virtual bool bounding_box(double t0, double t1, aabb& box) const { 
-            return boundary->bounding_box(t0, t1, box); }
+        virtual bool bounding_box(double t0, double t1, aabb& box) const {
+            return boundary->bounding_box(t0, t1, box);
+        }
         hittable *boundary;
         double density;
         material *phase_function;
 };
 
+
 bool constant_medium::hit(const ray& r, double t_min, double t_max, hit_record& rec) const {
-    bool db = (random_double() < 0.00001);
-    db = false;
+
+    // Print occasional samples when debugging. To enable, set enableDebug true.
+    const bool enableDebug = false;
+    bool debugging = enableDebug && random_double() < 0.00001;
+
     hit_record rec1, rec2;
-    if (boundary->hit(r, -FLT_MAX, FLT_MAX, rec1)) { 
+
+    if (boundary->hit(r, -FLT_MAX, FLT_MAX, rec1)) {
         if (boundary->hit(r, rec1.t+0.0001, FLT_MAX, rec2)) {
-    if (db) std::cerr << "\nt0 t1 " << rec1.t << " " << rec2.t << "\n";
-            if (rec1.t < t_min)
-                rec1.t = t_min;
-            if (rec2.t > t_max)
-                rec2.t = t_max;
+
+            if (debugging) std::cerr << "\nt0 t1 " << rec1.t << " " << rec2.t << '\n';
+
+            if (rec1.t < t_min) rec1.t = t_min;
+            if (rec2.t > t_max) rec2.t = t_max;
+
             if (rec1.t >= rec2.t)
                 return false;
             if (rec1.t < 0)
                 rec1.t = 0;
-            auto distance_inside_boundary = (rec2.t - rec1.t)*r.direction().length();
-            auto hit_distance = -(1/density)*log(random_double()); 
+
+            auto distance_inside_boundary = (rec2.t - rec1.t) * r.direction().length();
+            auto hit_distance = -(1/density) * log(random_double());
+
             if (hit_distance < distance_inside_boundary) {
-            if (db) std::cerr << "hit_distance = " <<  hit_distance << "\n";
-                rec.t = rec1.t + hit_distance / r.direction().length(); 
-            if (db) std::cerr << "rec.t = " <<  rec.t << "\n";
+
+                rec.t = rec1.t + hit_distance / r.direction().length();
                 rec.p = r.point_at_parameter(rec.t);
-            if (db) std::cerr << "rec.p = " <<  rec.p << "\n";
+
+                if (debugging) {
+                    std::cerr << "hit_distance = " <<  hit_distance << '\n'
+                              << "rec.t = " <<  rec.t << '\n'
+                              << "rec.p = " <<  rec.p << '\n';
+                }
+
                 rec.normal = vec3(1,0,0);  // arbitrary
                 rec.mat_ptr = phase_function;
                 return true;