Fix & simplify hittable_list::bounding_box()

Resolves #435

Author: hollasch

CHANGELOG.md

@@ -1,6 +1,13 @@
 Change Log -- Ray Tracing in One Weekend
 ====================================================================================================
 
+----------------------------------------------------------------------------------------------------
+# v3.0.2 (in progress)
+
+### _The Next Week_
+- Fix `shared_ptr` dereference and simplify code in `hittable_list::bounding_box()` (#435)
+
+
 ----------------------------------------------------------------------------------------------------
 # v3.0.1 (2020-03-31)
 

books/RayTracingTheNextWeek.html

@@ -663,17 +663,12 @@
         if (objects.empty()) return false;
 
         aabb temp_box;
-        bool first_true = objects[0]->bounding_box(t0, t1, temp_box);
-
-        if (!first_true)
-            return false;
-
-        output_box = temp_box;
+        bool first_box = true;
 
         for (const auto& object : objects) {
-            if (!objects[i]->bounding_box(t0, t1, temp_box))
-                return false;
-            output_box = surrounding_box(output_box, temp_box);
+            if (!object->bounding_box(t0, t1, temp_box)) return false;
+            output_box = first_box ? temp_box : surrounding_box(output_box, temp_box);
+            first_box = false;
         }
 
         return true;

src/TheNextWeek/hittable_list.h

@@ -55,17 +55,12 @@ bool hittable_list::bounding_box(double t0, double t1, aabb& output_box) const {
     if (objects.empty()) return false;
 
     aabb temp_box;
-    bool first_true = objects[0]->bounding_box(t0, t1, temp_box);
-
-    if (!first_true)
-        return false;
-
-    output_box = temp_box;
+    bool first_box = true;
 
     for (const auto& object : objects) {
-        if (!object->bounding_box(t0, t1, temp_box))
-            return false;
-        output_box = surrounding_box(output_box, temp_box);
+        if (!object->bounding_box(t0, t1, temp_box)) return false;
+        output_box = first_box ? temp_box : surrounding_box(output_box, temp_box);
+        first_box = false;
     }
 
     return true;