Add naive nearest neighbour solver and printouts

Octree/test/Octree/test_nearest_neighbor.cpp

@@ -6,25 +6,69 @@
 #include <CGAL/Octree/IO.h>
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Point_set_3.h>
+#include <CGAL/point_generators_3.h>
+#include <CGAL/squared_distance_3.h>
 
 #include <cassert>
 
 typedef CGAL::Simple_cartesian<double> Kernel;
 typedef Kernel::Point_3 Point;
+typedef Kernel::FT FT;
 typedef CGAL::Point_set_3<Point> Point_set;
 typedef CGAL::Octree::Octree
         <Point_set, typename Point_set::Point_map>
         Octree;
 
-void naive_vs_accelerated() {
+void naive_vs_accelerated(std::size_t dataset_size) {
 
   // Create a dataset
+  Point_set points;
+  CGAL::Random_points_in_cube_3<Point> generator;
+  points.reserve(dataset_size);
+  for (std::size_t i = 0; i < dataset_size; ++i)
+    points.insert(*(generator++));
 
-  // Choose a random point
+  // Choose another random point from the same bounds as the dataset
+  Point random_point = *(generator++);
 
   // Use the naive algorithm to find the nearest point in the dataset
+  Point naive_nearest = *points.points().begin();
+  {
+    FT distance_nearest = std::numeric_limits<FT>::max();
+    for (auto &p : points.points()) {
+
+      FT distance_current = CGAL::squared_distance(p, random_point);
+      if (distance_current < distance_nearest) {
+
+        distance_nearest = distance_current;
+        naive_nearest = p;
+      }
+    }
+  }
+
+  std::cout << "Naive --> "
+            << "Closest point to "
+            << "(" << random_point << ") "
+            << "is "
+            << "(" << naive_nearest << ") "
+            << "at a distance^2 of "
+            << CGAL::squared_distance(naive_nearest, random_point)
+            << std::endl;
 
   // Do the same using the octree
+  Point octree_nearest = *generator;
+  {
+
+  }
+
+  std::cout << "Octree --> "
+            << "Closest point to "
+            << "(" << random_point << ") "
+            << "is "
+            << "(" << octree_nearest << ") "
+            << "at a distance^2 of "
+            << CGAL::squared_distance(octree_nearest, random_point)
+            << std::endl;
 
   // Check that they produce the same answer
 
@@ -34,7 +78,10 @@ void naive_vs_accelerated() {
 
 int main(void) {
 
-  naive_vs_accelerated();
+  naive_vs_accelerated(100);
+  naive_vs_accelerated(1000);
+  naive_vs_accelerated(10000);
+  naive_vs_accelerated(100000);
 
   return EXIT_SUCCESS;
 }