Add examples: nanoflann_gui_example_R3_knn and nanoflann_gui_example_…

…R3_radius

CHANGELOG.md

@@ -1,6 +1,9 @@
 nanoflann 1.5.1: UNRELEASED
  * **API changes:**
    - Add missing `SearchParameters` argument to `KDTreeSingleIndexDynamicAdaptor_::knnSearch()` ([PR#213](https://github.com/jlblancoc/nanoflann/pull/213) by [ManosPapadakis95](https://github.com/ManosPapadakis95)).
+ * **Other changes**:
+   - Add examples: `nanoflann_gui_example_R3_knn` and `nanoflann_gui_example_R3_radius`
+
 
 nanoflann 1.5.0: Released Jun 16, 2023
  * **API changes:**

examples/examples_gui/nanoflann_gui_example_R3/CMakeLists.txt

@@ -4,15 +4,22 @@ project(nanoflann_gui_example_R3)
 find_package(nanoflann REQUIRED)
 find_package(mrpt-gui REQUIRED)
 
-add_executable(${PROJECT_NAME} ${PROJECT_NAME}.cpp)
+add_executable(${PROJECT_NAME}_radius ${PROJECT_NAME}.cpp)
+add_executable(${PROJECT_NAME}_knn ${PROJECT_NAME}.cpp)
+
+target_compile_definitions(${PROJECT_NAME}_radius PRIVATE USE_RADIUS_SEARCH)
+target_compile_definitions(${PROJECT_NAME}_knn PRIVATE USE_KNN_SEARCH)
 
 # optimized build:
 if (CMAKE_COMPILER_IS_GNUCXX)
-	target_compile_options(${PROJECT_NAME} PRIVATE -O2 -mtune=native)
+	target_compile_options(${PROJECT_NAME}_radius PRIVATE -O2 -mtune=native)
+	target_compile_options(${PROJECT_NAME}_knn PRIVATE -O2 -mtune=native)
 endif()
 
 # Make sure the include path is used:
-target_link_libraries(${PROJECT_NAME} nanoflann::nanoflann mrpt::gui)
+target_link_libraries(${PROJECT_NAME}_radius nanoflann::nanoflann mrpt::gui)
+target_link_libraries(${PROJECT_NAME}_knn nanoflann::nanoflann mrpt::gui)
 
 # for this example to find "../utils.h"
-target_include_directories(${PROJECT_NAME} PRIVATE ".")
+target_include_directories(${PROJECT_NAME}_radius PRIVATE ".")
+target_include_directories(${PROJECT_NAME}_knn PRIVATE ".")

examples/examples_gui/nanoflann_gui_example_R3/nanoflann_gui_example_R3.cpp

@@ -79,7 +79,13 @@ void kdtree_demo(const size_t N)
         glFoundPts->setColor_u8(0x00, 0x00, 0xff, 0x80);
         scene->insert(glFoundPts);
 
+#if defined(USE_RADIUS_SEARCH)
         glQuerySphere->setColor_u8(0xe0, 0xe0, 0xe0, 0x30);
+        glQuerySphere->enableDrawSolid3D(true);
+#else
+        glQuerySphere->setColor_u8(0xe0, 0xe0, 0xe0, 0x30);
+        glQuerySphere->enableDrawSolid3D(false);
+#endif
         scene->insert(glQuerySphere);
     }
 
@@ -99,40 +105,69 @@ void kdtree_demo(const size_t N)
 
     auto& rng = mrpt::random::getRandomGenerator();
 
-    // Declare here to avoid reallocations:
+// Declare here to avoid reallocations:
+#if defined(USE_RADIUS_SEARCH)
     std::vector<nanoflann::ResultItem<size_t, double>> indicesDists;
+#elif defined(USE_KNN_SEARCH)
+    std::vector<size_t> indices;
+    std::vector<double> distances;
+#else
+#error Expected either KNN or radius search build flag!
+#endif
 
     // Loop: different searches until the window is closed:
     while (win.isOpen())
     {
         // Unsorted radius search:
+#if defined(USE_RADIUS_SEARCH)
         const double radius   = rng.drawUniform(0.1, maxRangeXY * 0.5);
         const double sqRadius = radius * radius;
-
+#else
+        const size_t nnToSearch = (rng.drawUniform32bit() % 10) + 1;
+#endif
         const double queryPt[3] = {
             rng.drawUniform(-0.3, maxRangeXY + 0.3),
             rng.drawUniform(-0.3, maxRangeXY + 0.3),
             rng.drawUniform(-0.3, maxRangeZ + 0.3)};
 
         mrpt::system::CTimeLoggerEntry tle2(profiler, "query");
 
+#if defined(USE_RADIUS_SEARCH)
         indicesDists.clear();
         nanoflann::RadiusResultSet<double, size_t> resultSet(
             sqRadius, indicesDists);
+        index.findNeighbors(resultSet, queryPt);
+#else
+        nanoflann::KNNResultSet<double, size_t> resultSet(nnToSearch);
+        indices.resize(nnToSearch);
+        distances.resize(nnToSearch);
+        resultSet.init(indices.data(), distances.data());
 
         index.findNeighbors(resultSet, queryPt);
 
+        indices.resize(resultSet.size());
+        distances.resize(resultSet.size());
+
+        const double worstDist = std::sqrt(resultSet.worstDist());
+#endif
         tle2.stop();
 
         std::cout << "\nQuery point: (" << queryPt[0] << "," << queryPt[1]
                   << "," << queryPt[2] << ") => " << resultSet.size()
                   << " results.\n";
+
         if (!resultSet.empty())
         {
+#if defined(USE_RADIUS_SEARCH)
             nanoflann::ResultItem<size_t, double> worstPair =
                 resultSet.worst_item();
             std::cout << "Worst pair: idx=" << worstPair.first
                       << " dist=" << std::sqrt(worstPair.second) << std::endl;
+#else
+            std::cout << "nnToSearch=" << nnToSearch
+                      << " actual found=" << indices.size()
+                      << " Worst found dist=" << worstDist << std::endl;
+#endif
         }
 
         // Color results:
@@ -143,12 +178,19 @@ void kdtree_demo(const size_t N)
             glQueryPt->insertPoint(queryPt[0], queryPt[1], queryPt[2]);
 
             glQuerySphere->setLocation(queryPt[0], queryPt[1], queryPt[2]);
+#if defined(USE_RADIUS_SEARCH)
             glQuerySphere->setRadius(radius);
-
+#else
+            glQuerySphere->setRadius(worstDist);
+#endif
             glFoundPts->clear();
-            for (const auto& ptIdx : indicesDists)
+#if defined(USE_RADIUS_SEARCH)
+            for (const auto& [idx, dist] : indicesDists)
+#else
+            for (const auto idx : indices)
+#endif
             {
-                const auto& pt = cloud.pts.at(ptIdx.first);
+                const auto& pt = cloud.pts.at(idx);
                 glFoundPts->insertPoint(pt.x, pt.y, pt.z);
             }