add example

examples/CMakeLists.txt

@@ -1,4 +1,13 @@
 
+add_executable(visitors visitors.cpp)
+target_link_libraries(visitors PUBLIC bonxai_core)
+
+###############################################
+add_executable(test_serialization test_serialization.cpp)
+target_link_libraries(test_serialization PUBLIC bonxai_core)
+
+###############################################
+
 add_executable(bonxai_map_playground bonxai_map_playground.cpp)
 
 target_include_directories(bonxai_map_playground PUBLIC ${octomap_INCLUDE_DIRS})
@@ -8,8 +17,3 @@ target_link_libraries(bonxai_map_playground PUBLIC
  ${OCTOMAP_LIBRARIES}
  )
 
-###############################################
-add_executable(test_serialization test_serialization.cpp)
-
-target_link_libraries(test_serialization PUBLIC
-    bonxai_core)

examples/visitors.cpp

@@ -0,0 +1,45 @@
+#include "bonxai/bonxai.hpp"
+#include <iostream>
+
+int main()
+{
+  const double VOXEL_RESOLUTION = 0.1;
+
+  Bonxai::VoxelGrid<int> grid(VOXEL_RESOLUTION);
+  // to modify a grid, we need a mutable accessor
+  auto accessor = grid.createAccessor();
+
+  int count = 0;
+  for (double x = -0.5; x < 0.5; x += VOXEL_RESOLUTION)
+  {
+    for (double y = -0.5; y < 0.5; y += VOXEL_RESOLUTION)
+    {
+      for (double z = -0.5; z < 0.5; z += VOXEL_RESOLUTION)
+      {
+        accessor.setValue(grid.posToCoord(x, y, z), count++);
+      }
+    }
+  }
+
+  // To iterate throught all the cells, we can use visitors.
+  auto mutableVisitor = [](int& value, const Bonxai::CoordT&)
+  {
+    value = 1;
+  };
+  auto& gridRef = grid;
+  gridRef.forEachCell(mutableVisitor);
+
+  // Const version of the visitor
+  auto constVisitor = [](const int& value, const Bonxai::CoordT&)
+  {
+    if(value != 1)
+    {
+      throw std::runtime_error("unexpected");
+    }
+  };
+  const auto& gridConstRef = grid;
+  gridConstRef.forEachCell(constVisitor);
+
+  std::cout << "DONE\n";
+  return 0;
+}