add example for almost coplanar remeshing

Polygon_mesh_processing/doc/Polygon_mesh_processing/examples.txt

@@ -41,5 +41,6 @@
 \example Polygon_mesh_processing/triangulate_faces_split_visitor_example.cpp
 \example Polygon_mesh_processing/hausdorff_bounded_error_distance_example.cpp
 \example Polygon_mesh_processing/cc_compatible_orientations.cpp
-\example Polygon_mesh_processing/decimation_planar_patches.cpp
+\example Polygon_mesh_processing/remesh_planar_patches.cpp
+\example Polygon_mesh_processing/remesh_almost_planar_patches.cpp
 */

Polygon_mesh_processing/examples/Polygon_mesh_processing/CMakeLists.txt

@@ -19,7 +19,7 @@ create_single_source_cgal_program("point_inside_example.cpp")
 create_single_source_cgal_program("triangulate_faces_example.cpp")
 create_single_source_cgal_program("triangulate_faces_split_visitor_example.cpp")
 create_single_source_cgal_program("connected_components_example.cpp")
-create_single_source_cgal_program("decimation_planar_patches.cpp")
+create_single_source_cgal_program("remesh_planar_patches.cpp")
 create_single_source_cgal_program( "face_filtered_graph_example.cpp")
 create_single_source_cgal_program("orient_polygon_soup_example.cpp")
 create_single_source_cgal_program("triangulate_polyline_example.cpp")
@@ -71,6 +71,8 @@ if(TARGET CGAL::Eigen3_support)
   target_link_libraries(mesh_smoothing_example PUBLIC CGAL::Eigen3_support)
   create_single_source_cgal_program("delaunay_remeshing_example.cpp")
   target_link_libraries(delaunay_remeshing_example PUBLIC CGAL::Eigen3_support)
+  create_single_source_cgal_program("remesh_almost_planar_patches.cpp")
+  target_link_libraries(remesh_almost_planar_patches PUBLIC CGAL::Eigen3_support)
 else()
   message(STATUS "NOTICE: Examples that use Eigen will not be compiled.")
 endif()

Polygon_mesh_processing/examples/Polygon_mesh_processing/remesh_almost_planar_patches.cpp

@@ -0,0 +1,66 @@
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Surface_mesh.h>
+
+#include <CGAL/Polygon_mesh_processing/remesh_planar_patches.h>
+#include <CGAL/Polygon_mesh_processing/region_growing.h>
+#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
+#include <CGAL/Polygon_mesh_processing/random_perturbation.h>
+
+#include <boost/property_map/vector_property_map.hpp>
+
+#include <iostream>
+#include <fstream>
+
+
+typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
+typedef Kernel::Point_3 Point_3;
+typedef CGAL::Surface_mesh<Kernel::Point_3> Surface_mesh;
+
+namespace PMP = CGAL::Polygon_mesh_processing;
+
+int main()
+{
+  Surface_mesh sm;
+  CGAL::IO::read_polygon_mesh(CGAL::data_file_path("meshes/fandisk.off"), sm);
+
+  //apply a perturbation to input vertices so that points are no longer coplanar
+  PMP::random_perturbation(sm, 0.001);
+
+  // declare vectors to store mesh properties
+  std::vector<std::size_t> region_ids(num_faces(sm));
+  std::vector<std::size_t> corner_id_map(num_vertices(sm), -1); // corner status of vertices
+  std::vector<bool> ecm(num_edges(sm), false); // mark edges at the boundary of regions
+  boost::vector_property_map<CGAL::Epick::Vector_3> normal_map; // normal of the supporting planes of the regions detected
+
+  // detect planar regions in the mesh
+  std::size_t nb_regions =
+    PMP::region_growing_of_planes_on_faces(sm,
+                                           CGAL::make_random_access_property_map(region_ids),
+                                           CGAL::parameters::cosine_of_maximum_angle(0.98).
+                                                             region_primitive_map(normal_map).
+                                                             maximum_distance(0.011));
+
+  // detect corner vertices on the boundary of planar regions
+  std::size_t nb_corners =
+    PMP::detect_corners_of_regions(sm,
+                                   CGAL::make_random_access_property_map(region_ids),
+                                   nb_regions,
+                                   CGAL::make_random_access_property_map(corner_id_map),
+                                   CGAL::parameters::cosine_of_maximum_angle(0.98).
+                                                     maximum_distance(0.011).
+                                                     edge_is_constrained_map(CGAL::make_random_access_property_map(ecm)));
+
+  // run the remeshing algorithm using filled properties
+  Surface_mesh out;
+  PMP::remesh_almost_planar_patches(sm,
+                                    out,
+                                    nb_regions, nb_corners,
+                                    CGAL::make_random_access_property_map(region_ids),
+                                    CGAL::make_random_access_property_map(corner_id_map),
+                                    CGAL::make_random_access_property_map(ecm),
+                                    CGAL::parameters::patch_normal_map(normal_map));
+
+  CGAL::IO::write_polygon_mesh("fandisk_remeshed.off", out);
+
+  return 0;
+}