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improve example

This commit is contained in:
Sébastien Loriot 2022-04-07 17:30:40 +02:00
parent c253a64361
commit 086476bc30
1 changed files with 16 additions and 15 deletions
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31
Polygon_mesh_processing/examples/Polygon_mesh_processing/cc_compatible_orientations.cpp
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@ -8,8 +8,7 @@
#include <iostream> #include <iostream>
#include <string> #include <string>
#include <algorithm> #include <cstdlib>
#include <random>
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel; typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::Point_3 Point; typedef Kernel::Point_3 Point;
@ -19,14 +18,11 @@ typedef CGAL::Surface_mesh<Point> Mesh;
namespace PMP = CGAL::Polygon_mesh_processing; namespace PMP = CGAL::Polygon_mesh_processing;
int main()
{
// create a mesh with many connected connected components that should // create a mesh with many connected connected components that should
// be reoriented to define a valid closed mesh // be reoriented to define a valid closed mesh
void create_mesh_with_cc_to_orient(Mesh& mesh)
{
const std::string filename = CGAL::data_file_path("meshes/elephant.off"); const std::string filename = CGAL::data_file_path("meshes/elephant.off");
Mesh mesh;
CGAL::IO::read_polygon_mesh(filename, mesh); CGAL::IO::read_polygon_mesh(filename, mesh);
// turn the mesh into a triangle soup, duplicating all the vertices and shuffling orientations // turn the mesh into a triangle soup, duplicating all the vertices and shuffling orientations
@ -34,8 +30,6 @@ int main()
std::vector< std::array<std::size_t, 3> > triangles; std::vector< std::array<std::size_t, 3> > triangles;
triangles.reserve(faces(mesh).size()); triangles.reserve(faces(mesh).size());
points.reserve(3*triangles.size()); points.reserve(3*triangles.size());
std::random_device rd;
std::mt19937 g(rd());
for (Mesh::Face_index f : mesh.faces()) for (Mesh::Face_index f : mesh.faces())
{ {
Mesh::Halfedge_index h = mesh.halfedge(f); Mesh::Halfedge_index h = mesh.halfedge(f);
@ -44,31 +38,38 @@ int main()
points.push_back(mesh.point(target(h,mesh))); points.push_back(mesh.point(target(h,mesh)));
points.push_back(mesh.point(target(mesh.next(h),mesh))); points.push_back(mesh.point(target(mesh.next(h),mesh)));
triangles.push_back( {s, s+1, s+2} ); triangles.push_back( {s, s+1, s+2} );
std::shuffle(triangles.back().begin(), triangles.back().end(), g); if (std::rand() % 2 == 0)
std::swap(triangles.back()[0], triangles.back()[1]);
} }
// load the soup into the mesh; // load the soup into the mesh;
mesh.clear(); mesh.clear();
PMP::polygon_soup_to_polygon_mesh(points, triangles, mesh); PMP::polygon_soup_to_polygon_mesh(points, triangles, mesh);
CGAL::IO::write_polygon_mesh("soup.off", mesh, CGAL::parameters::stream_precision(17)); }
// determine face orientations to be reversed to create compatibility int main()
{
Mesh mesh;
create_mesh_with_cc_to_orient(mesh);
CGAL::IO::write_polygon_mesh("to_orient.off", mesh, CGAL::parameters::stream_precision(17));
// determine face orientations to be reversed to create compatibility
auto fbm = mesh.add_property_map<Mesh::Face_index, bool>("fbm", false).first; auto fbm = mesh.add_property_map<Mesh::Face_index, bool>("fbm", false).first;
bool is_orientable = PMP::connected_components_compatible_orientations(mesh, fbm); bool is_orientable = PMP::connected_components_compatible_orientations(mesh, fbm);
assert(is_orientable); assert(is_orientable);
// reverse orientation of faces with bit 1 // reverse orientation of faces with bit 1
std::vector<Mesh::Face_index> faces_to_reverse; std::vector<Mesh::Face_index> faces_to_reverse;
for (Mesh::Face_index f : mesh.faces()) for (Mesh::Face_index f : mesh.faces())
if (get(fbm, f)) if (get(fbm, f))
faces_to_reverse.push_back(f); faces_to_reverse.push_back(f);
PMP::reverse_face_orientations(faces_to_reverse, mesh); PMP::reverse_face_orientations(faces_to_reverse, mesh);
// there are still borders between previously incompatible faces: stitch to close the mesh // there are still borders between previously incompatible faces: stitch to close the mesh
PMP::stitch_borders(mesh); PMP::stitch_borders(mesh);
assert(CGAL::is_closed(mesh)); assert(CGAL::is_closed(mesh));
CGAL::IO::write_polygon_mesh("reoriented_and_stitched.off", mesh, CGAL::parameters::stream_precision(17)); CGAL::IO::write_polygon_mesh("oriented_and_stitched.off", mesh, CGAL::parameters::stream_precision(17));
return 0; return 0;
} }