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split long edges

This commit is contained in:
Sébastien Loriot 2025-02-11 08:38:04 +01:00
parent 692e0ef977
commit c7427fb729
2 changed files with 53 additions and 4 deletions
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4
Polygon_mesh_processing/examples/Polygon_mesh_processing/acvd_example.cpp
View File

@ -42,7 +42,7 @@ int main(int argc, char* argv[])
}
///// Uniform Isotropic ACVD
#if 1
#if 0
std::cout << "Uniform Isotropic ACVD ...." << std::endl;
auto acvd_mesh = PMP::acvd_isotropic_remeshing(smesh, nb_clusters);
CGAL::IO::write_polygon_mesh(stem+"_acvd_"+nbc+extension, acvd_mesh);
@ -51,7 +51,7 @@ int main(int argc, char* argv[])
#endif
//// With Post-Processing QEM Optimization
#if 1
#if 0
std::cout << "Uniform Isotropic ACVD with QEM optimization ...." << std::endl;
auto acvd_mesh_qem_pp = PMP::acvd_isotropic_remeshing(smesh, nb_clusters, CGAL::parameters::postprocessing_qem(true));

53
Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/acvd/acvd.h
View File

@ -345,6 +345,7 @@ std::pair<
typedef typename Eigen::Matrix<typename GT::FT, 4, 4> Matrix4x4;
typedef typename GetVertexPointMap<TriangleMesh, NamedParameters>::const_type Vertex_position_map;
typedef typename boost::graph_traits<TriangleMesh>::halfedge_descriptor Halfedge_descriptor;
typedef typename boost::graph_traits<TriangleMesh>::edge_descriptor Edge_descriptor;
typedef typename boost::graph_traits<TriangleMesh>::vertex_descriptor Vertex_descriptor;
typedef typename boost::graph_traits<TriangleMesh>::face_descriptor Face_descriptor;
typedef typename boost::property_map<TriangleMesh, CGAL::dynamic_vertex_property_t<int> >::type VertexClusterMap;
@ -382,19 +383,67 @@ std::pair<
CGAL_precondition(CGAL::is_triangle_mesh(pmesh));
const double clusters_to_vertices_threshold_ratio = choose_parameter(get_parameter(np, internal_np::clusters_to_vertices_threshold_ratio), 0.1);
// TODO also call split_long_edges: max edge length shall not be larger than 3 * input mean edge length
// TODO cheese crashes
// TODO compute less qem things if not used
// TODO use symmetric matrices?
// TODO: copy the mesh in order to not modify the original mesh
//TriangleMesh pmesh = pmesh_org;
int nb_vertices = num_vertices(pmesh);
int nb_vertices = vertices(pmesh).size();
// For remeshing, we might need to subdivide the mesh before clustering
// This should always hold: nb_clusters <= nb_vertices * clusters_to_vertices_threshold_ratio
// So do the following till the condition is met
// first split long edges (TODO: also for curvation based alternative?)
// TODO: do it all the time, even if we have enough vertices?
if (nb_clusters > nb_vertices * clusters_to_vertices_threshold_ratio)
{
std::vector<typename GT::FT> lengths;
lengths.reserve(num_edges(pmesh));
typename GT::FT cum=0;
int nbe=0;
for (Edge_descriptor e : edges(pmesh))
{
lengths.push_back(std::sqrt(squared_distance(get(vpm, source(e, pmesh)), get(vpm, target(e, pmesh)))));
cum += lengths.back();
++nbe;
}
typename GT::FT threshold = 3. * cum / nbe;
std::vector<std::pair<Edge_descriptor, double>> to_split;
int ei=-1;
for (Edge_descriptor e : edges(pmesh))
{
typename GT::FT l = lengths[++ei];
if (l >= threshold)
{
double nb_subsegments = std::ceil(l / threshold);
to_split.emplace_back(e, nb_subsegments);
}
}
for (auto [e, nb_subsegments] : to_split)
{
Halfedge_descriptor h = halfedge(e, pmesh);
typename GT::Point_3 s = get(vpm, source(h,pmesh));
typename GT::Point_3 t = get(vpm, target(h,pmesh));
for (double k=1; k<nb_subsegments; ++k)
{
// the new halfedge hnew pointing to the inserted vertex.
// The new halfedge is followed by the old halfedge, i.e., next(hnew,g) == h.
Halfedge_descriptor hnew = Euler::split_edge(h, pmesh);
if (!is_border(hnew, pmesh))
Euler::split_face(hnew, next(h, pmesh), pmesh);
if (!is_border(opposite(h, pmesh), pmesh))
Euler::split_face(opposite(h, pmesh), next(opposite(hnew, pmesh), pmesh), pmesh);
put(vpm, target(hnew, pmesh), barycenter(t, k/nb_subsegments, s));
}
}
nb_vertices = vertices(pmesh).size();
}
while (nb_clusters > nb_vertices * clusters_to_vertices_threshold_ratio)
{
typename GT::FT curr_factor = nb_clusters / (nb_vertices * clusters_to_vertices_threshold_ratio);